Category: Evolution

Abstract

The environmental conditions and the nature of seeds available have influenced the evolution and adaptation of finches beaks to their feeding habits. The goal of the study was to demonstrate how different beaks influence feeding habits of finches. In this view, the study hypothesized that the small beaks prefer picking small-sized seeds (millet) while large beaks prefer picking larger seeds (thistle). The experiment simulated four beaks, namely, normal pliers, curved pliers, large forceps, and small forceps, which were used in picking sunflowers, millet, and thistle seeds.

Phenotypic characteristics of beaks are important for they influence the feeding habits and determine the survival ability of finches. The key results that led to the rejection of the hypothesis that the small beaks prefer picking small-sized seeds (millet) while large beaks prefer picking larger seeds (thistle) indicated that small pliers and curved pliers prefer sunflower seeds while large forceps and small forceps prefer millet seeds. Thus, the conclusion is those small pliers and curved pliers can easily pick seeds with thin shells such as sunflower seeds while large forceps and small forceps can easily pick seeds with hard shells such as millet.

Introduction

Darwins theory of evolution posits that living things are constantly evolving in response to selection pressure. As the environment changes, the native species adapt to their habitat conditions by evolving new inheritable physical/behavioral traits (Podos and Nowicki 506). The evolution of finches illuminates the changes in recent earths biodiversity and enhances understanding of the role of genetic diversity. Darwin finches comprise of over 13 passerine bird species native to the Galapagos Islands, South America (Grant and Grant 135). Darwins finches show remarkable evolutionary changes that allow them to occupy different niches in similar habitats. The finches evolved distinct beak types to adapt to different diets in response to selection pressure. The beak type determines each birds access to a particular food source available in its natural habitat, such as the Galapagos Islands. Podos and Nowicki note that the evolution of different beak sizes/types ensured that up to 15 different species of finches could coexist in the islands (507). While some evolved long, slender beaks suitable for eating insects, others developed shorter, thicker beaks for feeding on seeds of different sizes.

The theory of natural selection dictates that organisms must adapt to their habitats to survive (Grant and Grant 135). It produces heritable biological variations that could be favorable, deleterious, or neutral. The accumulation of advantageous traits makes a species fit to compete and survive in changing habitats. The underlying assumptions of this theory include a natural variation that produces desirable, unfavorable, or neutral traits, inheritance, and survival for the fittest (Podos and Nowicki 509). Therefore, Darwins finches evolved different beaks to feed on different food sources as an adaptive strategy.

For this experiment, the aim was to demonstrate how different beak types/sizes, represented by normal pliers, curved pliers, large forceps, and small forceps, determine each birds access to seeds of variable sizes. We hypothesized that the small pliers would pick small-sized seeds (millet) more quickly than tongs, which would be suited for picking larger seeds (thistle). The underlying rationale is that each beak size (tool) is suited for picking a particular seed size, which would explain the variation in total seed collections at the end of the experiment. The experiment helped mimic how selection pressure drives evolutionary changes in organisms.

Methods

In the experiment, we simulated natural selection in finches, where the beak type determined the ability to compete for different forms of food sources, such as sunflower, millet, and thistle. The experiment involved four types of beaks represented by normal pliers, curved pliers, large forceps/tongs, and small forceps. The simulation involved using the beaks to pick or eat different types of seeds, which included sunflower, millet, and thistle.

Seven groups of participants simulated different beaks to mimic beak adaptations in the Darwin finches. Each participant was required to use different beaks in picking different types of seeds throughout the experiment. The seeds (100 from each type) were counted and mixed on a desk. Using the assigned beak in each round, each participant ate as many seeds of a particular type as possible within one minute. The seeds eaten were placed in a collection cup for each trial. Each individual experiment was repeated four times (trials) for each condition. The experiment involved two treatment arms, that is, normal and drought conditions. An average of the seeds collected in each cup represented the number of seeds eaten by individual beaks within one minute. Experiment data were collected, recorded, and combined with other trials to be analyzed using Excel.

Results

The results of the experiment comprise an average number of seeds picked by each type of beak in different conditions. The results showed that the number of seeds picked by finches varied according to the type of beaks and the environmental conditions. The data in Figure 1 shows that under normal environmental conditions, small pliers picked an average of 10.25 sunflower seeds, 2.85 millet seeds, and 1.28 thistle seeds. Under the same environmental conditions, curved pliers picked an average of 9.39 sunflower seeds, 4.21 millet seeds, and 1.14 thistle seeds. The average numbers of sunflower seeds picked by large forceps and small forceps were 1 and 0.642 respectively. Additionally, the average numbers of millet seeds picked by large forceps and small forceps were 14.1 and 7.75 whereas those of thistle seeds were 10.64 and 4.35 respectively.

Figure 1 shows that small pliers and curved pliers preferred sunflower seeds followed by millet seeds whereas thistle seeds had the least preference during the normal conditions. Moreover, during the normal conditions, large forceps and small forceps preferred millet seeds followed by thistle seeds while sunflower seeds had the least preference.

Comparatively, it is apparent that the average numbers of seeds picked by different beaks during drought conditions (Figure 2) follow the same trend as during normal conditions. The average numbers of seeds picked by small pliers are 18.6, 1.03, and 0.5 whereas those of curved picks are 17.64, 2.67, and 0.5 for sunflower, millet, and thistle respectively. The average numbers of seeds picked by large forceps are 2.365, 10.21, and 3.6 while those picked by small forceps are 1.75, 10.28, and 4.25 for sunflower, millet, and thistle correspondingly. Figure 2 also depicts that small pliers and curved pliers prefer sunflower seeds whereas large forceps and small forceps prefer millet seeds during the drought conditions.

Discussion

As the goal of the study was to demonstrate how different beaks influence feeding habits of finches, the results provide invaluable information about the adaptation of finches beaks. The results reveal that the average number of seeds picked varied according to the type of seed, type of beak, and the environmental condition. The apparent trend is that during both the normal and drought conditions, beaks had similar preferences of seeds. For instance, during the normal conditions and the drought conditions, small pliers and curved pliers preferred sunflower seeds while large forceps and small forceps preferred millet seeds.

Overall, millet seeds are seeds picked with the highest frequency during the normal conditions while sunflower seeds are seeds with the highest frequency during the drought conditions. However, the frequency was not consistent for all types of beaks because the frequency of sunflower seeds was the highest among small pliers and curved pliers while the frequency of millet was the highest among large forceps and small forceps during both the normal and the drought conditions.

The most adaptive beak is small forceps because it prefers both millet and thistle seeds and the environmental conditions do not significantly influence the frequency of its preferred seeds. According to Grant and Grant, finches acquire adaptive features that allow them to feed on different seeds depending on the environmental conditions (133). A comparison of the seeds eaten at the highest frequency during different environmental conditions indicates that the highest frequency increased during the drought conditions. The reason for the increase in the highest frequency is that drought conditions allow finches to utilize their adaptive abilities to crack preferred seeds (Podos and Nowicki 501). The experience of drought led to the selection of small pliers, curved pliers, and small forceps for adaptation because of the increased frequency of seeds picked whereas large forceps were selected against adaptation due to the decreased frequency of seeds picked.

The collected do not support the hypothesis that the small pliers would pick small-sized seeds (millet) more quickly than tongs, which would be suited for picking larger seeds (thistle). The results indicate that small pliers and curved pliers easily pick sunflower seeds while large forceps and small forceps easily pick millet seeds. In conclusion, the results show that small pliers and curved pliers can easily pick seeds with thin shells such as sunflower seeds while large forceps and small forceps can easily pick seeds with hard shells such as millet.

Works Cited

Grant, Peter and Rosemary Grant. Adaptive Radiation of Darwins Finches.American Scientist, vol. 90, no. 2, 2002, pp. 130-139.

Podos, Jeffrey and Stephen Nowicki. Beaks, Adaptation, and Vocal Evolution in Darwins Finches. Bioscience, vol. 54, no. 6, 2004, pp. 501-511.

Introduction

Placental mammal is another name used to refer to primates. They include humans, apes and monkeys. Their different adaptive strategies have enabled them to survive in different environmental conditions. Availability of various foods in the forest forced them to become omnivorous. There are different factors to consider when learning about evolutionary trends of primates. These factors include diet and dentition, Crania and Limbs. This paper analyzes the evolutionary context of prosimians, anthropoid monkeys and hominoid apes. In addition, it will address the main cause of extinction among Miocene apes.

Prosimians

Prosimians are found in the order Primates together with anthropoids. Research indicates that, these primates evolved earlier than anthropoids. This is the reason why archeologists referred to them as lower primates in the 19^th Century. Lorises and Lemurs are outstanding examples of prosimians. They were mainly found in tropical regions like North America. This has changed over time; records indicate that, Old World provides an ideal environment for these species. Lemurs mainly inhabit Madagascar Island. These species had a bushy tail that provided them with stability when moving from one tree to another. There herbivores nature enabled them to consume leaves, fruits and roots available in the jungle. Research has it that these species are more social than lorises (Simons, 2009).

Cheirogaleidae is one among the families of Lemurs. The size of full-grown species can be compared to that of a mouse. Fruits, baby birds and insects, make up the diet of these species. There sharp sense of hearing plays a vital role in hunting at night. Avahis, Sifakas and Indris, are in the Indriidae family. These species are bigger than other species from other families. These species use piercing vocalizations in order to guard their territories. Their long legs help them in moving from one tree to another. It is due to the nature of their legs that these species cannot be able to walk but hop. Daubentoniidae is the last family of lemurs. These species are not common because they reside mostly on trees. Their teeth and hands are unique compared to other primates. Their long incisor teeth and elongated fingers help them to obtain food from tree barks and coconut meat (Simons, 2009).

Anthropoid monkeys

Suborder Anthropoidea consists of one hundred and forty five species. Monkeys make up 90% of these species. Ten percent is mainly humans and apes. These species are more developed, intelligent and larger than Prosimians. The origin of these primates is not clear. There are different individuals who have tried to explain the origin of these primates by providing evolutionary rootstocks, places and time. Some researchers argue that anthropoid monkeys mainly evolved from prosimian primates. It is not easy to understand the evolution of anthropoids without focusing on their origin. Most individuals argue that Africa is the cradle land for these primates. Some archeologists strongly opposed this argument claiming that anthropoids did not have anything to do with Africa. They held that Asia is the cradle land for anthropoids (Trevathan, Kilgore, & Jurmain, 2011).

Catarrhine and Platyrrhine are an example of anthropoids infra orders. Platyrrhine has a nose that is flat with a broad septum while Catarrhines nose has a narrow septum. Catarrhines nose can be compared to that of man. Anthropoid monkeys have mammalian teeth that used for eating different types of foods. They include incisors, canines, premolars and molars. Incisors play a crucial role of nipping food. Canines do tearing and piercing of food. The multiple cusps of molars and premolars enable them to grind food. 2.1.3.2 is the dental formula of primates. Catarrhines have a different dental formula from other primates. Their dental formula is 2.1.2.3 (Trevathan, Kilgore, & Jurmain, 2011).

Old World anthropoid monkeys have the same dental formula like that of Catarrhine. Old World monkeys are bigger than New World monkeys. In addition, they are semi-terrestrial while New World Monkeys are arboreal.Prehensile helps New World monkeys to hold on branches. Ischial callosities enable Old World Monkeys sit and sleep for long periods. In addition, these pads enable them to sit on surfaces like rocks and branches. Some Old World monkey females have swellings on their genitalia (Simons, 2009).These swellings occur due to hormonal changes in their bodies. These changes are essential for ovulation preparation. These swellings also play a crucial role in attracting male species through odors they produce.

Hominoid apes

Research indicates that different geographic and environmental factors played a vital role in the development of hominoid apes. These species evolved from Africa and later moved to Eurasia. Hominoids are evident in different countries like, India, Hungary, Turkey, Pakistan, Western Europe and China. In order to understand these species, archeologists have divided their evolution into different forms. They include African form, European form and Asian forms (Jablonski & German, 2004).

This primate had a larger brain capacity than other primates. Its ability to adapt to changes in the environment enabled it to survive in Eurasia. Some apes specialized in taking fruits and leaves while others specialized in consuming small birds. The bipedal posture of these apes enabled them to climb on trees easily. Another similarity is evident from the nature of his hand. He had hands that could enable him grasp food and tools (Jablonski & German, 2004).

Extinction of most species of Miocene apes

Some people tend to think that evolution for apes has seized while that of humans is in progress. The truth is that, evolution for apes is the same as that of humans. Fossil record indicates that, the evolution for Miocene apes is poor just like that of humans. Eurasian climate was initially ideal for the survival of these primates. The forest temperatures were extremely warm. In addition, adequate rainfall enabled enough supply of fruits and leaves that served as the main source of food for these primates (Trevathan, Kilgore, & Jurmain, 2011).

It is clear that Miocene apes are becoming extinct. Nature has been blamed to the causes of this extinction. Some individuals argue that, the major contributors towards the extinction of Miocene apes are human activities. Climatic change and rainfall reduction have led to fragmentation of forests. Forests are the main source of food for Miocene apes. This means that, lack of forests forces these species to starve to death. Habitat destruction carried out by man causes this extinction. Farmers clear forests in order to attain land they can use for practicing agriculture. Man also clears bushes in order to attain charcoal and wood for cooking. Man has also been accused of capturing these animals as pets (Simons, 2009).

Conclusion

Primates can also be termed as placental mammals. Primates are made of different groups of species. Each group had unique features and behaviors that enabled it to adapt and survive in its environment. These groups include prosimians, anthropoid monkeys and hominoid apes. The evolution of these primates took place differently. The period at which prosimians evolved called Paleocene. Anthropoid monkeys evolved during the Eocene age while hominoids evolved during the epoch age. These primates mainly attained their foods from trees. They fed on insect, birds, insects and roots. Research indicates that human activities have significantly contributed towards the extinction of Miocene apes.

References

Jablonski, N. G., & German, R. Z. (2004). Shaping Primate Evolution: Form, Function, and Behavior. Cambridge University Press: Cambridge. Print.

Simons, E. L. (2009). Primate evolution: an introduction to mans place in nature. Michigan: University of Michigan. Print.

Trevathan, W., Kilgore, L., & Jurmain, R. (2011). Introduction to Physical Anthropology 2010-2012. New York: Cengage Learning. Print.

The Authors Main Argument

In his article, Flannery (1972) presented the discussion of how ancient societies developed in the context of analyzing two opposite views associated with ecologists and humanists approaches. The authors main argument is that humanists views regarding the ecological approach are not appropriate, and these researchers should also refer to ecologists ideas, as well as ecologists should accept the importance of culture because the ecosystem approach covers both natural and cultural phenomena in societies development. Thus, in his article, the author promotes the idea that a multivariate model of developing the state in the context of ecological views is most appropriate.

The Development of the Main Argument

It is important to note that Flannery (1972) started the development of his key idea by emphasizing the debates around the topic of complex societies progress. Thus, he provided the background for his argument while stating that researchers usually view the ecological approach as inappropriate and inadequate for analyzing the variety of complex societies. As a result, this method of developing the discussion allowed the author to present his argument as a response to the existing debates.

Flannery (1972) also defined the key concept of civilization that he actively applied in his study. This approach helped the author to build a conceptual framework for his analysis. As a result, it is possible to state that the introductory part of the article was effectively used by the author to present his key idea and then concentrate on its development and support with the help of evidence.

Following the key stages of developing his thought, Flannery (1972) continued his discussion by describing types of societies from the simplest ones to complex states. Thus, the author focused on describing egalitarian societies concerning the specifics of bands and tribes in the context of the ecological approach. Then, the researcher provided a detailed discussion of chiefdoms and the problem of hereditary inequality concerning various cultural theories.

The next step was the discussion of complex forms of societies, including stratified societies or states. At this stage, it was important to accentuate prime movers that are traditionally viewed by researchers as triggers for the development of states. However, Flannery (1972) criticized these movers while supporting his key argument and stating that the actual process of developing a higher society is complicated, and it involves both ecological and cultural aspects. As a result, he introduced the idea of multivariant causality.

After analyzing the evolution of societies from the simplest forms to more complex variants, Flannery (1972) referred to the idea of multivariant causality as the model for developing the state that can include both ecological and cultural components. The author developed the idea while discussing such important processes as segregation and centralization among other ones because they can potentially influence the progress of states.

Furthermore, Flannery (1972) developed his idea of the evolution of societies while providing evidence to state that the simplest forms of societies develop into higher forms not only because of ecological processes but also because of cultural ones that are based on sharing information. Thus, it is possible to note that the theorist paid much attention to accentuating the multivariate character of his model as his specific vision of the evolutionary theory. This step helped the author to improve his theoretical discussion and add more details.

Also, in the final parts of his work, Flannery (1972) focused on discussing two important socio-environmental processes in the context of the evolutionary theory, which can influence the development of societies, which are promotion and linearisation. The key principles of these processes were also presented in figures and tables to accentuate their role in the evolution of numerous different societies.

Finally, when summarising the results of his study and providing the key assumptions of his theory, Flannery (1972) formulated a list of rules that are important to understand how civilizations can develop in the context of the evolutionary theory and the authors unique multivariate model. From this point, referring to his main argument, the author accentuated the role of ecological or environmental processes and cultural factors in the development of societies. The article presented the development of ideas from basic ones to the complex model.

The Opinion Regarding the Argument

Analyzing Flannerys (1972) argument and concluding regarding its persuasiveness, it is possible to state that the authors model and its discussion are effective and supported by other researchers in the field. From this point, it is necessary to refer to Diamonds (2017) ideas that seem to be based on Flannerys (1972) views. Thus, the author of the discussed article is convincing because his key ideas are reflected in other works on the problem of states evolution.

In his work, Diamond (2017) promotes the idea that environmental differences between societies are key factors to influence their development in terms of culture and the progress of technology. Certain ecological factors contributed to the progress of some states in terms of their culture. As a result, it is almost impossible to regard environmental factors without referring to cultural aspects.

Thus, some societies are predisposed to the cultural progress in comparison to other societies. Still, it is impossible to refer only to environmental situations or cultural achievements to analyze the outcomes of evolution. The ideas of Flannery (1972) regarding the importance of multivariant causality seem to influence Diamonds (2017) influential conclusions about the development of some societies in contrast to others.

Conclusion

While concluding on the presentation of Flannerys argument in his article, it is critical to note that the researcher succeeded in logically developing his ideas. He used an effective approach to providing his view as a response to the debates, and he also offered a step-by-step development of his argument into a strong theoretical model that is supported by figures and evidence. Additionally, even though the discussed multivariate model was introduced by the author in the 1970s, it is still reflected in other theorists works.

This fact allows for speaking about the appropriateness of this evolutionary model because it includes several important factors that seem to contradict each other (ecological and cultural ones), and that is why they need to be addressed as a complex. The author of the article chose to discuss the causation in the question of developing societies from a unique perspective that was not previously applied by other researchers in the field. It became possible to achieve success and present a detailed theoretical model that can reflect different perspectives in the most efficient manner. Despite some controversial aspects, the flow of thoughts presented in the article is rather logical and convincing.

References

Diamond, J. (2017). Guns, germs, and steel: The fates of human societies (20th ed.). New York, NY: W. W. Norton & Company.

Flannery, K. V. (1972). The cultural evolution of civilizations. Annual Review of Ecology and Systematics, 3(1), 399-426.

Evolution refers to the biological changes that occur among individual members of population over time. The changes are usually due to biological conditions and environmental factors. However, it is important to note that the entire population undergoes evolution and not just the individuals in such a population. There are four known forces of evolution and they include natural selection, gene flow, genetic drift, and mutations.

Natural selection involves differential survival traits. Different individuals in a given population will adapt to different characteristics. Consequently, they are able to compete with other species for scarce resources. Due to intense competition, species that are able to adapt to these characteristics survive while the rest become extinct. Many scientists refer to this phenomenon as survival for the fittest.

This is a situation in which individuals who lack the ability to adapt to the needed characteristics are wiped out. At the same time, the traits of a given generation can change from one generation to another. Natural selection affects variations in a population through changes that occur to the phenotypes of different organisms. What this appears to suggest is that natural selection calls for behavioral and structural changes of body parts.

On the other hand, gene flow is a term used in reference to the movement or migration of genetic materials across different populations. The flow of genes within a population increases variations of individuals within that population. Gene flow occurs mainly due to the highly mobile organisms in a population.

Mobile organisms are able to interact with other organism and as a result, the exchange of genetic material from one organism to another takes place. This is what usually happens during mating. The resulting generations will thus posses the dominant genes from the two parents. In most cases, the resulting generations possess the hybrid genes of the parent genes.

In genetic drift, some individuals may leave behind a higher percentage of genes than others. Consequently, some genes may end up drifting away as new generations are produced. The genes that drift away are usually lost forever. That is why certain organisms become extinct.

Thus, genetic drift reduces the chances of genetic variations from one generation to another. Mutation is the change that occurs to the DNA material of organisms. Mutations can be harmful or beneficial. Mutations that contribute a lot to evolution are those that occur in the sex cells, as opposed to the somatic cells. This is because it is only the changes that occur in the reproductive cells that can be passed from the parent to an offspring.

Mutations can lead to changes in the phenotype of organisms. A single mutation can bring about unnoticeable or small change in an organism. It can also result in a big change in another type of organism. Sometimes, mutations do not cause any changes to organisms. Thus, mutations produce noticeable changes only when the genes involved are similar.

An isolation mechanism is any factor that prevents groups of organisms from interbreeding. Isolating mechanisms can be behavioral or biological. For example, different seasons of mating for different organisms may hinder two different groups of organisms from interbreeding. Again, sterile organisms from a certain group are not able to interbreed. Consequently, similar organisms end up interbreeding. This enhances speciation, in which similar off springs are produced.

Introduction

Paleontology is a wide field of study that is filled with a long and fascinating past and an even more intriguing and hopeful future (UCMP, n.d, p.1). A large number of people think that this field involves just the study of fossils but it is much more than this. According to UCMP (n.d), paleontology is defined as the study of what fossils tell us about the ecologies of the past, about evolution, and about our place in the world (UCMP, n.d, p.1).

This field of study takes in knowledge from other fields such as anthropology, biology, and computer science as well among others, in order to have the understanding of the processes which have contributed to the coming about and ultimate destruction of the various kinds of living organisms, beginning from the time life started.

The field of paleontology is traditionally broken down into a number of sub-disciplines and these include; palynology, vertebrate paleontology, invertebrate paleontology, micropaleontology, paleobotany, human paleontology, paleocology, taphonomy, and ichnology (UCMP, n.d, p.1).

In this paper, the discipline of paleontology is going to be explored and the main concern will be on looking at paleontology and how it relates to the Darwins evolutionary theory. In the discussion, the background information on the fossil record is going to be given and this will be followed by the main discussion on paleontology and the evolutionary theory. The conclusion section will give a summary of the discussion.

Fossil Record

Before embarking on the main discussion, we need to consider what the fossil record is because the discussion is going to be based on this to some extent. The fossil record is defined as the collective accumulation of artefacts which have been fossilized all over the world (Fossil record, 2003, p.1).

When looked at as a whole, there can be offering of very interesting information by the fossil record concerning how life evolved on earth. The scientists can make a decision to engage in studying the fossil record in its entirety or may chose to go to a specific period, in an effort to get information about the earths history and the living organisms that dwelt on it (Fossil record, 2003).

A large number of fossils, amounting to millions, which are found in rocks, exhibit forms of evolution through time and also exhibit a large number of transitions that take place in species. In the year 1831, Charles Darwin commenced on assembling a huge bulk of evidence and in turn engaged in assessing and analysing it for over one and a half decades before keenly deducing a fresh rule of descent of organisms with no modification (Calabro, 2000, p.1).

The fossil record is clear on the evolution of life beginning from simple forms of life to complex forms ones. The fossil record has been seen as having been very important in the development of the evolutionary theory by Darwin. However, it was pointed out that the fossil record was incomplete and Darwin criticized it for the weaknesses associated with it (Calabro, 2000).

Paleontology and the Evolutionary Theory

According to Sepkoski (2008), there exists a direct relationship between the health of a scientific discipline and the quality of its data sources. The discipline of paleontology has a rich source of data in the fossil record(Sepkoski, 2008, p.27).

However, there has been contradictions in opinions in the course of time in regard to the completeness of the fossil record and the sufficiency it has for making conclusions on the evolutionary trends and patterns (Sepkoski, 2008). In the more recent times, experts in the field of paleontology have had enthusiasm about the fossil record quality and there has been optimism about its approximations and the completeness it has (Benton, 2003; Jablonski et al., 2003, Foote & Sepkoski, 1999).

However, In the course of the last one century or even more, after Darwins Origin of Species publication, there was strict hindering of the capability of paleontologists to take part fully in the discussions concerning the evolutionary theory by perceptions that, the fossil record was not a complete or reliable source of data (Sepkoski, 2008, p.27).

While paleontology developed its professional distinctiveness in the course of the 1900s, the critical task for the experts in this field was to set up the sufficiency of the data they had to give answers to questions raised about the authenticity of the contributions made by paleontology to the evolutionary theory.

This program involved carrying out determination of the appropriate connection between paleontology and the biology and geology fields, which are its very intimately related sister disciplines. It is pointed out that, in the absence of this backing on behalf of its data, paleontology might never have claimed a place at the high table of evolutionary biology, and the modern discipline of paleobiology might never have existed (Sepkoski, 2008, p.27).

During the start of the 1800s, at a time paleontology methodology and discipline orientation were coming up, the current fields of science as we now know them were not there. In the year 1859, such a term as biology was at that time still a relatively new innovation and even Charles Darwin himself did not utilize it in any of his editions of Origin of Species (Sepkoski, 2008, p.27). At that time, the term paleontology was in general use.

One of the scientists, Charles Lyell, during that period gave a definition of this term as the science which treats fossil remains; both animal and vegetable &.but it would have been quite unusual for a scientist to identify solely as paleontologist or even a geologist (Sepkoski, 2008, p.28). Hence, the paleontology professional position, especially when compared with the biology field, is a debatable issue in the course of the time those fields had turned out to be generally recognized as independent fields.

However, it is pointed out that the geological as well as paleontological evidence were of great significance to Charles Darwin in setting up the evolutionary theory (Sepkoski, 2008).

This was mainly for the reason that the fossil record historical evidence made it possible for him to present arguments for chronological evolutionary succession. In the initial edition of the Origin and those that followed, Darwin engaged in the extensive discussions about the importance of fossil succession, and it is not to overstate by pointing out that paleontology was a backbone of the argument he presented for evolution.

However, it is pointed out that Charles Darwins conservative evaluation of the fossil record completeness hindered the capacity of the paleontologists that came thereafter to totally engage in joining in the development of the evolutionary biology community (Sepkoski, 2008,). Among the greatest fears was the idea that the incompleteness of the fossil record would be used to criticize his theory (Sepkoski, 2008, p.28).

The dilemma that Darwin faced, then, was that he was concurrently needed and faced embarrassment caused by the paleontological evidence found in the fossil record. As on one hand Darwin almost surely had no intentions of diminishing the status of paleontology, on the other hand, the diagnosis he undertook of the limitations which the fossil record had, had precisely that effect for almost a century after the Origin publication.

Darwin wrote about the weaknesses in the fossil record. Whilst he presented the case that the fossil data were essential for a clear understanding of the organic history, he pointed out that the absence of transitional forms between species is an inherent and insoluble problem for paleontologists and geologists (Sepkoski, 2008, p.28).

However, it is pointed out that the theory presented by Darwin of evolution brought in a revolution in paleontology for the reason that the fossil record turned out to be the only possible source of evidence that evolution had actually taken place. In the absence of evolution, paleontology just made interesting, descriptive observations about the form and distribution of once living creatures; without paleontology, there is no concrete evidence that evolution happened (Sepkoski, 2008, p.29).

But paleontology, on its own, could not independently contribute towards the theory of evolution because this theory relied on evidence which came from such fields as geology, biology and heredity among other fields in order to bring meaning to the paleontological data (Sepkoski, 2008).

This means that, in the absence of the theory of evolution to paleontology, this field of study (paleontology) could not find a solution to issues concerning the organic nature history; it called for the Darwins theory of evolution to carry out the contextualization of the contributions it had made while excusing its shortcomings.

Darwin had relatively pointed out that paleontology had already offered all it was possibly to give to having understanding of evolution. Therefore, for those who supported Darwin, there existed no immense necessity to examine the fossil record. In actual fact, those who supported Darwin were much more likely to have a wish to engage in pushing paleontology into the background (Sepkoski, 2008, p.29).

For instance, Colman (1971) presents an argument that to the biologist that fossil record posed more problems than it resolved&the incompleteness of the recovered fossil record, in which a relatively full historical record for any major group was still lacking, was the very curse of transmutationist (p.66).

Hunt (2010), also citing the weakness in the fossil record as diagnosed by Darwin, points out that; in responding to the lack of absence of species-levels transformation within the fossil records, Darwin presented an argument that that the fossil record was too incomplete, too biased, and too poorly known to provide strong evidence against his theory (Hunt, 2010, p.61). Hunt (2010), in his research, carried out the evaluation of this view of the fossil record in light of a period of one and a half century of the paleontological research that followed.

He points out that even if the assessment carried out by Darwin of the completeness and resolution of fossiliferous rocks was in several ways astute Hunt (2010, p.61), in the current day, there is much better exploration of the fossil record and there is also better documentation and understanding of this record than the way it was way back in the year 1859 (Hunt, 2010).

More specifically, a logical big set of studies which seek to trace evolutionary trajectories within species can now be brought to bear on Darwins expectation of gradual change driven by natural selection(Hunt, 2010, p.61).

Conclusion

As it has been looked at in the discussion above, it can be concluded that, paleontology is a very wide discipline and has been there for a long time. This discipline has played a very important role in the evolutionary theory, which was set up by Charles Darwin. The fossil record enabled Charles Darwin to develop this theory.

But over time, different views have come up concerning the completeness of the fossil record and its satisfactoriness for drawing conclusions on the evolutionary trends and patterns. For instance, Darwins conservative assessment of the completeness of the fossil record hindered the capability of the successive paleontologists to entirely engage in joining in the development of the evolutionary biology community.

However, it is important to note that Darwins evolutionary theory caused a revolution in the field of paleontology and this was because the fossil record turned out to be the only available source of evidence that indicated that evolution had actually occurred.

Yet paleontology, standing alone as an independent field, could not contribute to the theory of evolution and this is for the reason that this theory relied on evidence that was obtained from other fields which include the biology, geology and heredity fields or disciplines among others in order to make the paleontological data to turn out to be of significance.

References

Benton, M. J. (2003). The quality of the fossil record. London, England: Taylor & Francis.

Calabro, T. (2000). The fossil record and evolution. Web.

Coleman, W. (1971). Biology in the Nineteenth Century: Problems of Form, Function, and Transformation. New York, NY: Wiley.

Foote, M. & J. Sepkoski, J. (1999). Absolute measures of the completeness of the fossil record. Nature, 398(6726), 415-417

Fossil record (2003). Web.

Hunt, G. (2010). Evolution in fossil lineages: Paleontology and the origin of species. The American Naturalist, 176 (1), 61  76.

Jablonski, D. R. Kaustuv, J. W. Valentine, R. M. Price, & Anderson, P.S. (2003). The impact of the pull of the recent on the history of marine diversity. Science, 300(5622),1133-1135.

Sepkoski, D. (2008). Evolutionary paleontology and the fossil record: A historical introduction. Wilmington, NC: University of North Carolina Press.

UCMP. (n.d). What is paleontology?. Web.

Introduction

Evolution is the process of gradual change of plants and animals from their primitive nature to the current state. This process takes a long period and many theories and research support the evolution of various plants and animals as well the universe. This paper focuses on the evolution of animals and in precise the evolution of the vertebrates. The vertebrates and other animals passed through relative diversity groups through time. This paper seeks to research and clearly explain to someone without biology knowledge why the groups to which humans belong are not the last point of vertebrate evolution using the node of the phylogeny tree.

Why the group to which humans belong is not the last point in the evolution of vertebrates?

Human beings evolved from primitives over years. These primitives had larger brains in proportion to their body size than all terrestrial mammals (Benton, 2005). He further asserts that the primitives had mammalian characteristics although at improved levels. The primitives had eyes that were large and close together on the front face and a reduced snout. The flattened face of most primates allowed them to look forward and have a large amount of overlap between the fields of the vision of both eyes, which makes stereoscopic, or three-dimensional, sight possible (Benton, 2005). This is possible to prove that primitives gradually evolved from mammals. The primates parental care for their offspring had significantly improved. Moreover, the borne that encloses the middle ear and other structures in the primitives was close to that of mammals though large (Barton and Briggs, 2007). Moreover, these primitives were believed to have evolved from mammalian fossils. In addition, there is a clear table of the evolutions and the period of the years that the evolution took place. It shows that the mammals were are not the highest evolution of the vertebrates but some more animals and primitives evolved until the modern man.

This knowledge made it easy to deal with the explanation of the thesis. Using the phylogeny or evolutionary tree of vertebrates, one might conclude that the mammals were the highest point of evolution. However, according to the research and studies are done, mammals are not. A phylogeny tree of vertebrates is a diagram that illustrates the evolution of vertebrates with time (Barton and Briggs, 2007). The phylogeny is like reading a family tree where, if we allow the root, which is the beginning of the tree to be a representation of the ancestral lineage, and the tips to be the branches to represent the descendants of that ancestor, then understanding the tree is easier. The ancestors here represent the fossils from which the vertebrates evolved. The Claude groups such as the reptilian, amphibian, and the other species represent the descendants of the fossils (Carroll, 1997). This can be compared to a family setup where the ancestors give rise to the first descendants who then give rise to the second descendants. The second descendants then give birth to the third that gives birth to the fourth, the fourth to the firth, and the family tree grows along with time. Initially, the evolution of the vertebrates started with a single node that rose to other branches. These branches then broke to give rise to more branches until the mammals evolved.

However, most people, as well as researchers, perceive mammals to be the highest point of evolution of vertebrates. This is not the case as the descendants of the ancestor in our family were set up in the example above; the mammals gave rise to the primitives that had more developed features than the mammals. Similarly, these primitives have evolved over the past years to what we call the modern man (human beings) (Carroll, 1997). Therefore, having this in mind it is possible to transform the same knowledge and judgment to the thesis of our topic that human beings are not the highest point in the evolution of the vertebrates. Human beings are a descendant of the many descendants of the ancestors of the fossils from which vertebrates evolved. This means that the human beings will then give or have given rise to other descendants not yet noted. As the ancestral lineages end after all the descendants are dead, the end of evolution ends after all the evolved and evolving species die. Thus, human beings still being in existence means that they are not the last in evolution.

Conclusion

When we consider the modern world and the ancient world, human beings have been living and existing in both worlds. The levels of technologies in the two worlds, that is, the modern and the ancient are far much apart and they advanced with time. For instance, the technologies applied in the 21st century are not the same as the technologies used in the 20th century. 21st-century technology is far much above 20th-century technology. This is a clear illustration that there has been a tremendous change in creativity and innovation, which is a result of critical thinking. This can, therefore, be evidence that there have been gradual changes in the thinking ability of human beings, which is part of evolution. Therefore, the hypothesis concludes that human beings are not at the highest level of vertebrates evolution. The challenge is what will be the next level of evolution.

Bibliography

Barton, Nicholas, and Briggs Derek. Evolution. New York: Cold Spring Harbor Laboratory Press, 2007.

Benton, Michael. Vertebrate Paleontology. Malden: Blackwell Publishing Company, 2005.

Carroll, Robert. Patterns and Process of Vertebrate Evolution. Cambridge: The Press Syndicate of the University of Cambridge, 1997.

Biogeography deals with the geographical distribution of organisms, species, and ecosystems across geological time. This segment of the study reveals variation in biological communities of organisms in the lines of geographical gradients of elevation, habitat area, isolation, and latitude. Familiarity with the spatial differences in the types and numbers of living organisms is of utmost importance in todays study of history and geography just as much as it was necessary for our ancestors. This is made manifest as we conform to the heterogeneous environments which in most cases are geographically predictable.

The systemic distribution of species of living organisms over several geographical areas is usually accounted for and explained by integrating and combining different historical factors including extinction, glaciations, extinction, and continental drifts as well as some deviations and variations in sea level, river capture, river routes and habitat (Browne, 36). This is in conjunction with a combination of supplies from ecosystem energies, isolation, geographical constraints, and landmass. On the same note, the theory of evolution stipulates that all the millions of species of living organisms on the face of the earth underwent an evolution process from a common ancestor through a process termed natural selection.

This idea sounded out that the organisms that got immeasurably adapted to their natural habitat managed to pass on their traits to their offspring and as time passed over such traits accumulated in a way that transformed those organisms to be what is currently termed as species. Evolution also sheds light on the formation of the earth about 4.6 billion years. Therefore, this article presents a detailed description of how biogeography supports the theory of evolution.

Objectives

This article aims at discussing how biogeography supports the theory of evolution. To fulfill this objective, this article would be intended;

• To show how biogeography defines the history of species that evolved
• To indicate how ecological biogeography supports evolution
• To use the study of biogeography to justify plate tectonic theory
• To explain how Island biogeography of species depicts the theory of evolution
• To describe Continental discontinuity of species about evolution
• To distinguish how evolution theory affirms the biogeography of distribution of islands
• To highlight how Darwins discovery was fostered by biogeography

How biogeography defines the history of species that evolved

Amazingly, from the definition of the duo fields of studies, it is crystal clear that one can not form lines of distinctions between biogeography and evolution. However, one thing that strikes me is that without the theory of evolution, biogeography has no basis. In other words, biogeography explains and affirms the theory of evolution in a greater dimension.

First, biogeography discusses the geographical distribution of species and how those living organisms interact with the environment while the theory of evolution analyses the origin of those species and their traits that make them behave or respond to different environmental conditions. It is also important to note that the theory of evolution underlies the core reasons for variations in environmental conditions on the surface of the earth such as on oceans, lakes, winds, seas, hills, mountains, snows, ice among others.

Therefore, to begin with, biogeography defines the history of species in their evolution process along with time scales. This is made possible by the use of evidence from other disciplines of history, especially archaeology. In this case, the fossils extracted from the earth from different places are rich in information that are necessary for the determination of the distribution of living organisms across the surface of the earth as well as the past interactions of various species.

In the bid to understand the sediments and relays facts from the fossils, biogeographers normally employ molecular biology. In the bid to come to terms with the evolutionary history of species with help of molecular biology, biogeographers normally use a tool referred to as area cladogram. Cladogram uses a taxonomic tree to show similarities between different species. The names of the species in the diagram are also replaced with geographical locations where different species are found. This enables these scientists to be in a position of determining environmental influence on the history of the evolution of various species of the same origin. The cladogram is as shown below;

Ecological biogeography and evolution

Ecology is another aspect of biogeography that affirms the theory of evolution. In this case, the current information that is gotten from the population is used explaining how those species might have evolved. This information depicts the behaviour of organism at different locations. In many instances, island communities for the basis of study in formation of hypothesis about development of species. Unlike other bigeographers who use cladogram, in this segment of study, richness equilibrium model is used. It presents uninhabited island that is characterized to be surrounded by other habitats that are not inhabited by other species of living organisms.

All the colonizing species are referred to as species pool. With increase in the number of species in the new area, there is a relative decrease in species pool which in turn translates to decrease in the rate of immigration (Dansereau, 65). Consequently, crowding of the island would be an issue to talk about due to scarcity of supplies and resulting into an elevation in the rate of extinction. The model is meant to predict deviations in the rates of immigration and extinction towards the equilibrium. This normally vary depending on the how much the island is endowed with resources as well as the degree at which it is separated from other islands. This can be illustrated in the figure below;

Biogeography and Plate tectonic theory of evolution

Biogeography justifies the plate tectonic theory which is a stronger part of the evolution theory. Examination of fossils had given a hint on how the evolution of certain species took place in various regions of the world such as the Antarctic. These areas during those times were characterized to be on the further north where the climate was characterized by high temperatures. It is from these points that they spread to other parts namely South Asia and Gondwanan continents, Laurasia during the late stages of Paleogene, and then the global distribution. During that dispersal time, it is said that the Indian Ocean was much narrower as compared to its nature today.

The Antarctic was also much close to South America. Nevertheless, to this point, it would be hard to account for the presence of several ancient lineages of perching birds across the continent of Africa. Therefore, one can easily note that the entire process of evolution impacted greatly on the distribution of some sets of species in different parts of the earth thus unveiling a correlation between biogeography and the theory of evolution.

Island biogeography of species

All and sundry can notice that there is no even spread of life and islands across the surface of the earth. The occurrence of this phenomenon is owed to the process of evolution and biogeography acts as the tool that lightens this phenomenon. Data concerning the availability of certain species in different islands and continents revealed through biogeography aid gives out information of almost the same descent and also distinguishes specific patterns of the process of speciation.

Biogeography also explains the process of evolution well when the situation in Australia is analyzed. Before the arrival of human species about over 40, 000 years, Australia was inhabited by over 100 species of animals including; marsupials, Koalas and Kangaroo. However, there were no traces of terrestrial mammals whose line of species is advanced with the likes of horses, wolves, bears, lions, and wolves. Considering the case of isolated islands such as New Zealand and Hawaii, there was a habitation for land animals.

Nevertheless, each of these isolated islands and areas habited several species of birds, plants, and insects which could not be seen in any part of the world except in such like places. Therefore, the existence of extreme and unique environmental conditions in Hawaii, Australia, and New Zealand can best be explained as the formation of life through evolution in isolation from other parts of the planet for millions of years elapsing.

Continental discontinuity of species

Continental biogeography further makes the whole process of evolution understandable. It depicts that all living organisms/creatures have specific adaptations to biotic and abiotic factors in their surrounding habitat (Holly, 112). Even though one can expect that the modes of adaptation influence the same species of organisms to be found in the almost same geographical area such as in Asia, South America, and Africa, all species of living things are distributed discontinuously all around the planet earth.

This kind of discontinuous distribution of species of animals and plants is easily noted in South America as well as in Africa instance, in Africa, there are short-tailed giraffes, monkeys, lions, and elephants while in South America, the story changes due to the presence of long-tailed llamas, monkeys, jaguars, and cougars. It is also in the same way that discontinuity can be observed in the flora of South America as well as North America. This is depicted by the presence of cacti in both cases while in Asia, Africa, and Australia, deserts are characterized by the presence of succulent native kinds of euphorbia that are similar in appearance to cacti but are distinct in several ways. It is in the same way that cacti randomly planted by humans also thrive especially in Australian deserts.

Biogeography best accounts for continental discontinuity of species of living organisms as evolution was underway. We come to note that the major group of mammals seen in the modern world originated from the Northern Hemisphere after which they migrated in three distinct directions. The first direction was to South America through places known as Bering Strait (across the land bridge) and Panama. However, some families of marsupials in South America got extinct due to scarcity of food and competition with their counterparts from Northern America. The second direction was towards Africa through the Strait of Gibraltar while the third direction was to Australia through South Eastern side of Asia (these areas were at one time connected by a mass of land).

Passage through the first direction is illustrated by the fact that Bering Strait was very shallow hence could ease passing of animals as they shifted between the northern continents. Besides, it also shades more light on the current similarity noted in Faunas.

However, after movement to the continents located to the south, a number of barriers isolated them and with time they developed ways of adaptation to their new habitats in a way that show their differences to the present day. Some of those barriers include; Isthmus of Panama which submerged and later isolated the fauna in South America, African fauna was also isolated by Mediterranean Sea and the Northern African desert and also the connection that existed between South East Asia and Australia got submerged leading to isolation of Australian Fauna. After isolation, most of the animals across all the outlined continents have been able indicate an adaptive radiation capability to evolve.

Distribution of islands

Evolution process that led to formation and distribution of islands is also best explained with the aid of biogeography. This study depicts that islands can be categorized into two and this is; continental islands such as Japan and Britain that are traced to have belonged to one continent at one time. The next category is known as oceanic islands such as the islands of Hawaii and Galapagos (Whittaker, 95). Oceanic islands are characterized by distribution of indigenous plants and native animals. Actually, terrestrial mammals are not present in oceanic islands with exception of seals and bats.

Others include fresh water fish and amphibians and in some instances, terrestrial reptiles can be found in oceanic islands but this barely happens (Wallace, 68). Amazingly, evolution of these species exclusively found in oceanic islands happened in such a way that they are not present in any other location on the surface of the earth (endemic). Nevertheless, these species have a number of similarities with other species in other highlands.

Darwins discovery through biogeography

In the study of evolution or in attempts to seek to understand certain things that seem like mysteries on the surface of the earth such as striking difference in flora and fauna and reason for the presence of polar bears in Arctic and penguins in Antarctica. Actually, this brings an important point in the context of this article that biogeography provided foundational basis for understanding the real details underlying the entire process of evolution. In case where island species were so different from others, Darwin came to a conclusion that the inhabitants of the island must have come from the mainland just the same as other species.

This then become the literal explanation of why species present in Galapagos island takes after the ones in mainland (South America) while those found in Cape Verde so much resemble the ones in West African mainland. Darwin also came to infer that deviations in location of climatic zones with time accounts for variation in patterns habitat of various animals. Moreover, Darwins claims or evolution theory is even more eminent with continuous finding of fossils in the same parts of the globe which are traced to have belonged to the ancestors.

Conclusion

In conclusion, this article explains how the study of distribution of species, organisms and geographical ecosystems affirms the theory of evolution. From this article, one thing that is evident is the fact that biogeography provided the basis for discovery and foundational basis for Darwins theory of evolution. This is supported by a number of factors thus making biogeography as a study a very powerful tool of insight as far as evolution is concerned.

Works Cited

Browne, Janet. The Secular Ark: Studies in the History of Biogeography. New Haven: Yale University Press, 1983. Print.

Dansereau, Pierre. Biogeography: An Ecological Perspective. New York City: Ronald Press Company, 1957. Print.

Hollry, Dennis. Biogeography as Evidence of Evolution: Understanding the Discontinuity of Species Distribution. London: Blackwell Publishing, 2009. Print.

Wallace, Arisson. The Geographical Distribution of Animals. London: Macmillan publishers, 1876. Print.

Whittaker, Right. Island Biogeography: Ecology, Evolution, and Conservation. New York: Oxford University Press, 1998. Print.

Discussion

Most parasites become less toxic to their hosts over evolutionary time. According to the scientific research conducted on parasites today, an evolutionary examination concludes that the parasites would virtually be harmless to the principal host organism. This research has been backed up by the scientific notion that it is because the host serves as the environment where the parasite generally survives and sexually copulates (Price, 1980). Consequently, when the parasite causes any toxic harm to its host organism, it would be counterproductive to its survival as well. As a result, the characteristics of the parasite that is relatively harmless to the prime host, for example as found in cats, would be anticipated to evolve. This is because the parasites that behave in that manner would have a better rate of reproduction.

On the other hand, the parasite would equally be anticipated to be rather harmful to the secondary host organism. This is explained by the fact that the parasite will never get to the main host unless the secondary host is consumed by the main host. Subsequently, within the secondary host, the behavior of the parasite that makes the secondary host more at vulnerable risk to being consumed by the primary host would be anticipated to evolve. The parasites that act as a result of that would therefore have a better opportunity of getting to the main host and hence reproducing into it. Therefore, within the secondary hosts, which more often than not comprises rodents such as mice and rats, it is evident that the parasite attacks the hosts nervous system and creates odd modifications in the behavioral characteristics of the host. An example of such an odd modification is illustrated in the infected mice and rats behavior of becoming attracted to the smell of cats instead of being repelled away. This lethal attraction in rats is caused by the infection of Toxoplasma Gondii parasites.

Currently, human beings are equally victims of the evolutionary strategy that is conducted by the parasite on the host. Similar to rats and mice, human beings act as secondary hosts to the parasites. Most infected people fruitfully battle out the parasite, but in others, the nervous system is invaded, thus creating odd behavior in them as well (Roger, Pedro & Gonzalez, 2006).

Hosts Reactions to Parasites

Hosts react to parasites in various ways varying from their behavioral and morphologic characteristics. For instance, plants create certain substances to prevent them from harmful parasites. Vertebrates have intricate and well-advanced immune systems. They produce a corporeal fluid that aims to battle out the parasites in the course of physical contact with them. This exhibits the morphologic characteristics of animals (Tinsley, 1999). Animals are also identified to respond to parasites using behavioral counter actions. For instance, roundworm eggs get collected during the preceding year hatch all together as a whole. Sheep also exhibit behavioral counter actions by avoiding grazing on the open meadow during the spring season. In addition to this, the infected fruit flies consume alcohol to act as self-medication against parasites that are transmitted through the blood. Human beings produce Immunoglobulin E antibodies. These act as resistance to the parasites (Viney, Read, & Chappell 2002).

The Evolutionary Aspects of Parasites

Parasitism is a general form of life that takes place autonomously and numerous times in the course of evolution. More than fifty percent of all living organisms have a minimum of one parasitic period in their life spans. This is equally common in fungi and plants. Furthermore, nearly all independently living animals serve as hosts to one or more parasites (Lewis & Campbell, 2002).

Parasites undergo evolution to counteract the mechanism of their host species. As the consequence of the resistance of the hosts, some parasites evolve adaptations that are precise in certain hosts, therefore specializing until the level where they can infect only one distinct species. This kind of constricted host specialization by the parasites can be costly to them during the evolutionary period though this only occurs when the host species becomes extinct. For this reason, many parasites can infect numerous host species that are more or less strongly interrelated, with diverse rates of accomplishments (Stearns & Hoekstra, 2005).

The counteractive mechanisms in the hosts equally evolve in reaction to the nature of the infections made by the parasites. Hypothetically, parasites may have a benefit in this evolutionary defense mechanism because of their extra fast reproduction timeframes. This is due to the fact that hosts procreate less fast than parasites, and hence have less probability to adjust than how their parasites do during a particular life span (Hurd, Lane, & Chappell, 1998).

In certain cases, parasite species may also co-evolve with their host species. Long-term coevolution from time to time leads to a reasonably firm relationship between the host species and the parasite species which leads to commensalism or mutualism. Equally important is the fact that it is in the evolutionary significance of the parasite that its host flourishes. A parasite may evolve to develop into being less detrimental to its host or a host may evolve to deal with the inevitable existence of the parasite (Webster, 2009). The eradication of certain parasites that coexist with the host can cause the hosts immune systems to become irregular and unbalanced. This can even lead to the point where the parasites non-existence causes harm to the host. For instance, this is illustrated by the actuality that even though animals that are infected with parasitic worms are identified to be evidently harmed, and for that reason parasitized, such infections may also decrease the predominance and outcomes of inflammatory autoimmune diseases in the animal host species, including in human beings (Lively & Dybdahl, 2000).

The co-relationship between parasites and their hosts have huge autoimmunity affiliations in ailments such as Crohns disease and asthma. These theories were proved to be of clinical significance when several patients with Crohns disease and ulcerative colitis were treated with pig whipworm; Trichurus Suis. More than two-thirds of the patients showed improvement. Researchers have begun establishing a secure dosage of human hookworm for asthma patients due to their findings (Clark & Jean, 2012).

The rivalries between parasites have a propensity to favor quicker procreation and as a result this leads to the creation of more dangerous parasites. The parasites whose life span entails the fatality of the host, which involves departing from the current host and then getting into the next, evolve to be more powerful and dangerous even changing the behavior or other characteristics of the host species. This is done to make the host species more susceptible to their predators. The parasites that procreate mainly to the progeny of the preceding host are predisposed to become less dangerous and hence carry out symbiotic mutualism so that their host can procreate more efficiently as well (Hughes, Brodeur, & Thomas, 2012).

References

Clark, D. P., & Jean, N. P. (2012). Molecular biology. 2^nd ed. Waltham, MA: Academic Press.

Hughes, D. P., Brodeur, J., & Thomas, F. (2012). Host manipulation by parasites. London: Oxford University Press.

Hurd, H. Lane, R. P., & Chappell, L. H. (1998). Parasite-insect interactions: reciprocal manipulation. British Society for Parasitology Journal, 116 (35), 48-59.

Lively, C. M., & Dybdahl, M. F. (2000). Parasite adaptation to locally common host genotypes. Nature Journal, 405 (19), 128-145.

Lewis, E., & Campbell, J. F. (2002). The behavioral ecology of parasites. Wallingford: CABI Publishers.

Price, P. W. (1980). Evolutionary biology of parasites. Princeton, NJ: Princeton University Press.

Roger, M. J., Pedro, N., & Gonzalez, L. (2006). Allelopathy: a physiological process with ecological implications. Dordrecht, Netherlands: Springer Publishers.

Rosza, L., Reiczigel, J., & Majoros G. (2000). Quantifying parasites in samples of hosts. Journal of Parasitology, 86 (7) 228-232.

Stearns, S. C. & Hoekstra, R. F. (2005). Evolution: an introduction. Oxford: Oxford University Press.

Tinsley, R. C. (1999). Parasite adaptation to environmental constraints. Cambridge, Cambridge University Press.

Viney, M. E., Read, A. F., & Chappell, L. H. (2002). Parasite variation: immunological and ecological significance. Cambridge University Press.

Webster, J. P. (2009). Natural history of host-parasite interactions. London: Academic Publishers.

A parasite derives nutrients from its host through a mode of feeding known as parasitism. Parasites live inside or on the outside of the hosts body throughout its life cycle. A host can suffer from conditions caused by the parasite in all stages of the parasites life (Webster, 2009). A parasite can affect its host in quite a number of ways depending on the parasites species. Parasites produce some toxic substances that are dangerous to the host. The most devastating effects of a parasite to the host are related to the toxicity of the parasite. Some parasites evolve at a fast rate and therefore making it difficult for scientists to conduct research on the level of toxicity of a parasite over the evolution time. (Webster, 2009). However, a number of experts have argued that the level of toxicity of parasites to their hosts reduces over evolution time. This paper aims at evaluating the relevance of this notion.

Adaptation occurs at every level of an individual organism. However, empirical studies on parasite evolution present a different picture; the toxicity continues to decrease (Viney et al., 2002). Most importantly, some experts argue that the evolution of lower toxicity in response to limited parasite dispersal is a clear indication of adaptation at the group level. The effect of dispersal on reduced parasite toxicity can be understood in terms of adaptation. The process of adaptation is an evolutionary process that has prompted many researchers to develop an interest in studying it. According to Darwins theory of evolution, adaptation is a consequence of natural selection. In this case, the process of adaptation takes place through the action of natural selection (Viney et al., 2002). The process of natural selection is mediated through differential reproductive success and the associated genetic changes of the organism in question. This phenomenon is often passed to the organisms future generations. Increased dispersal reduces a parasites toxicity because dispersal subjects the parasite to different environments (Tinsley, 1999). Some of these environments hamper the production of toxins by the parasite. The reduction in parasite virulence is therefore attributed to increased dispersal (Tinsley, 1999).

The phenomenon of natural selection leads to the molecular evolution and ultimately changes the chemical and biological behavior of parasites. The Red Queen Hypothesis states that biotic interactions are a result of molecular evolution (Stearns & Hoekstra, 2005). According to this theory, species coexist in the ecosystem. However, adaptation is likely to change the manner in which species coexist. Consequently, one species may become more competent than the other. As a result, the less competent species becomes displaced from the system. This theory has been used by a number of scientists to explain the reduction in parasites toxicity on their hosts (Stearns & Hoekstra, 2005). This theory explains the fact that adaptation often alters the genetic material of various species including parasites within the ecosystem. As a result, the species acquires specific genes, which influence the overall outlook depending on the conditions dictated by the environment (Rosza et al., 2000). Consequently, the species may alter its chemical characteristics after some time. For example, toxins that were produced earlier might become irrelevant after the adaptation. Thus, their production or effect lessens over the course of evolution (Rosza et al., 2000). A reduction in the toxicity of parasites can be best explained using this hypothesis.

Biologists have conducted different studies to evaluate a reduction in the toxicity of Encephalitozoon cuniculi owing to changes in its mitochondria over time (Roger et al., 2006). Intracellular parasites undergo a number of cellular and genetic transformations during their lifetime. According to the current data on different genomes, E. cuniculi as a genome generates ATP through substrate-level phosphorylation only (Roger et al., 2006). Proliferating microsporidia have been known to recruit the hosts mitochondria. As a result, this parasite often tops up its ATP requirements by extracting some from its host. It has been found that E. cuniculi has genes that code vector proteins that resemble the hosts ADP/ATP transporters. Lewis and Campbell (2002) compared the sequences of four E. cuniculi ATP transporters to those derived from nucleotide transporters found in plastids and bacterial parasites, and those of previously characterized ATP/ADP translocases (Lewis & Campbell, 2002). The researchers learnt that the four E. cuniculi sequences differed from each other significantly. The researchers launched an investigation in order to understand why the four sequences were different from each other. The researchers used antisera to determine the expression and cellular location of the E. cuniculi transporters (Lewis & Campbell, 2002). The researchers attributed the differences in location and expression of E. cuniculi sequences to adaptation. According to the researchers, E. cuniculi have undergone changes in their genomic composition over time (Price, 1980).

The use of bacterial-like nucleotide transporters (NTTs) to acquire ATP from their hosts is a unique strategy (Price, 1980). This strategy often leads to stiff competition for ATP between the host and E. cuniculi. This competition is sometimes extremely toxic to the host. Other intracellular parasites like Leishmania and Plasmodium have been found to use transporters that are homologous to their hosts proteins (Price, 1980). The study conducted by Price (1980), suggests that microsporidia use NTTs to steal ATP from their hosts. Prices study also suggests that Microsporidia have undergone evolutionary changes leading to changes in the expression and location of NNTs. However, the reasons as to why E. cuniculi has undergone these changes are not clear, but according to Price (1980) this might be due to changes in the ATP pathway in their hosts. The technique used by E. cuniculi to meet its ATP requirements by stealing extra ATP from the host often leaves the host literally starving (Lewis & Campbell, 2002). This is extremely toxic to the host during harsh conditions especially when food is scarce. During such conditions, the parasite significantly benefits because its energy requirements are less than those of the host. The study conducted by Tinsley (1999) suggests that this phenomenon seems to be reducing because E. cuniculi ATP transporters located in the parasites mitochondria normally change their genetic composition.

In another study conducted by Jean and Clark (2012), a completely new method was used to study the effect of evolution on toxicity. The researchers endeavored to evaluate how evolution in the host has contributed to low toxicity in parasites. According to Jean and Clark (2012), infectious diseases significantly influence the demography of humans, plants and animal populations. The hosts resistance to diseases varies with time and in the process affects disease patterns. In a number of host loci, variability has been reported in many instances (Hughes et al., 2012). For example, the manner in which the major histocompatibility complex influences disease expressions is a result of selective forces, which have been imposed by pathogens. It has also been found that at the molecular level, pathogen diversity influences the dynamics of epidemics (Price, 1980). For example, low HIV prevalence in a given region may be due to low genetic variation in that region. Other studies have revealed that there is a negative relationship between the general measure of pathogen diversity and disease incidences (Tinsley, 1999).

Furthermore, advanced genetic engineering studies have shown that there is a negative correlation between disease prevalence and population resistance biodiversity. The relationship between disease dynamics and host population genetic structure has not been properly investigated by genetic engineering experts (Roger et al., 2006). New diseases have continued to emerge due to pathogen evolution. Thus, it is paramount to study how evolution in the host has contributed to low toxicity in parasites. According to Lively and Dybdahl (2000), the current models examining host-pathogen co-evolution have been shaped by the gene for gene paradigm.

In addition, this theory indicates that the pathogen virulence gene and a resistant gene in the host must be present at the same time for a resistant reaction to take place. Lively and Dybdahl (2000) argue that the strength of the positive relationship between host resistance and pathogen virulence in the Linum Melampsora interaction, explains the potential for host variation to determine evolutionary trajectories of pathogen populations (Webster, 2009). Furthermore, pathogens in a low diversity host population are not normally favored by evolution. Lively and Dybdahl (2000) conclude that the parasite systems of plant and animal parasite systems play a major role in the transmission of diseases to the host. Pathogen isolates that resistant genes fight to overcome affect the rate of spore production. A reduction in spore production occurs when resistant genes are attacked by virulent pathotypes. From the study conducted by Webster, it can be noted that some hosts may undergo evolutionary changes which limit the toxicity of parasites (Webster, 2009). These findings support the notion that the toxicity of parasites to their hosts reduces over evolution time. This study is particularly important because it evaluates this phenomenon from the hosts perspective.

Furthermore, insect-borne parasites are known to adapt to changes in temperature and nutrition within the arthropod vector by lifecycle differentiation. Insect-borne parasites normally face immunological attacks and some nutrient deficiencies while in the arthropod vector (Webster, 2009). Most importantly, these parasites use specific cues to initiate changes in temperature and PH in the hosts body (Hurd et al., 1998). These changes are aimed at challenging the hosts by making them vulnerable. Molecules that are involved in the generation of these cues continue to evolve while there has been a significant reduction in the toxicity caused by insect-borne parasites owing to evolutionary changes. African trypanosomes, which are protozoan parasites, are some of the most harmful parasites known to man (Lewis & Campbell, 2002). These parasites are often transmitted by tsetse flies, and this requires the formation of bloodstream stumpy forms. This phenomenon is genetically predetermined. A stumpy inducing factor has been known to induce the formation of stumpy forms. When ingested by tsetse flies, stumpy forms differentiate into procyclical forms. Proteins associated with differentiation (PAD) are controlled by predetermined genetic factors. Tinsley (1999) argues that these genetic factors have undergone numerous changes as the parasites attempt to adapt to changes in the environment. Consequently, some of the changes that occur are overwhelmed by changes in the ecosystem. As a result, there has been a reduction in the toxicity of trypanosomes (Lewis & Campbell, 1980).

Recent research has found that the effects of a parasite on the host vary widely. The most devastating effects of a parasite to its host are related to the toxicity of the parasite. The study conducted by Hurd, Lane, and Chappel (1998) revealed that increased dispersal reduces a parasites toxicity because dispersal subjects the parasite to different environments. Some of these environments hamper the production of toxins by the parasite in question. This approach has also been used to explain a reduction in parasite virulence. Another study conducted by Hurd et al. (1998) used the Red Queen hypothesis to explain how the phenomenon of natural selection leads to the molecular evolution and ultimately changes the chemical and biological behaviors of parasites. Red Queen Hypothesis states that biotic interactions are a result of molecular evolution (Tinsley, 1999).

In addition, the study conducted by Hurd et al. (1998) indicates that the use of bacterial-like nucleotide transporters (NTTs) to acquire ATP from hosts is a unique strategy. This strategy often leads to stiff competition for ATP between the host and the parasite. This competition is sometimes extremely toxic to the host. Other intracellular parasites like Leishmania and Plasmodium have been found to use transporters that are homologous to their hosts proteins (Tinsley, 1999). The study conducted by Hurd et al. (1998) suggests that this phenomenon seems to be reduced owing to evolutionary changes in the genetic composition of E. cuniculi ATP transporters located in the parasites mitochondria.

On the other hand, Stearns and Hoekstra (2005) used a different approach to explain this phenomenon. The researchers endeavored to evaluate how evolution in the host has contributed to low toxicity in parasites. From the study conducted by these researchers, it can be noted that some hosts may undergo evolutionary changes, which limit the toxicity of parasites. These findings support the notion that the toxicity of parasites to their hosts reduces over evolution time. This study is particularly important because it evaluates this phenomenon from the hosts perspective.

In conclusion, parasites are known to adapt to changes in temperature and PH in the arthropod vector. These parasites use specific cues to initiate changes in temperature and PH in the hosts body or the hosts environment. This is aimed at challenging the hosts or making them vulnerable. Price (1980) argues that genetic factors have undergone numerous changes as the parasites attempt to get used to their new environment. In addition to that, some of the genetic changes that occur are overwhelmed by changes in the ecosystem (Price, 1980). As a result, there has been a reduction in the toxicity of trypanosomes. Thus, it can be argued that the toxicity of parasites to their hosts reduces over evolution time.

References

Clark, D. P., & Jean, N. P. (2012). Molecular biology. 2^nd ed. Waltham, MA: Academic Press.

Hughes, D. P., Brodeur, J., & Thomas, F. (2012). Host manipulation by parasites. London: Oxford University Press. Web.

Hurd, H. Lane, R. P., & Chappell, L. H. (1998). Parasite-insect interactions: Reciprocal manipulation. British Society for Parasitology Journal, 116 (35), 48-59.

Lively, C. M., & Dybdahl, M. F. (2000). Parasite adaptation to locally common host genotypes.Nature Journal, 405 (19), 128-145. Web.

Lewis, E., & Campbell, J. F. (2002). The behavioral ecology of parasites. Wallingford: CABI Publishers. Web.

Price, P. W. (1980). Evolutionary biology of parasites. Princeton, NJ: Princeton University Press.

Roger, M. J., Pedro, N., & Gonzalez, L. (2006). Allelopathy: a physiological process with ecological implications. Dordrecht, Netherlands: Springer Publishers.

Rosza, L., Reiczigel, J., & Majoros G. (2000). Quantifying parasites in samples of hosts. Journal of Parasitology, 86 (7) 228-232. Web.

Stearns, S. C. & Hoekstra, R. F. (2005). Evolution: an introduction. Oxford: Oxford University Press.

Tinsley, R. C. (1999). Parasite adaptation to environmental constraints. Cambridge: Cambridge University Press.

Viney, M. E., Read, A. F., & Chappell, L. H. (2002). Parasite variation: immunological and ecological significance. Cambridge University Press. Web.

Webster, J. P. (2009). Natural history of host-parasite interactions. London: Academic Publishers.

The article Molecular Insights into Classic Examples of Evolution attempts to demonstrate how modern advances in molecular biology are challenging the scope of our understanding regarding the concepts of evolution and survival. Current research, as discussed by the symposium speakers explicitly cited in this article, reveals that genetics plays a fundamental role in evolution science and it is indeed the mutation of genes that actually allows organisms to evolve and develop survival tactics. The author cites a classic example of how the common garter snakes have evolved over a short period of time to be able to gain an advantage over their major prey, the newts, even though the prey produces a potent neurotoxin that is capable of killing other animals as well as humans (Hlodan 264). In a sense, the article attempts to draw a correlation between genes and evolution on one side and the ability of organisms to survive within their own natural environments on the other.

The author of this article, through citing presentations made by various speakers in the symposium, also attempts to demonstrate how viruses continue to challenge our basic insights into the evolution and how scientists can make important inferences that may lead to medical breakthroughs by studying how the viruses evolve within our bodies. Indeed, the author uses the examples of the human immunodeficiency virus (HIV), dengue virus, and influenza viruses to demonstrate how RNA-type viruses evolve to viral DNA, thus rendering unsuccessful any attempts made by scientists to control or kill them. The HIV virus, for instance, evolves at a fast pace from a viral RNA to make Viral DNA, in the process producing many variants of HIV within and among victims. Indeed, it has been revealed in the article that &the HIV envelope gene accumulates substitutions at a rate of approximately one percent a year [while] the average eukaryotic or prokaryotic gene accumulates that much substitution in about 4 million years, and ribosomal RNA takes approximately 50 million years (Hlodan 265). It should be remembered that these mutations assist the viruses to survive in their natural environments.

The discussion in the article continues by examining how coloration in some animals such as the Oldfield mouse affords them the opportunity to survive in their natural environments by enabling them to camouflage and hide from their predators. A butterfly species commonly found in East Africa has evolved false eyespots on its wings to distract its predators away from where its vital parts are located (Hlodan 266-277). It is worth noting that current research done by the speakers during the symposium reveals that genes have a fundamental role to play in triggering the evolution of these color variations.

On personal reflection, it is indeed true that my views on evolution and nature have dramatically changed since enrolling in this course. My knowledge on the topic has expanded, more so in realizing the critical role played by evolutionary perspectives to our survival. It is interesting to note that our environment triggers the capacity of our genes to mutate and occasion some adaptive processes to enhance our survival. The article, in particular, has expanded my knowledge on HIV and why there is currently no cure for the virus. A probable treatment strategy for HIV, in my view, would be for scientists to develop mechanisms that will prevent the HIV envelope gene to evolve from RNA virus to viral DNA. However, this observation is debatable.

Works Cited

Hlodan, D. Molecular Insights into Classic Examples of Evolution. Bioscience 61.4 (2011): 264-267.