Post-Crossing Mutations in Drosophila Flies of Generations F1 and F2

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Table of Contents

Abstract
Introduction
Materials and Methods
Results
Discussion
Reference List

Abstract

The current research focused on the genetic peculiarities of Drosophila flies and used pairings of mutated and wild-type flies to answer some questions. Drosophila flies were paired in vials and F1 and F2 generations were derived from parental flies. The results of the research proved the scholarly idea that P and F1 flies displayed far fewer mutations than F2 ones, which is due to the genetic peculiarities of Drosophila flies’ development.

Introduction

Drosophila Flies Genetics Background

The study of various forms of life on Earth is often started in laboratory conditions before it goes to the wildlife. Scholars like Ernst (2000, p. 187), Greenspan (2004, pp. 212 – 213), and Peters (2010) claim that Drosophila flies serve as the best samples for laboratory tests of various scholarly hypotheses. The reasons for this fact are numerous and include the easy access to supplies of these flies, the short life cycles of their generations, and the quite interesting genetic inheritance patterns that Drosophila flies display (Peters, 2010). Apart from being rather widely used as research samples, Drosophila flies also present a subject of high interest themselves as their cross procedures can provide intriguing and scholarly valuable results (Ernst, 2000, pp. 196 – 197). Thus, the current research paper also focuses on Drosophila flies and the genetic changes that these insects go through across generations.

Previous Scholarly Views

Thus, the major idea that scholars like Ernst (2000, p. 187), Greenspan (2004, pp. 212 – 213), Ladiges et al. (2009, pp. 129 – 130 ), and Peters (2010) agree on is that Drosophila flies are invaluable samples for genetics tests of any complexity and purpose. Discussing the genetic peculiarities of the flies themselves, scholars like Ernst (2000, p. 189) and Greenspan (2004, p. 219) single out the short life cycles of Drosophila flies and the drastic changes in their morphological, or physical characteristics that can be observed in generation 2 (F2) is the parental generation (P) flies crossed represented different mutant species of Drosophila and the generation 1 (F1) species were rather similar in their characteristics.

Peters (2010) singles out eye color, body color, and cross veins as the major physical traits changed in the process of crossing various mutant species of Drosophila flies. Interestingly, this author points out that the major eye colors for Drosophila flies include brown, sepia, cinnabar, white, and vermillion, while bodies can be black, yellow, and ebony types. As for cross-veins, Peters (2010) singles out Drosophila flies that have cross veins and those that do not have them.

Research Question

Thus, since the genetics of Drosophila flies, is, first of all, focused on the physical characteristics of the test samples, it is quite reasonable to research if the eye color, body-color, and crossvein types of the Drosophila fly studied during the experiment coincide with the theoretically grounded ideas by Peters (2010), Ernst (2000, p. 189), Greenspan (2004, p. 219), and other scholars regarding this point. So, the research question for the current paper is:

Which mutations can be observed in F1 and F2 Drosophila flies compared to their parents P generation of wild flies (with specific emphasis on eye and body color, cross veins, wing sizes, and bristles)?

Materials and Methods

Materials

The materials used for the currently discussed research included, first of all, the samples of the Drosophila flies, both the wild type and the one with certain mutations. For the conduct of the very experiment, two vials were provided, one with the male Drosophila flies and another one with female ones. The food vials were provided for the purpose of pairing the fly samples for the further process of mating and F1 flies’ development. Each vial was labeled properly to identify the flies in it, as well as students responsible for the project. Foam stoppers were used to close the vials and avoid the loss of any Drosophila flies.

Methods

The methodology of the very test of Drosophila flies included several distinct steps. The experiment began by providing the necessary free space for working purposes. After this, the vials with Drosophila flies were distributed to all students. At the same time, the vials with food were provided for the further pairing of male and female flies in them. As the P flies were paired, the generation F1 of Drosophila flies was produced. The parent flies were then killed with ethanol added to their vials and the observations of the process were recorded. Next, F1 flies were decanted in a separate vial to observe their mating process and produce F2 flies. Finally, the F1 was killed by adding alcohol to their vials and F2 flies were observed and their characteristics of major interest were analyzed.

Results

Thus, Table 1 reflects the findings for F1 generation Drosophila flies tested:

Table 1. F1 generation flies’ traits

Cross of male 4-trait & female wild type					Cross of female 4-trait & male wild type
Male (86)		Female (72)			Male (33)		Female (67)
Red eyes	86		Red eyes	72	Red eyes	1		Red eyes	67
Lozenge eyes	–		Lozenge eyes	–	Lozenge eyes	32		Lozenge eyes	–
Grey body	69		Grey body	57	Grey body	7		Grey body	46
Yellow body	17		Yellow body	15	Yellow body	26		Yellow body	20
Ebony body	–		Ebony body	–	Ebony body	–		Ebony body	1
Normal wings	86		Normal wings	72	Normal wings	33		Normal wings	67
Vestigial wings	–		Vestigial wings	–	Vestigial wings	–		Vestigial wings	–
Normal cross veins	86		Normal cross veins	72	Normal cross veins	3		Normal cross veins	58
Cross veins less	–		Cross veins less	–	Cross veins less	30		Cross veins less	9
Normal bristles	86		Normal bristles	72	Normal bristles	9		Normal bristles	62
Forked bristles	–		Forked bristles	–	Forked bristles	24		Forked bristles	5

The above table reveals that two crosses that took place at the first experiment stage to produce F1 flies bring quite similar results to all fly populations. In particular, only 32 F1 male flies in the cross of female 4-trait & male wild type have lozenge eye color, while all the remaining species have the normal red color of eyes.

At the same time, the same cross displays other variations not observed in the samples from the cross with the male dominant gene. In particular, after the cross of female 4-trait & male wild type flies were obtained with both forked and normal bristles, with and without cross veins, and with three body color types.

Respectively, Table 2 represents the results for the F2 flies as retrieved during the second stage of the experiment. A greater variety of traits can be observed in F2 flies if compared to P or F1 ones. Practically all the types of eye color, body color, wing size, cross-veins, and bristles are observed in F2 flies, with the only exception being the absence of vestigial wings in a female sample of F2 flies produced after the cross of female 4-trait & male wild type.

One more interesting feature of the results for F2 generation flies is the almost equal distribution of the physical characteristics among the male and female fly samples. The deviations from this equality are observed mainly due to the unequal number of female and male flies produced after the P cross and F1 fly cross. Table 2 also provides a piece of supporting evidence to the idea derived from Table1. In other words, the domination of the female genes in Drosophila flies crosses can be observed. It is displayed by the greater numbers of female flies derived as a result of every cross carried out, as well as in stronger manifestations of various mutation in female fly samples of F2 generation than in the similar male samples produced during the same experiment:

Table 1. F2 generation flies’ traits

Cross of male 4-trait & female wild type					Cross of female 4-trait & male wild type
Male (73)		Female (90)			Male (90)		Female (98)
Red eyes	51		Red eyes	73	Red eyes	60		Red eyes	57
Lozenge eyes	22		Lozenge eyes	17	Lozenge eyes	30		Lozenge eyes	41
Grey body	34		Grey body	70	Grey body	45		Grey body	46
Yellow body	31		Yellow body	15	Yellow body	43		Yellow body	51
Ebony body	8		Ebony body	5	Ebony body	2		Ebony body	1
Normal wings	72		Normal wings	89	Normal wings	87		Normal wings	98
Vestigial wings	3		Vestigial wings	1	Vestigial wing	3		Vestigial wings	–
Normal cross veins	52		Normal cross veins	80	Normal cross veins	59		Normal cross veins	60
Cross veins less	21		Cross veins less	10	Cross veins less	31		Cross veins less	38
Normal bristles	59		Normal bristles	82	Normal bristles	72		Normal bristles	75
Forked bristles	14		Forked bristles	8	Forked bristles	18		Forked bristles	23

Discussion

So, the findings of the currently discussed experiment are rather interesting, especially from the viewpoint that they fully conform to the previous research views discussed above. Thus considering F1 flies, one cannot but mention the poor variety of their traits. In the results of the male 4-trait & female wild-type cross, there are only one eye color variety, two body color types, and all the flies are uniform in their wing sizes, bristle traits, and normal cross veins. The female 4-trait & male wild type cross adds only one eye color to the variety, while the rest of the results conform to the ideas by Peters (2010), Ernst (2000, p. 189), Greenspan (2004, p. 219), and Ladiges et al. (2009, pp. 129 – 130 ), who argue that F1 is the generation that displays little mutation variety in its physical traits.

F2 flies present a wider variety of traits, and this fact also fits the above presented theoretical framework for the experiment. According to Peters (2010), Ernst (2000, p. 189), Greenspan (2004, p. 219), and Ladiges et al. (2009, pp. 129 – 130 ), F2 flies acquire more diverse traits as a result of more numerous mutations taking place at the genetics level. The results from Table 2 prove this point, as one can observe two eye colors for all F2 flies’ groups, three types of body color, and all possible variations in wing size, bristle form, and cross veins. An interesting implication of the results is that female genes tend to have more influence on flies’ sex determination, which is especially evident in crosses with the dominant female fly species and represented by Figure 1:

Figure 1. Punnett diagram for F2 flies

	Female
Male		RG	RY	LG	LY	WC	WB
	RG	RV	RY	GCl	CV	YG	RY
	RY	FG	RY	ClB	BL	RG	RY
	LG	RG	YV	LG	CV	RG	RG
	LY	RG	CV	RY	LY	WC	WY
	WC	RG	CV	LW	LY	WC	WC
	WB	RG	RG	WB	CV	WB	CV

Note:

R – red eyes
L – lozenge eyes
G – grey body
Y – yellow body
E – ebony body
W – normal wings
V – vestigial wings
C – cross veins
Cl – cross veins less
B – normal bristles
F – forked bristles

Thus, the above discussion can be summarized by the set of the following statements. First of all, the results presented in the respective tables show that F1 flies display few mutations as compared to P generation ones, while the F2 generation flies present the wider field for consideration as their mutations are more numerous and diverse. Second, the results of the current research properly fit in the theoretical framework formed by the views of previous scholars on the genetic peculiarities of Drosophila flies. Finally, the results of the current research allow answering its major question by saying that F1 and especially F2 flies experience mutations of all types in the area of physical characteristics including eye and body color, wing size, bristle form, and the presence or absence of cross-veins, and these mutations are more evident in F2 flies.

Reference List

Ernst, W. (2000) Earth systems: processes and issues. Cambridge University Press.

Greenspan, R. (2004) Fly pushing: the theory and practice of Drosophila genetics. CSHL Press.

Ladiges, P. et al. (2009) Biology: An Australian Focus. McGraw-Hill Australia.

Peters, D. (2010) Drosophila genetics explained. Helium. [online] HM. Web.

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