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Genomic stress influence on wing size and shape in Drosophila subobscura

Dijana Cvijetić

Regional Center for Talented Youth Belgrade II, Serbia, dijanachl@gmail.com

1. Introduction clear sexual dimorphism in this species (Picture 2). There is
significant interaction between sex and groups (Table 1).
Inbreeding, mating between close relatives, is a genomic
stress that may disrupt the stability of the genome [1]. This Effect df MS F
phenomenon occurs in nature, especially in situations of group 3 23606 37.7 ***
habitat fragmentation caused by anthropogenic influence, sex 1 492693 787.2 ***
global climate changes and rapidly growing pollution. In group x sex 3 4089 6.5 ***
those cases, population could be isolated for a certain Error 481 626
period, which would lead to mating closely genetically
related individuals [1]. Inbreeding results in homozygosity, Table 1. Two-way ANOVA on wing size (CS) of
and has both positive and negative effects on whole range individuals from four groups and both sex
of traits, including morphological traits and fitness
components [2].

The aim of this study was to evaluate influence of
experimentally increased homozygosity, as genomic stress,
after 14 generations of full-sib inbreeding treatment in
laboratory conditions on Drosophila wings morphological
traits.

2. Materials and methods
Picture 2. Mean values of centroid size for all experimental
In this experiment, highly inbred lines of D. subobscura, groups and both sexes
originating from two ecologically and topologically distinct MANOVA showed no difference in wing shape between
habitats (Botanical Garden in Belgrade and Sicevo gorge) experimental groups, as a result of different genes and
were used, knowing that they possess a certain degree of genetic pathways involved in development of these wing
genetic differences due to their different evolutionary morphological characteristic [3], and which is consistent
histories. Beside homozygotes from inbred lines, with results of previous studies.
heterozygotes from direct and reciprocal crosses between
these populations were used. For analysis of phenotypic 4. Conclusion
variability of the wings males and females were separated.
The right wing of each fly was fixed and the digital Understanding nature of phenotypic variation is important
photograph was taken. Images were landmarked with 13 aspect of evolutionary biology. One of the reasons why
landmarks (Picture 1). Wing size was examined using homozygous individuals have smaller wings may lie in fact
centroid size (CS) and shape was examined using weight that more recessive genes are expressed in phenotype than
matrix (wm). Differences in CS were tested with ANOVA, expected, which can lead to lower performances in
and the ones in wm with MANOVA. individuals as well as in populations.

Another explanation is heterozygote superiority, theory
which states that higher level of heterozygosity increases
fitness of an individual, and since the wing size is closely
related to a fitness of an individual, obtained results are in
concordance with this theory.

5. References

Picture 1. Right wing of D. subobscura with 13 landmarks [1] L. F. Keller, D. M. Waller, 2002: Inbreeding effects in
wild populations. Trends in Ecology & Evolution, 17: 231.
3. Results and discussion [2] M. Lynch 1997: Inbreeding depression and outbreeding
depression. In: Genetic effects of straying of non-native fish
The results for wing size showed significant difference hatchery fish into natural populations. W. S. Grant (editor).
between homozygote and heterozygote groups (Table 1). U.S. Dep. Commer., NOAA Tech Memo.
Heterozygous individuals have larger wings than [3] V. P Carreira, I. M Soto, J. Mensch, J. J Fanara, 2011:
homozygous (Picture 2). Also, between sexes is significant Genetic basis of wing morphogenesis in Drosophila: sexual
difference: males have smaller wings than females, due to dimorphism and non-allometric effects of shape variation.
BMC Developmental Biology, 11: 32.