Investigation of latitudinal clines for Dca genotype and wing size in Drosophila melanogaster

Drosophila melanogaster is a cosmopolitan species that spread over temperate regions. It is a widely used model organism to study the evolutionary dynamics associated with genetic and environmental heterogeneity in a broad geographical distribution area. Many characters are known that are exhibit a latitudinal cline in D. melanogaster. These clines are widely interpreted as an adaptive result of spatially varying selection. Also body size is a known character for strong latitudinal cline. Wing size that a decisive parameter for body size are frequently used in the study of local adaptation and the clinal variations. In this study, in order to test the hypothesis that the wing size shows a latitudinal cline, variation of wing size were investigated in natural populations of D. melanogaster which were collected from three different latitudes, Turkey, Ukraine and Russia. The latitudinal variation of wing size and also seasonal variation has been investigated and the relationship has been investigated with the Dca gene, which is thought to be a candidate gene related to wing size. In this study, 116 lines collected from Turkey, 51 lines collected from Russia and 31 lines collected from Ukraine, which were subjected to 20 generations of full-sib mating for inbreeding, were used for determination of latitudinal and seasonal variations of the wing size and shape. The results show that wing size show a strong latitudinal cline, and that populations differ as a result of adapting to temperature with varying latitudes. Besides, the wing size also varies according to the season in which the populations are collected. In addition, it has been found that Dca gene shows also a latitudinal cline. However, significant relationship was not found between the variations of the wing size and the Dca allele polymorphisms.