Drosophila Melanogaster’de Coğrafi ve Mevsimsel Diyapoz Değişimi ve İnsülin-Benzeri Reseptör (Inr) Polimorfizmi ile İlişkisinin Araştırılması

Abstract

Reproductive diapause is an adaptive life history trait, which is related to aging, longevity, fecundity and various stress responses in Drosophila melanogaster. Diapause allow survival in difficult environments and affected by climatic conditions, also demonstrating latitudinal and seasonal variations. Parallel clines of diapause phenotype in North America and Australia suggest that adaptation for diapause is similar in these regions. This study aims to test the hypothesis ‘diapause shows parallel adaptation’ by investigating the diapause frequency in different natural populations from Turkey, Ukraine and Russia belongs to a latitudinal cline. Aside from latitudinal variations, seasonal variations in diapause were also examined. Additionally, the study investigated the relation between diapause frequency and the allels of InR gene, known as insulin-like receptor gene and shown as a strong candidate gene for diapause. The possible relationship between diapause phenotype and Wolbachia infection, which is known to affect several life history traits, is also examined. Finally, the study analysed the correlation between the climatic variables of the geographical regions of the populations and diapause frequency, allel polymorphisms as also with Wolbachia infections. In this study, 46 lines and 59 lines collected from Turkey in 2014 and 2015, respectively, 36 lines collected from Russia and 2 lines collected from Ukraine, which were subjected to 20 generations of full-sib mating for inbreeding, were used for determination of diapause frequencies and InR polymorphisms. Wolbachia infection status of 59 lines, collected from Turkey in 2015, has been determined. Results provide strong evidence that the diapause frequency did not display a parallel cline with America and Australia in this geographical gradient and that the geographic variation of the diapause phenotype is not just an adaptive trait related to climatic variables. In addition, the significant relationship between season and diapause indicated a presence of diapause frequency fluctuations within the population. On the other hand, the InR allele polymorphism was found to produce a latitudinal cline without a relation to diapause. This result shows that InR gene is a functional gene region and is under selection pressures in different geographical regions. There was no significant relationship between Wolbachia infection and diapause frequency.