Drosophila melanogaster Populasyonlarında Kromozomal İnversiyonların İklim Değişimine Adaptasyon ve Çevresel Streslere Verilen Cevap ile İlişkisi

Abstract

Chromosomal inversions have been described in many organisms and are known to affect the adaptive responses of organisms. Inversion frequencies show spatial and temporal variations in populations. Inversion polymorphisms, which can be associated with climatic and geographical variables, are suggested as markers through which the genetic effects of climate change can be followed. It is known that one of the most important effects of climate change is temperature. Environmental variables such as drought and salinity are also important variables caused by climate change. It will be difficult for organisms to cope with these rapid and strong environmental changes. Therefore, the existence of local adaptation in populations living in environments were aridity and salinity stresses are severe can be considered as strong evidence that adaptive processes may occur in populations that have lesser or not encountered these stresses. To test this hypothesis, the frequency of In(2L)t, In(3R)K and In(3R)Payne inversions, which are closely related to environmental variables, was calculated in five natural populations of Drosophila melanogaster collected from arid, semi-arid and humid regions. Additionally, the desiccation tolerance and the development time and survival at different salt concentrations were measured of these populations. The relationship between climatic and geographical variables and genotype and phenotypic characters was analyzed. Thus, it was aimed to investigate the relationship between inversions and aridity, and also salinity stress. The results revealed a significant relationship between In(2L)t and desiccation tolerance. Lines carrying the inversion coped better with desiccation stress. In addition, desiccation tolerance shows a positive relationship with temperature and a negative relationship with humidity and longitude. The positive relationship between desiccation tolerance, In(2L)t and temperature is in concordance with the positive relationship between In(2L)t frequency and average monthly temperature. In(3R)P inversion showed a strong altitudinal cline, were the inversion frequency decreasing as the altitude increased. No relationship was found between the inversions and salt tolerance.