Efekti B hromozoma na genetičku varijabilnost i strukturu populacija žutogrlog miša Apodemus flavicollis (Mammalia, Rodentia)
Effects of B chromosomes on genetic variability and population structure in yellow-necked mouse Apodemus flavicollis (Mammalia, Rodentia)
AuthorsAdnađević, Tanja B.
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B chromosomes (Bs) are supernumerary to the standard set of chromosomes characterized with dispensable nature. Studies on various species, showed that they are not inert, with expression of their effects on different levels from molecular to population level. One of the species from genus Apodemus with B chromosomes, yellow-necked mouse Apodemus flavicollis, is widespread in Palearctic. In order to determine effects of Bs, four populations of A. flavicollis from localities in Serbia, differing in both topological and ecological conditions, as well as frequency of Bs, were examined. Genotyping was done by AFLP (Amplified Fragment Lenght Polymorphism) multiloci method, and 14 primer combinations produced 471 marker. We detected significantly different level of genetic diversity and differentiation between studied populations. Greatest genetic diversity was detected for Fruška gora population, settled in locality with optimal condition for this species. Band based approach estimated greatest genetic differencies between individuals with Bs, in comparison with individuals without Bs, on interpopulation as well as intrapopulation level. Allele frequency based approach did not detect difference between individuals with and without Bs, but it showed difference in alelle frequencies between these two groupes. Partitioning of genetic variability showed that majority of genetic variability is distributed on interpopulation and individual level. Genetic differencies between individuals with and without Bs were not detected. Spatial analysis of molecular variance confirmed high level of genetic differentation based on locality, while lack of correlation of genetic and geographic distances showed that population are not differentiated due to spatial separation. In this case, high level of genetic differentation detected between populations could be explained by local adaptation. Total of twelve loci were detected as loci under selection or close to loci under selection. Three of these loci were detected in all populations, while remaining nine were unique to either population with lower frequency (Fruška gora) or populations with higher frequency of Bs (Tara, Devojački bunar and Lisine). Considering the fact that population are settled on topologicaly and ecologicaly different habitats, we assumed existance of different selection preassures based on the optimality of habitat for this species. Analysis of assosiation of environmental variables ecologicaly important for this species with AFLP markers showed that the greatest number of associations was detected for two variables that could influence population dynamics of A. flavicollis, by affecting availability of preferred food and timing of reproduction. Selection pressures imposed by duration of winter and summer could represent main factors of Bs frequency variation at intrapopulation and interpopulation level. Effect of Bs on genetic diversity and differentiation was not detected in analyzed populations. Ecologically based selection led to adaptation of populations to different habitats, directly acting on mechanism of Bs transmission, favoring individuals with Bs in populations settled in habitats suboptimal for this species. It is possible that epistatic or very small additive effects of Bs are more effective in suboptimal environments, but their epigenetic effects, like modification of the expression of certain genes, could not be excluded either. In this case Bs can be considered as adaptive, confirming heterotic model of B chromosomes maintenance in populations from Serbia.
Keywords:Apodemus flavicollis; AFLP; B chromosomes; Population genomics; Selection; Adaptation
- Genetička raznovrsnost u prirodnim populacijama – uloga B hromozoma (RS-143011) (-)
- Genetic and phenetic diversity in natural populations across different environments - contribution of B chromosome polymorphism (RS-173003)
Belgrade: University of Belgrade, Faculty of Biology (2012): 1-111[ Google Scholar ]