Abstracts (first author)
Genomic pattern of selection for ecologically important trait - transcriptome analyses of the bank vole artificial selection experiment
Although, a response to selection at the genomic level has been investigated for some traits, little is known about the genomics of adaptation in ecologically important traits in vertebrates. Here we compared transcriptomes of the bank voles (Myodes glareolus) selected for high swim-induced aerobic metabolism (A) with unselected controls (C). In 13th generation of selection, voles from 4 replicate A lines achieved 48% higher max rates of oxygen consumption than those from 4 C lines (means±SD; A:5.32±0.64, C:3.59±0.57 mlO2/min) and differed in several other morphophysiological and behavioral traits. Our aim was to characterize the differences in allele frequencies and the differences in expression level between A and C lines, and thus pinpoint genes contributing to phenotypic diversification. Using Illumina paired-end sequencing and de novo transcriptome assembling we constructed reference liver and heart transcriptomes. Sequences obtained for each line from pools of liver and heart RNA were mapped to the reference transcriptomes to detect SNPs and measure the expression level. On average 33.5 and 29.3 mln 100 bp reads per line were obtained for liver and heart respectively, which allowed reliable polymorphism detection in over 7 000 genes resulting in more than 80 000 SNPs. About 1 600 of these SNPs showed allele frequency ranges which did not overlap between A and C lines, about 15% more than obtained from simulations assuming the differentiation purely by drift. However, the average differences in frequencies were similar for simulations and the experiment. We also identified a modest number (10 in heart and 45 in liver) of genes that showed more than two-fold differences in expression between A and C lines. Our results show that the rapid phenotypic diversification is accompanied by only minor changes in allele frequencies or expression level making the presence of genes of large effect unlikely and indicating a highly polygenic basis of the selected trait.