Narrow-Headed Voles Species Complex (Cricetidae, Rodentia): Evidence for Species Differentiation Inferred from Transcriptome Data

Abstract

The narrow-headed vole complex includes two cryptic species, Lasiopodomys raddei and L. gregalis, and three allopatrically-distributed lineages with obscure taxonomic ranks within the latter. Based on the RNA-seq data of 12 specimens, the current study aims to find the molecular mechanisms of intraspecies differentiation and, in particular, reproductive isolation between analyzed groups. According to the results of the GO-enrichment analysis, about a hundred biological processes associated with genes with contrasting SNPs for L. gregalis and L. raddei were identified. Among them, processes of interspecific interactions, defense responses, responses to external stimuli, and the perception of chemical stimuli and smell were identified, indicating the likely existence of pre-copulatory behavioral and physiological mechanisms that contribute to reproductive isolation between cryptic species. An evaluation of the ratio of non-synonymous substitutions to synonymous ones showed evidence of selection in L. raddei compared to L. gregalis for a large part of the analyzed genes. Among the analyzed genes, genes with both weakening and intensifying selection were found.