Abstract
Genetic divergence is impacted by many factors, including phylogenetic history, gene flow, genetic drift, and divergent selection. Rotifers are an important component of aquatic ecosystems, and genetic variation is essential to their ongoing adaptive diversification and local adaptation. In addition to coding sequence divergence, variation in gene expression may relate to variable heat tolerance, and can impose ecological barriers within species. Temperature plays a significant role in aquatic ecosystems by affecting species abundance, spatio-temporal distribution, and habitat colonization. Recently described (formerly cryptic) species of the Brachionus calyciflorus complex exhibit different temperature tolerance both in natural and in laboratory studies, and show that B. calyciflorus sensu stricto (s.s.) is a thermotolerant species. Even within B. calyciflorus s.s., there is a tendency for further temperature specializations. Comparison of expressed genes allows us to assess the impact of stressors on both expression and sequence divergence among disparate populations within a single species. Here, we have used RNA-seq to explore expressed genetic diversity in B. calyciflorus s.s. in two mitochondrial DNA lineages with different phylogenetic histories and differences in thermotolerance. We identify a suite of candidate genes that may underlie local adaptation, with a particular focus on the response to sustained high or low temperatures. We do not find adaptive divergence in established candidate genes for thermal adaptation. Rather, we detect divergent selection among our two lineages in genes related to metabolism (lipid metabolism, metabolism of xenobiotics).
Highlights
Within species genetic divergence can be influenced by multiple factors, including phylogenetic history, gene flow, genetic drift, and divergent selection [1]
In order to better understand the adaptive processes that may have led to such ecological speciation, knowledge of adaptive diversification among disparate populations within species and the underlying genetic variation is of essential importance
We identified signatures of divergent selection in genes related to lipid metabolism and metabolism of xenobiotics
Summary
Within species genetic divergence can be influenced by multiple factors, including phylogenetic history, gene flow, genetic drift, and divergent selection [1]. The utilization of comparative transcriptomics allows us to assess the contribution of particular stressors to expression and sequence divergence among populations This approach has been used to identify loci of ecological and evolutionary interest in a wide variety of taxa [2]. In order to better understand the adaptive processes that may have led to such ecological speciation, knowledge of adaptive diversification among disparate populations within species and the underlying genetic variation is of essential importance. This is because local adaptation within species may constitute the starting point of further diversification and can lead to speciation [6,7,8]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
