@article {841566, title = {The role of isoforms in the evolution of cryptic coloration in Peromyscus mice}, journal = {Molecular Ecology}, volume = {26}, year = {2017}, pages = {245-258}, abstract = {

A central goal of evolutionary biology is to understand the molecular mechanisms underlying phenotypic adaptation. While the contribution of protein-coding and\ cis-regulatory mutations to adaptive traits have been well documented, additional sources of variation{\textemdash}such as the production of alternative RNA transcripts from a single gene, or isoforms{\textemdash}have been understudied. Here, we focus on the pigmentation gene\ Agouti, known to express multiple alternative transcripts, to investigate the role of isoform usage in the evolution of cryptic color phenotypes in deer mice (genus\ Peromyscus). We first characterize the\ Agouti\ isoforms expressed in the\ Peromyscus\ skin and find two novel isoforms not previously identified in\ Mus. Next, we show that a locally adapted light-colored population of\ P. maniculatus\ living on the Nebraska Sand Hills shows an up-regulation of a single\ Agouti\ isoform, termed 1C, compared to their ancestral dark-colored conspecifics. Using\ in vitro\ assays, we show that this preference for isoform 1C may be driven by isoform-specific differences in translation. In addition, using an admixed population of wild-caught mice, we find that variation in overall\ Agouti\ expression maps to a region near exon 1C, which also has patterns of nucleotide variation consistent with strong positive selection. Finally, we show that the independent evolution of cryptic light pigmentation in a different species,\ P. polionotus, has been driven by a preference for the same\ Agouti\ isoform. Together, these findings present an example of the role of alternative transcript processing in adaptation and demonstrate molecular convergence at the level of isoform regulation.

}, author = {Mallarino, R. and Linden, T. A. and Linnen, C. R. and Hoekstra, H. E.} }