What drives phenotypic divergence in spinner dolphins?

Distribution of spinner dolphin ecotypes (adapted from Andrews et al. 2013, Fig. 1). Photo credits: Dwarf — M. T. Aquino; Gray’s — C. Vanderlip, NOAA Fisheries Permit #10137-06; Whitebelly — W. Perrin; Eastern, Tres Marias, Central American — M. Richlen.

The spinner dolphin (Stenella longirostris) species has six ecotypes that differ in morphology, habitat, and mating system.  But despite these differences, population genetic analyses have shown relatively little genetic divergence between most ecotypes at most genetic markers.  How is this possible?  There are several potential explanations, including an obscured genetic signal due to very large population sizes, relatively high levels of interbreeding between ecotypes, or assortative mating driven by sexual selection.  I’m collaborating with a large team of researchers to further explore the evolutionary mechanisms driving diversification in this species using thousands of genetic markers scattered across the genome.

To read more about this work, check out our publication:

Andrews KR, WF Perrin, M Oremusk, L Karczmarski, BW Bowen, JB Puritz, RJ Toonen. 2013. The evolving male: spinner dolphin (Stenella longirostris) ecotypes are divergent at Y chromosome but not mtDNA or autosomal markers. Molecular Ecology 22(9):2408-23.


Are Idaho ground squirrels locally adapted to habitat patches?


Northern Idaho ground squirrel. Photo credit: Amanda Goldberg

Northern Idaho ground squirrels and southern Idaho ground squirrels are threatened species that occur only in central Idaho, within just a fraction of their former range.  They persist in small populations in patches of meadows and rocky outcroppings within coniferous forests.  We’re using a landscape genomic approach to understand population connectivity and evaluate whether populations are locally adapted to the unique environmental conditions of each habitat patch.  This information will help us evaluate the vulnerability of each population to environmental change.