RICE, Amber M.; University of North Carolina, Chapel Hill: A Phylogeographic Investigation of Character Divergence
Closely related species often express different phenotypes in sympatry, but not in allopatry. Two spadefoot toad species (Spea bombifrons, S. multiplicata) exhibit this pattern of character divergence in tadpole morph production. Earlier studies on these species link resource competition in sympatry to divergence in morph production. Yet, it remains unclear whether such divergence resulted from selection in sympatry to reduce resource competition (i.e., character displacement), or whether it was a carryover of differences that arose in allopatry as lineages of each species adapted to different environmental conditions. I used a phylogeographic approach to distinguish between these possibilities. Using standard techniques, I sequenced a portion of the S. multiplicata mitochondrial genome. Each population was characterized by haplotypes present and species composition. Correlations among the haplotype lineages present in the different populations indicated which of the above hypotheses is the more likely explanation for character divergence in this system. Results are presented here.