Meeting Abstract

28.1  Monday, Jan. 5  Vicariance or pseudocongruence? Evidence from a multi-species break in the northeastern Pacific MCGOVERN, TM*; KEEVER, CC; HART, MW; SASKI, CA; COX, LN; EMME, SA; HOFFMAN, JM; MARKO, PB; Clemson Univ.; Simon Fraser Univ.; Simon Fraser Univ.; Clemson Univ.; Clemson Univ.; Clemson Univ.; Clemson Univ.; Clemson Univ. tmcgove@clemson.edu

Comparative phylogeography often reveals the existence of shared phylogeographic breaks across multiple, co-distributed species, a pattern consistent with a hypothesis of vicariance, in which a single event simultaneously disrupted the geographic ranges of many species. The hypothesis of vicariance, however, not only requires geographic concordance, but also temporal congruence with respect to the disruption of gene flow. Recently, several multi-species breaks have been shown to represent cases of pseudo-congruence, in which a geographically concordant break resulted at different times in different taxa. Pinpointing the timing of divergence therefore not only contributes to our understanding of the historical processes shaping spatial patterns of genetic variation, but also has great significance to community ecology given the potential for testing hypotheses about the geographic responses of groups of interacting species to environmental change. We have employed Bayesian/Markov chain Monte Carlo methods to compare mtDNA-based estimates of divergence time in multiple species in an area of the northeastern Pacific in which a phlyogeographic break has previously been documented. For two of these species a benthic brooder and a free-spawner with planktonic larvae – we refine our estimates of divergence time by adding six anonymous nuclear loci. We use these analyses to discuss broader issues of phylogeographic congruence as well as implications for the impact of life histories and species interactions on responses to environmental change.