Meeting Abstract

28.9  Jan. 5  Things Fall Apart HART, M.W.**; SUNDAY, J.; Simon Fraser Univ.; Simon Fraser Univ. mike_hart@sfu.ca

Phylogeographic studies of marine (and other) animals frequently report within-species genetic variation that is consistent with cryptic species diversity or hybridization. We reviewed a number of such studies with an eye toward developing a quantitative and objective rule-of-thumb for identifying candidate cryptic species (or hybrids). The method uses between-species application of parsimony network (or minimum spanning tree) methods developed for within-species phylogeography. A survey of recent marine phylogeographic studies shows that alignments of DNA sequences typically fall apart into a separate subnetwork for each Linnean species, with low statistical confidence (< the 95% connection limit) in the connections between sequences from different species. In contrast, DNA sequences from single species � even those with broad ranges, complex biogeographic histories, or signatures of selection on the genetic markers � typically produce single haplotype networks. In other cases, sequences from single Linnean species fall apart into multiple subnetworks that have been interpreted as evidence of cryptic species diversity or introgression. The result suggests that such network analyses (as a supplement to other methods of species identification) can provide an objective benchmark for flagging cryptic species and hybrids. We illustrate some applications and limits of this method relative to recent speciation events and new (sometimes controversial) efforts to document the diversity of life through mitochondrial DNA barcoding.