UC Berkeley

Aim: Phylogeographical structure in the black salamander (Aneides flavipunctatus) was inferred using two independent genetic datasets. Concordance between the datasets was sought in order to evaluate earlier suggestions of species-level breaks and evidence of vicariance and long-term isolation within the complex. We hypothesized that major phylogeographical breaks would either correspond to current tectonic plate boundaries or to historical geological processes. Location: North-western California and southern Oregon (USA). Methods: Three mitochondrial DNA (mtDNA) genes were sequenced for 240 black salamanders from 136 localities, and up to 13 nuclear DNA loci were sequenced for 145 black salamanders representing 93 localities. Phylogenetic analysis of our mitochondrial dataset was performed to recover major lineages, while spatial clustering analysis of our nuclear dataset was utilized to identify points of concordance with our mtDNA phylogeny. Levels of gene flow were estimated for all contact zones. Results: Our mitochondrial phylogeny recovered four major lineages. Cluster analysis of our nuclear dataset is consistent with a four-population scheme, with the boundaries matching those of the mtDNA lineages. Gene flow across a contact zone in southern Humboldt between two of the populational units is extremely limited (2Nm < 1). In what is identified as the Central Core population, two distinctive subpopulations were delineated based on nuclear data, but mitochondrial data are discordant. Main conclusions: The Aneides flavipunctatus complex comprises at least four species-level units. Two of the boundaries between these units are associated with current tectonic plate boundaries. The contact zone between our Northwest and Central Core populations lies adjacent to the Mendocino Triple Junction (MTJ), where the Humboldt and North American plates meet, while the area separating the Santa Cruz and Central Core populations corresponds to the boundary between the Pacific and Humboldt tectonic plates. The phylogeographical break within the Central Core population lies in a region in which uplift occurred that is associated with the historical position of the migrating MTJ.