Multilocus molecular phylogenetic analysis of the montane Craugastor podiciferus species complex (Anura: Craugastoridae) in Isthmian Central America

Abstract

The Craugastor podiciferus complex is a group of phenotypically polymorphic direct-developing frogs that inhabit the Talamancan highlands of Costa Rica and Panama. The montane distribution of this group creates natural allopatry among members and offers an excellent opportunity to explore geographic models of speciation. Using a multilocus approach, we obtained data from one nuclear (c-myc) and three mitochondrial (12S, 16S, and COI) gene regions from 40 individuals within the C. podiciferus complex. Molecular phylogenetic analyses revealed a basal split that placed samples from western Panama as sister to Costa Rican (CR) samples, corroborating a previous suggestion that the former lineage may represent an undescribed species. Within the CR clades we found six distinct haplogroups whose distributions largely corresponded to geographic features and included instances of sympatry. Divergence estimates were used to develop a preliminary evolutionary timeframe for the diversification of the C. podiciferus complex. Based on collective evidence, we hypothesize that movement of the CR haplogroups has occurred between currently isolated areas of suitable habitat via second order climatic fluctuations during the Pleistocene. The levels of genetic differentiation within the C. podiciferus complex are remarkable given the relatively small geographic area (ca. 8000 km(2)) of occurrence. This diversity emphasizes the need for further study and taxonomic revision to aid in conservation planning for this complex which, like many amphibians, has experienced recent population declines.