Molecular phylogeny of an endemic radiation of Cuban toads (Bufonidae: Peltophryne) based on mitochondrial and nuclear genes

Aim In this study we present a molecular phylogenetic and phylogeographical analysis of Peltophryne (Anura: Bufonidae), an endemic genus of Antillean toads, to investigate the spatial and temporal origins of the genus, with particular focus on the eight Cuban species. Location Greater Antilles, with extensive sampling of the Cuban archipelago. Methods We obtained DNA sequence data from two mitochondrial genes, cytochrome c oxidase subunit I (COI) and ribosomal RNA (16S), for 124 toads representing all eight Cuban species, and combined this with published data from Hispaniola (one of three species) and Puerto Rico (one of one species) to establish a molecular phylogeny for Peltophryne. In addition, we explored the phylogeographical structure of widespread Cuban species. For a subset of 42 toads we also obtained DNA sequence data from two nuclear genes, recombination activator-1 (RAG-1) and chemokine receptor 4 (CXCR-4). We combined our molecular data with published DNA sequences from a global sample of bufonid toads to place the spatial and temporal origins of Peltophryne in the Caribbean within a fuller geographical and phylogenetic context. Results All phylogenetic analyses supported the monophyly of West Indian toads. The ancestor of Peltophyrne diverged from its mainland source around the Eocene-Oligocene boundary, with a subsequent radiation across the Caribbean islands taking place during the Miocene. Cuban species are monophyletic with a basal split in the early-middle Miocene that separates extant small-bodied from large-bodied species. Extensive mitochondrial DNA (mtDNA) sampling within widespread Cuban species revealed contrasting phylogeographical patterns. Peltophryne taladai and P. empusa showed deeply divergent lineages, whereas no geographical structure was observed in the widespread P. peltocephala. Main conclusions Our timeline for Peltophryne diversification is consistent with a biogeographical model requiring no long-distance overwater dispersal. Although confidence intervals on divergence time estimates are wide, the stem age of Peltophyrne coincides with the hypothesized GAARlandia landspan or archipelago, which may have connected South America briefly with the Antilles. The ages of Peltophryne for Puerto Rico, Hispaniola and Cuba are consistent with a recently proposed vicariance scenario for the region. Our molecular results support the recognition of all eight species in Cuba, and provide evidence of possible cryptic species.