A timescale and phylogeny for "bandicoots" (Peramelemorphia: Marsupialia) based on sequences for five nuclear genes

Relationships among the living and recently extinct genera of bandicoots (Marsupialia: Peramelemorphia) have proven difficult to discern. Previous phylogenetic studies have used only morphology or mitochondrial DNA and have reported conflicting results in regards to their relationships. Most phylogenetic reconstructions recognize a basal split between the bilby Macrotis (Thylacomyidae) and the Peramelidae. The Peramelidae is composed of the Peramelinae (Isoodon and Perameles), Echymiperinae (Echymipera and Microperoryctes), and Peroryctinae (Peroryctes). Within Peramelidae, Echymipera and Microperoryctes usually group together to the exclusion of Peroryctes. This clade is sister to the Peramelinae. Placement of the recently extinct pig-footed bandicoot (Chaeropus: Chaeropodidae) has been ambiguous. We address the interrelationships and estimate times of divergence for the living bandicoot genera using a 6 kilobase concatenation consisting of protein-coding regions of five nuclear genes (ApoB, BRCA1, IRBP, Rag1, and vWF). We analyzed this concatenation using maximum parsimony, maximum likelihood, and Bayesian methods and estimated times of divergence using two Bayesian relaxed molecular clock methods. In all concatenated analyses, all nodes associated with the Peramelemorphia were robustly supported (bootstrap support percentages=100; posterior probabilities=1.00). Macrotis was recovered as basal to the remaining living bandicoots. Within the Peramelidae, Echymipera and Microperoryctes grouped to the exclusion of Peroryctes and this clade was sister to the Peramelinae. Only Rag1 amplified for Chaeropus; analyses based on this gene provide moderate support for an association of Chaeropus plus Peramelidae to the exclusion of Macrotis. Both relaxed clock Bayesian methods suggest that the living bandicoots are a relatively recent radiation originating sometime in the late Oligocene or early Miocene with subsequent radiations in the late Miocene to early Pliocene.