Phylogenetic relationships of dasyuromorphian marsupials revisited

Abstract

We reassessed the phylogenetic relationships of dasyuromorphians using a large molecular database comprising previously published and new sequences for both nuclear (nDNA) and mitochondrial (mtDNA) genes from the numbat (Myrmecobius fasciatus), most living species of Dasyuridae, and the recently extinct marsupial wolf, Thylacinus cynocephalus. Our molecular tree suggests that Thylacinidae is sister to Myrmecobiidae + Dasyuridae. We show robust support for the dasyurid intrafamilial classification proposed by Krajewski & Westerman as well as for placement of most dasyurid genera, which suggests substantial homoplasy amongst craniodental characters presently used to generate morphology-based taxonomies. Molecular dating with relaxed molecular clocks suggests that dasyuromorphian cladogenesis began in the Eocene, and that all three dasyuromorphian families originated prior to the end of this epoch. Radiation within Thylacinidae and Dasyuridae had occurred by the middle to late Oligocene, consistent with recognition of primitive thylacinids (e.g. Badjcinus turnbulli) in the later Oligocene and of putative dasyurids (e.g. Barinya wangala) by the early Miocene. We propose that all four extant dasyurid tribes were in existence by the early Miocene and that most modern dasyurid genera/species were established before the later Miocene. This is in marked contrast to the popularly accepted advocation of their origins in the latest Miocene-early Pliocene.

A new family of bizarre durophagous carnivorous marsupials from Miocene deposits in the Riversleigh World Heritage Area, northwestern Queensland

“…Until recently, all known dasyuromorphians have been comfortably accommodated into one of three families: Dasyuridae, Thylacinidae and Myrmecobiidae, with the interrelationships of these clades the subject of long-standing controversy123456. In the main, this reflects modern dasyuromorphian biodiversity because relatively little of the fossil record of the order is known, with none at all for myrmecobiids.…”

Bandicoot fossils and DNA elucidate lineage antiquity amongst xeric-adapted Australasian marsupials

“…S7) that determined the best-supported position of fossils relative to the living species topology; and (2) compute a combined (non-weighted) total evidence analysis that examined effects of morphological data on molecular nodes. Laboratory procedures, DNA sequence derivation/alignment, and model testing of separate gene/codon regions were described in Westerman et al 168.…”

Marsupials don't adjust their thermal energetics for life in an alpine environment

“…ANCOVA was used to compare the thermolability of the 4 antechinus species, calculated as the slope of T b against T a from T a = 10–30°C. For all comparisons between species, physiological variables were corrected for body mass effects using allometric scaling exponents for marsupials (0.533 for T b , 0.737 for BMR, 0.564 for C wet and C dry and 0.736 for EWL), calculated from the data of Withers et al, 23 Warnecke et al 42 and Pusey et al 43 …”

“…We compared standard T b , BMR, standard EWL and standard C wet (measured at T a = 30°C) of our 4 species of antechinus to the 95% prediction limits 44 for the log-transformed allometric relationships for other marsupials (using the dataset of Warnecke et al 42 with additional data from Withers et al, 23 Withers and Cooper, 37 Pusey et al 43 and Tomlinson et al, 45 using both conventional least-squares regression and phylogenetically-informed regression, after rendering the data independent of phylogeny using autoregression 46,47 and the phylogenetic trees of Bininda-Emonds et al 48 and Westerman et al 49 …”