DNA phylogeny of the marsupial wolf resolved

Area of Science:

• * Mammalian Systematics
• * Molecular Phylogenetics
• * Paleontology

Background:

• * The thylacine (Thylacinus cynocephalus), or marsupial wolf, is an extinct apex predator endemic to Australasia.
• * Its anatomical similarities to South American borhyaenids have led to debate regarding its evolutionary placement—convergent evolution versus common ancestry.
• * Previous studies using morphology and ancient DNA/protein analyses have yielded ambiguous results regarding thylacine affinities.

Purpose of the Study:

• * To definitively determine the phylogenetic position of the thylacine within marsupial systematics.
• * To resolve the long-standing debate on whether thylacine traits resulted from convergent evolution or shared ancestry.

Main Methods:

• * Sequencing of mitochondrial DNA (cytochrome b and 12S rRNA genes) and nuclear protamine gene from thylacine specimens.
• * Phylogenetic analysis incorporating sequences from the thylacine and representatives of other major marsupial orders.

Main Results:

• * Phylogenetic analyses of both mitochondrial and nuclear DNA sequences unambiguously place the thylacine within the order Dasyuromorphia.
• * The study suggests that familial lineages within Dasyuromorphia diverged in the late Oligocene or early Miocene.
• * Morphological similarities to borhyaenids are attributed to convergent adaptation to carnivory rather than close ancestry.

Conclusions:

• * The thylacine is confirmed as a member of Dasyuromorphia, resolving a century-old debate in mammalian systematics.
• * This finding clarifies the evolutionary history of Australasian marsupials and the nature of adaptive radiations in carnivory.