Phylogenetic relationships of Neogene hamsters (Mammalia, Rodentia, Cricetinae) revealed under Bayesian inference and maximum parsimony

Abstract

There is an ongoing debate about the internal systematics of today’s group of hamsters (Cricetinae), following new insights that are gained based on molecular data. Regarding the closely related fossil cricetids, however, most studies deal with only a limited number of genera and statements about their possible relationships are rare. In this study, 41 fossil species from the Late Miocene to the Pliocene, belonging to seven extinct cricetine genera, Collimys, Rotundomys, Neocricetodon, Pseudocricetus, Cricetulodon, Apocricetus and Hattomys are analysed in a phylogenetic framework using traditional maximum parsimony and Bayesian inference approaches. Following thorough model testing, a relaxed-clock Bayesian inference analysis is performed under tip-dating to estimate divergence times simultaneously. Furthermore, so-called ‘rogue’ taxa are identified and excluded from the final trees to improve the informative value of the shown relationships. Based on these resulting trees, the fit of the topologies to the stratigraphy is assessed and the ancestral states of the characters are reconstructed under a parsimonious approach and stochastic character mapping. The overall topologies resulting from Bayesian and parsimonious approaches are largely congruent to each other and confirm the monophyly of most of the genera. Additionally, synapomorphies can be identified for each of these genera based on the ancestral state reconstructions. Only Cricetulodon turns out to be paraphyletic, while ‘Cricetulodon’ complicidens is a member of Neocricetodon. Lastly, this work makes a contribution to a debate that went on for decades, as the genus Kowalskia can be confirmed as junior synonym of Neocricetodon.

Keywords

• Rodentia
• Cricetinae
• Bayesian inference
• Maximum parsimony
• Tip-dating
• Morphological clock