Comparative evaluation of macroevolutionary regimes of Ruminantia and selected mammalian lineages.

Rossi, Mariana F; Mello, Beatriz; Schrago, Carlos G

Ruminant artiodactyls have often been used to investigate the interplay between the evolution of phenotypic traits, lineage diversification rates and palaeoecology. In this context, the episodic increases in the occurrence of ruminant fossils, followed by modifications in tooth morphology during the Cenozoic, are frequently associated with the expansion of C3 and C4 grasslands, which took place in the late Oligocene and late Miocene, respectively. However, no comparative studies exist, making it impossible to contrast the macroevolutionary regime of ruminants with those of other mammals. Here, we tested for the exclusivity and magnitude of changes in diversification rates during Ruminantia evolution when compared to other lineages of placental mammals. Ruminantia presented a consistent and significant signal for a single diversification rate shift in the late Oligocene, matching the expansion of C3 grasslands. However, shifts in diversification rate were also recovered for Rodentia, Chiroptera and Eulipotyphla for this same period, questioning the exclusive association between the evolution of Ruminantia and grassland expansion. Molecular phylogenies, therefore, do not support the model of two rounds of shifts in diversification rate in Ruminantia (matching the age of expansion of C3 and C4 grasslands), instead favouring a single burst. The exclusiveness of such a burst was not recovered, suggesting that other factors may have played a role in prompting the radiation of several mammalian lineages with heterogeneous biologies during the Oligocene.

COEVOLUTION; GRASSLANDS; MACROEVOLUTION; OLIGOCENE Epoch; MAMMALS

Biological Journal of the Linnean Society, 2018, Vol 123, Issue 4, p814

0024-4066

Academic Journal

10.1093/biolinnean/bly009