Murine locomotion and diversification

The relationship between organismal function and form is a cornerstone of
biology because functional diversity is key to generating and maintaining
ecological diversity. Morphological changes often occur in unison with
behavioral or ecological transitions, and this process may foster
diversification, but alternately could trap a species on an adaptive peak.
We estimated the most comprehensive phylogenetic hypothesis of Murinae, a
young (~15 My) and diverse (~700 species) clade of mammals. We then tested
for correlated evolution among four morphological traits with potential
links to locomotor modes (Arboreal, General, Terrestrial, and Amphibious),
then investigated the effects of locomotion on morphological and lineage
diversification. We found unique combinations of trait values for each
locomotor mode, including strong covariance between the tail and hind foot
lengths of specialized Arboreal and ecologically flexible General species.
Low diversification rates and long branch lengths suggest that specialized
lineages represent stable evolutionary “cul-de-sacs”. General species,
characterized by the classic “rat-like” body plan and broad locomotor
abilities, have narrow optimal trait values and slow phenotypic evolution,
but high lineage diversification rates. Our findings suggest that
versatile, generalist forms act as seeds of species diversity and
morphological specialization, which together build ecologically diverse
radiations.Muri