Topographically distinct adaptive landscapes for teeth, skeletons, and size explain the adaptive radiation of Carnivora (Mammalia)

Models of adaptive radiation were originally developed to explain the
early, rapid appearance of distinct modes of life within diversifying
clades. Phylogenetic tests of this hypothesis have yielded limited support
for temporally declining rates of phenotypic evolution across diverse
clades, but the concept of an adaptive landscape that links form to
fitness, while also crucial to these models, has received more limited
attention. Using methods that assess the temporal accumulation of
morphological variation and estimate the topography of the underlying
adaptive landscape, I found evidence of an early partitioning of
craniodental morphological variation in Carnivora (Mammalia) that occurs
on an adaptive landscape with multiple peaks, consistent with classic
ideas about adaptive radiation. Although strong support for this mode of
adaptive radiation is present in traits related to diet, its signal is not
present in body mass data or for traits related to locomotor behavior and
substrate use. These findings suggest that adaptive radiations may occur
along some axes of ecomorphological variation without leaving a signal in
others and that their dynamics are more complex than simple univariate
tests might suggest.