Ecological drivers of carnivoran body shape evolution

Morphological diversity is often attributed as adaptations to distinct
ecologies. Although biologists have long hypothesized that distinct
ecologies drive the evolution of body shape, these relationships are
rarely tested across macroevolutionary scales in mammals. Here, I tested
hypotheses that locomotor, hunting, and dietary ecologies influenced body
shape evolution in carnivorans, a morphologically and ecologically diverse
clade of mammals. I found that adaptive models with ecological trait
regimes were poor predictors of carnivoran body shape and the underlying
morphological components that contribute to body shape variation. Instead,
the best supported model exhibited clade-based evolutionary shifts,
indicating that the complexity and variation of body shape landscape
cannot be effectively captured by a priori ecological regimes. However,
ecological adaptations of body shapes cannot be ruled out as aquatic and
terrestrial carnivorans exhibited opposite allometric patterns of body
shape that may be driven by different gravitational constraints associated
with these different environments. Similar to body size, body shape is a
prominent feature of vertebrate morphology that may transcend one-to-one
mapping relationships between morphology and ecological traits, enabling
species with distinct body shapes to exploit similar resources and exhibit
similar ecologies. Together, these results demonstrate that the
multidimensionality of both body shape morphology and ecology makes it
difficult to disentangle the complex relationship between morphological
evolution, ecological diversity, and phylogeny across macroevolutionary
scales.