Data from: Adaptation and constraint in the evolution of the mammalian backbone

Background: The axial skeleton consists of repeating units (vertebrae)
that are integrated through their development and evolution. Unlike most
tetrapods, vertebrae in the mammalian trunk are subdivided into distinct
thoracic and lumbar modules, resulting in a system that is constrained in
terms of count but highly variable in morphology. This study asks how
thoracolumbar regionalization has impacted adaptation and evolvability
across mammals. Using geometric morphometrics, we examine evolutionary
patterns in five vertebral positions from diverse mammal species
encompassing a broad range of locomotor ecologies. We quantitatively
compare the effects of phylogenetic and allometric constraints, and
ecological adaptation between regions, and examine their impact on
evolvability (disparity and evolutionary rate) of serially-homologous
vertebrae. Results: Although phylogenetic signal and allometry are evident
throughout the trunk, the effect of locomotor ecology is partitioned
between vertebral positions. Lumbar vertebral shape correlates most
strongly with ecology, differentiating taxa based on their use of
asymmetric gaits. Similarly, disparity and evolutionary rates are also
elevated posteriorly, indicating a link between the lumbar region,
locomotor adaptation, and evolvability. Conclusion: Vertebral
regionalization in mammals has facilitated rapid evolution of the
posterior trunk in response to selection for locomotion and static body
support.