BackgroundThe 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.ResultsAlthough 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.ConclusionVertebral regionalization in mammals has facilitated rapid evolution of the posterior trunk in response to selection for locomotion and static body support.Electronic supplementary materialThe online version of this article (10.1186/s12862-018-1282-2) contains supplementary material, which is available to authorized users.

The role played by coenzyme Q (CoQ) in the succinic tetrazolium reductase reaction was investigated. Fresh cryostat sections of normal rat tissues were extracted with acetone to remove CoQ from the tissue sections and the acetone-extracted sections were reconstituted with CoQ-lecithin complexes. The incubation film method for tetrazolium reductases was used as a test system, using succinate as a substrate. Sections from which CoQ had been selectively extracted did not reduce the tetrazolium to its formazan, whereas those acetone-extracted sections that were treated with CoQ-lecithin complexes or with the electron carrier phenazine methosulfate reacted positively. It was concluded that the succinic tetrazolium reductase reaction requires intermediate electron carriers, mainly CoQ. It follows that nitro blue tetrazolium cannot accept electrons directly from the flavins. Therefore, the tetrazolium reductase reaction depends not only on the amount of succinic dehydrogenase and flavins but also on the amount of CoQ in the tissue.

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Linking animal movement to landscape features is key to understanding the factors that determine the spatial and temporal distribution of wide-ranging species, especially those organisms that depend on access to resources that are temporally and spatially variable (Fryxell

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