Locomotion and palaeoclimate explain the re-evolution of quadrupedal body form in Brachymeles lizards |
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Authors: | Philip J Bergmann Gen Morinaga Elyse S Freitas Duncan J Irschick Günter P Wagner Cameron D Siler |
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Institution: | 1.Department of Biology, Clark University, 950 Main Street, Worcester, MA 01610, USA;2.Department of Biology and Sam Noble Oklahoma Museum of Natural History, University of Oklahoma, 2401 Chautauqua Ave., Norman, OK 73072, USA;3.Department of Biology, University of Massachusetts Amherst, Amherst, MA, USA;4.Department of Ecology and Evolutionary Biology, Yale University, New Haven, CT, USA |
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Abstract: | Evolutionary reversals, including re-evolution of lost structures, are commonly found in phylogenetic studies. However, we lack an understanding of how these reversals happen mechanistically. A snake-like body form has evolved many times in vertebrates, and occasionally a quadrupedal form has re-evolved, including in Brachymeles lizards. We use body form and locomotion data for species ranging from snake-like to quadrupedal to address how a quadrupedal form could re-evolve. We show that large, quadrupedal species are faster at burying and surface locomotion than snake-like species, indicating a lack of expected performance trade-off between these modes of locomotion. Species with limbs use them while burying, suggesting that limbs are useful for burying in wet, packed substrates. Palaeoclimatological data suggest that Brachymeles originally evolved a snake-like form under a drier climate probably with looser soil in which it was easier to dig. The quadrupedal clade evolved as the climate became humid, where limbs and large size facilitated fossorial locomotion in packed soils. |
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Keywords: | elongation lizard locomotion re-evolution |
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