TY - JOUR

T1 - A farewell to arms and legs

T2 - a review of limb reduction in squamates

AU - Camaiti, Marco

AU - Evans, Alistair R.

AU - Hipsley, Christy A.

AU - Chapple, David G.

N1 - Funding Information: This study was supported by grants from the Holsworth Wildlife Research Endowment – Equity Trustees Charitable Foundation & the Ecological Society of Australia, and the Monash‐Museums Victoria Robert Blackwood scholarship (to M.C.), an Australian Research Council Linkage Project grant (LP170100012; to D.G.C. and A.R.E.) and Discovery Early Career Researcher Award (DECRA: DE180100629, to C.A.H.). Funding Information: This study was supported by grants from the Holsworth Wildlife Research Endowment ? Equity Trustees Charitable Foundation & the Ecological Society of Australia, and the Monash-Museums Victoria Robert Blackwood scholarship (to M.C.), an Australian Research Council Linkage Project grant (LP170100012; to D.G.C. and A.R.E.) and Discovery Early Career Researcher Award (DECRA: DE180100629, to C.A.H.). Publisher Copyright: © 2021 Cambridge Philosophical Society

PY - 2021

Y1 - 2021

N2 - Elongated snake-like bodies associated with limb reduction have evolved multiple times throughout vertebrate history. Limb-reduced squamates (lizards and snakes) account for the vast majority of these morphological transformations, and thus have great potential for revealing macroevolutionary transitions and modes of body-shape transformation. Here we present a comprehensive review on limb reduction, in which we examine and discuss research on these dramatic morphological transitions. Historically, there have been several approaches to the study of squamate limb reduction: (i) definitions of general anatomical principles of snake-like body shapes, expressed as varying relationships between body parts and morphometric measurements; (ii) framing of limb reduction from an evolutionary perspective using morphological comparisons; (iii) defining developmental mechanisms involved in the ontogeny of limb-reduced forms, and their genetic basis; (iv) reconstructions of the evolutionary history of limb-reduced lineages using phylogenetic comparative methods; (v) studies of functional and biomechanical aspects of limb-reduced body shapes; and (vi) studies of ecological and biogeographical correlates of limb reduction. For each of these approaches, we highlight their importance in advancing our understanding, as well as their weaknesses and limitations. Lastly, we provide suggestions to stimulate further studies, in which we underscore the necessity of widening the scope of analyses, and of bringing together different perspectives in order to understand better these morphological transitions and their evolution. In particular, we emphasise the importance of investigating and comparing the internal morphology of limb-reduced lizards in contrast to external morphology, which will be the first step in gaining a deeper insight into body-shape variation.

AB - Elongated snake-like bodies associated with limb reduction have evolved multiple times throughout vertebrate history. Limb-reduced squamates (lizards and snakes) account for the vast majority of these morphological transformations, and thus have great potential for revealing macroevolutionary transitions and modes of body-shape transformation. Here we present a comprehensive review on limb reduction, in which we examine and discuss research on these dramatic morphological transitions. Historically, there have been several approaches to the study of squamate limb reduction: (i) definitions of general anatomical principles of snake-like body shapes, expressed as varying relationships between body parts and morphometric measurements; (ii) framing of limb reduction from an evolutionary perspective using morphological comparisons; (iii) defining developmental mechanisms involved in the ontogeny of limb-reduced forms, and their genetic basis; (iv) reconstructions of the evolutionary history of limb-reduced lineages using phylogenetic comparative methods; (v) studies of functional and biomechanical aspects of limb-reduced body shapes; and (vi) studies of ecological and biogeographical correlates of limb reduction. For each of these approaches, we highlight their importance in advancing our understanding, as well as their weaknesses and limitations. Lastly, we provide suggestions to stimulate further studies, in which we underscore the necessity of widening the scope of analyses, and of bringing together different perspectives in order to understand better these morphological transitions and their evolution. In particular, we emphasise the importance of investigating and comparing the internal morphology of limb-reduced lizards in contrast to external morphology, which will be the first step in gaining a deeper insight into body-shape variation.

KW - body elongation

KW - internal morphology

KW - limb reduction

KW - limb-reduced squamates

KW - macroevolution

KW - morphological evolution

KW - snake-like lizards

U2 - 10.1111/brv.12690

DO - 10.1111/brv.12690

M3 - Journal article

C2 - 33538028

AN - SCOPUS:85100345418

VL - 96

SP - 1035

EP - 1050

JO - Biological Reviews

JF - Biological Reviews

SN - 1464-7931

IS - 3

ER -