Parallel evolution of toepads in rock-dwelling lineages of a terrestrial gecko (Gekkota: Gekkonidae: Heteronotia binoei)

Riedel, Jendrian, Zozaya, Stephen M., Hoskin, Conrad J., and Schwarzkopf, Lin (2021) Parallel evolution of toepads in rock-dwelling lineages of a terrestrial gecko (Gekkota: Gekkonidae: Heteronotia binoei). Zoological Journal of the Linnean Society, 193 (2). pp. 636-654.

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Abstract

Selection for effective locomotion can lead to specialized morphological structures. Adhesive toepads, which have arisen independently in different lizard clades, facilitate the use of vertical and inverted substrates. Their evolution is poorly understood because functionally intermediate morphological configurations between padless and pad-bearing forms are rare. To shed light on toepad evolution, we assessed the subdigital morphology of phylogenetically distinct lineages of the Bynoe's gecko species complex (Heteronotia binoei). Most populations of H. binoei are terrestrial, but two relatively distantly related saxicoline (rock-dwelling) lineages have enlarged terminal subdigital scales resembling toepads. We reconstructed the ancestral terminal subdigital scale size of nine lineages of H. binoei in eastern Australia, including these two saxicoline lineages. Additionally, we compared the subdigital microstructures of four lineages: the two saxicoline lineages and their respective terrestrial sister-lineages. Surprisingly, all four lineages had fully developed setae, but the setae of the two saxicoline lineages were significantly longer, branched more often and were more widely spaced than the terrestrial sister-lineages. We conclude that the saxicoline lineages represent examples of parallel evolution of enlarged adhesive structures in response to vertical substrate use, and their morphology represents a useful model as an intermediate state in toepad evolution.

Item ID: 70048
Item Type: Article (Research - C1)
ISSN: 1096-3642
Keywords: adaptation, adhesive system, micro-ornamentation, scanning electron microscopy (SEM), setae, species complex
Copyright Information: © 2021 The Linnean Society of London, Zoological Journal of the Linnean Society, 2021,
Date Deposited: 14 Feb 2022 01:48
FoR Codes: 31 BIOLOGICAL SCIENCES > 3103 Ecology > 310308 Terrestrial ecology @ 50%
31 BIOLOGICAL SCIENCES > 3104 Evolutionary biology > 310403 Biological adaptation @ 50%
SEO Codes: 28 EXPANDING KNOWLEDGE > 2801 Expanding knowledge > 280102 Expanding knowledge in the biological sciences @ 100%
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