Repeated Origin and Loss of Adhesive Toepads in Geckos

Abstract

Geckos are well known for their extraordinary clinging abilities and many species easily scale vertical or even inverted surfaces. This ability is enabled by a complex digital adhesive mechanism (adhesive toepads) that employs van der Waals based adhesion, augmented by frictional forces. Numerous morphological traits and behaviors have evolved to facilitate deployment of the adhesive mechanism, maximize adhesive force and enable release from the substrate. The complex digital morphologies that result allow geckos to interact with their environment in a novel fashion quite differently from most other lizards. Details of toepad morphology suggest multiple gains and losses of the adhesive mechanism, but lack of a comprehensive phylogeny has hindered efforts to determine how frequently adhesive toepads have been gained and lost. Here we present a multigene phylogeny of geckos, including 107 of 118 recognized genera, and determine that adhesive toepads have been gained and lost multiple times, and remarkably, with approximately equal frequency. The most likely hypothesis suggests that adhesive toepads evolved 11 times and were lost nine times. The overall external morphology of the toepad is strikingly similar in many lineages in which it is independently derived, but lineage-specific differences are evident, particularly regarding internal anatomy, with unique morphological patterns defining each independent derivation.

Combining phylogenomic and supermatrix approaches, and a time-calibrated phylogeny for squamate reptiles (lizards and snakes) based on 52 genes and 4162 species

“…Gamble et al, 2012) in dividing the group into two clades: one including Carphodactylidae, Diplodactylidae, and Pygopodidae, and the other containing Eublepharidae, Gekkonidae, Sphaerodactylidae, and Phyllodactylidae. In the former clade, the relationships are similar to those of Pyron et al (2013) in placing carphodactylids with pygopodids (with weak support in both studies), whereas placed diplodactylids with pygopodids with strong support (bs = 90%).…”

Effects of surface wettability on gecko adhesion underwater

“…However, there are more than 1400 species of geckos in the world and different species possess different natural habitats and living conditions [12]. Geckos in tropical rainforests may usually encounter or live on wet surfaces.…”

Introgression and repeated co-option facilitated the recurrent emergence of C4photosynthesis among close relatives

“…al. 2012), particularly when some character states affect the rates of speciation and/or extinction, when rates of transitions are high and asymmetrical, or variable among clades and through time (Maddison 2006; Goldberg and Igic 2008; Beaulieu et al. 2013; Igic and Busch 2013; King and Lee 2015).…”