Evolution of habitat preference in 243 species of Bent-toed geckos (Genus Cyrtodactylus Gray, 1827) with a discussion of karst habitat conservation

Ancestral state reconstructions of nine different habitat preferences across a phylogeny composed of 76% of the gekkonid genus <i>Cyrtodactylus</i> recover a general habitat preference as being ancestral to all other habitat preferences. The data show that <i>Cyrtodactylus</i> composes an ecologically labile group of species and the frequency of transitioning from a general habitat preference to anything more specialized occurs nearly four times more often than the reverse. Species showing extreme morphological and/or ecological specializations appear to be evolutionary dead ends that do not give rise to species bearing other habitat preferences. Habitat preferences have not evolved randomly across the genus but are generally restricted to clades that tend to occur in specific geographic regions. The largest radiations in the genus occur in rocky habitats (granite and karst), indicating that the transition from a general habitat preference to a granite or karst-dwelling life style is ecologically uncomplicated. Two large, unrelated clades of karst-associated species are centered in northern Indochina and the largest clade of granite-associated species occurs on the Thai-Malay Peninsula. Smaller, independent radiations of clades bearing other habitat preferences occur throughout the tree across the broad distribution of the genus from South Asia to the Western Pacific. With the exception of a general habitat preference, the data show that karst-associated species outnumber all others (28% versus 0.4–10%, respectively) and the common reference to karstic regions as "imperiled arcs of biodiversity" is not only misleading but potentially dangerous. Karstic regions are not simply refugia harboring the remnants of local biodiversity but are foci of speciation that continue to generate the most speciose, independent, radiations across the genus. Unfortunately, karstic landscapes are some of the most imperiled and least protected habitats on the planet and these data continue to underscore the urgent need for their conservation.