Friday, April 19, 2013

Treeboa Ecomorphology


Neotropical treeboas (Corallus) form a monophyletic group of nine species distributed from south-eastern Guatemala to southeastern Brazil They occur on continental and oceanic islands and at elevations between sea level and about 1000 asl. All are moderately sized, with body lengths that are about 1.0–2.0 m, are relatively slender with laterally compressed bodies, thin necks, and large heads. They also have long, recurved teeth on the anterior portions of the maxilla and mandibles. As the common name suggests, they are arboreal and occur in forested habitats ranging from arid Acacia scrub
to primary rainforest, in mangrove swamps, fruit orchards, along gallery forests and riparian zones in Brazilian cerrado and caatinga, as well as urban and suburban situations where they will sometimes seek shelter in human dwellings. Prey is encountered during the night via active and ambush foraging, with some species employing both strategies.

Treeboa diets are largely comprised of lizards, birds, marsupials, rodents, and/or bats; prey is killed by constriction and, like all snakes, they are gape-limited. Several species undergo ontogenetic shifts in diet (e.g. lizards to rodents), some feed on birds and mammals, and others are stenophagic for mammals as adults.

In a forthcoming paper, Henderson et al. (2013) conducted the first study of morphology and diet that considers all nine treeboa species. Using adult specimens from museum collections, they examined several morphometric and meristic variables and their possible relationship to Corallus diets.

They found three basic morphologies within the genus: (1) a short, narrow head and a slender body (C. cookii, C. grenadensis, C. hortulanus, and C. ruschenbergerii), useful for exploiting a wide variety of prey (2) a relatively stout body with a long, wide head (C. batesii, C. caninus, and C. cropanii) associated with feeding on large mammals; and (3) an intermediate morphology, found in C. annulatus and C. blombergii, which may be indicative of endotherm generalists. These morphological and dietary patterns exhibit a strong degree of congruence with a recent molecular phylogeny of Corallus and highlight a heretofore unexamined ecological diversification within Corallus.


Citation
Henderson, R. W., M. J. Pauers, and T. J. Colston. 2013. On the congruence of morphology, trophic ecology, and phylogeny in Neotropical treeboas (Squamata: Boidae: Corallus). Biological Journal of the Linnean Society.

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