Record Details

Hedges, S Blair
The origin of West Indian amphibians and reptiles
Contributions to West Indian Herpetology. A Tribute to Albert Schwartz
1996
Book Section
Robert Powell and Robert W Henderson
95-128
Society for the Study of Amphibians and Reptiles
Ithaca, New York
Ctenosaura similis;Cyclura sp.;Iguana iguana;Iguana delicatissima
The known West Indian herpetofauna is comprised of 175 species of amphibians (99% endemic) and 457 species of reptiles (93% endemic). Information on distributions, relationships, and times of origin, with emphasis on estimates of divergence time from albumin immunological data, are analyzed in an attempt to understand the origin of the herpetofauna. Seventy-seven independent lineages of West Indian amphibians and reptiles are identified and nearly all (95%) originated in the New World. Of those lineages for which a source area within the New World can be determined, most (79%) show a South American origin, with smaller contributions from Central America (15%) and North America (6% ). One very old and diverse lineage, frogs of the genus Eleutherodactylus, originated by vicariance or dispersal in the late Cretaceous (70 mya). With one possible exception (the xantusiid lizard Cricosaura typica), all other lineages appear to have arrived by dispersal during the Cenozoic, and all but nine lineages in the last half of the Cenozoic (30-0 mya). Most West Indian lineages with multiple endemic species originated in the mid-Tertiary, whereas most lineages with a single endemic species arose in the late Tertiary. Quaternary dispersal is postulated to explain the origin of West Indian populations of mainland species. The probable explanation for the predominately South American origin of the West Indian herpetofauna is the nearly unidirectional (towards the west-northwest) water current patterns in the Caribbean: water reaching the Greater Antilles originates near the Lesser Antilles and South America. Wide variation in the times of origin for the West Indian lineages does not support the recent suggestion of a mid-Cenozoic landbridge between South America and the Greater Antilles. Dispersal, in most cases, is believed to have occurred by the discharge of organisms attached to flotsam from the mouths of major rivers on the continents and carried by currents to the West Indies. Proto-Antillean vicariance remains a geological possibility, but recent paleocoastline data suggest that a dry land connection betweenthe proto-Antilles and neighboring continents in the late Mesozoic may not have occurred. The widespread invoking of vicariance to explain nearly any distribution of West Indian organism without information on time of origin is seen as a popular trend but one that lacks support.