Historical biogeography of Jamaica: evidence from cave invertebrates

Abstract

The Jamaican fauna of obligately subterranean invertebrates contains 25 species of terrestrial troglobitic onychophorans, arachnids, isopods, and hexapods and 16 species of freshwater - brackish water stygobites, mostly crustaceans. Cladistic analyses of the faunas are not available. In place of this, general track analysis of the cave-restricted terrestrial faunas suggests closest relationships with Jamaican forest faunas, followed by other West Indian forest or cave faunas, and lastly Central American forest faunas. Over-water dispersal best accounts for the presence of the terrestrial epigean ancestors of the fauna in Jamaica, and they must have arrived after Jamaica became emergent in the early Miocene (about 20 Ma). The terrestrial cave fauna then descended from the epigean ancestors. In contrast, the aquatic fauna invaded from the sea, but also after the Miocene emergence. There is no evidence for a macro-vicariance origin of the cave-evolved fauna from one existing in cave environments at the time when Jamaica separated from proto-Middle America. The troglobites probably arose on Jamaica through habitat shift or Pleistocene climatic change (both micro-vicariance mechanisms). Seven terrestrial and three aquatic species seem to be phylogenetic relicts. These relicts also have a stronger relationship to other Antillean islands than to Central America. This fauna shows no evidence of a South American origin. There is a very significant species-area linear regression for Greater Antillean stygobites but not for troglobites (probably because Hispaniola is not sufficiently studied).