Are there shared general patterns of specific diversity, abundance, and guild structure in snake communities of tropical forests of Madagascar and continental Africa?

A comparative study of snake community composition of 45 tropical forest pa tches, including both original and literature data, is presented. Twelve st udy areas are situated in Nigeria, one in Cameroon, and 30 in Madagascar. T wo forest sites from Panama were also used as outgroups. There was a remark able consistency among: sites in inter-regional comparisons in terms of mea n number of species observed x min. The highest similarities were between N igerian and Malagasy sites and between Cameroon and Nigerian sites, whereas similarities between all these African sites and Panama sites were lower. Altitude and linear distances among sites did not influence significantly t he snake species detection and abundance. Nigerian sites had comparatively higher numbers of semi-aquatic taxa than Malagasy sites. The terrestrial gu ild was the dominant one, and the arboreal guild was constituted by a remar kable diversity of species, in nearly all sites of both Nigeria and Madagas car. There was a very low diversity of syntopic fossorial species in both N igeria and Madagascar (in all 22 study plots, only 1 or 2 fossorial species were found). In Nigerian sites there was a general prevalence of primarily lacertophagous and mammalophagous species, but batracophagous and ornithop hagous species were also quite abundant. In the Malagasy sites lacertophago us species were significantly prevalent, followed by batracophagous species , whereas species with other dietary preferences (e.g., mammalophagous) wer e much under-represented. The abundance of species feeding: on invertebrate s and of generalist species was similar in the two geographic regions, wher eas piscivorous species were found only in the Nigerian sites. The scarcity of mammalophagous, piscivorous and ornithophagous species in Madagascar co uld be interpreted as a general biogeographic pattern in terms of food type availability (taking into account the scarcity of some types of prey in Ma lagasy forests and freshwater streams) as well as in terms of snake size di stributions. With regard to snake body size distributions in the various ex amined communities, it appeared that forest environments of both Nigeria an d Madagascar can house a similar snake community as for numbers of species < 2 m in length, but Nigerian environments can harbour numbers of giant and very large species (from 2 to 9 m in length) that cannot be hold in Malaga sy forests. The ecological patterns emerged in this comparative study are d iscussed in the light of current community ecology theory and biogeography.