The Biogeography of the Lizards of the Seychelles Islands

Abstract

The distributions of the eighteen species of lizards found in the Seychelles are given so far as they are known. The indigenous lizards of the granitic islands are endemic, at least at the specific level, and generally exhibit racial differentiation between island populations. The species-area relationship for the granitic islands is shallow, and there is little evidence for species turnover as predicted by the equilibrium theory of island biogeography. Low immigration rates arising from the isolation of the granitic Seychelles, together with low extinction rates due to climatic stability and high population densities may be responsible for this. The saurian faunas of the coralline islands are impoverished, with species not distinct from Madagascan and pantropical species. It is suggested that this has resulted from a recent sea-level stand higher than the present, which submerged the very low lying islands. Low rates of species immigration have not allowed the islands to attain a species equilibrium. This is supported by the presence of unfilled niches and the absence of a significant species-area relationship. The equilibrium model of island biogeography is of little relevance to the distribution of the Seychelles lizard fauna.