Rarity in snakes: a case study with vipers from the new world

Abstract

In order to improve conservation it is necessary to understand the factors that influences species' vulnerability. For example, the knowledge of the geographic distribution of species is a prerequisite for conservation priorities. The researcher Deborah Rabinowitz proposed, around 1980, that a species rarity could be described considering three aspects: (1) its geographic distribution, (2) habitat specificity and (3) population density. A restrict distribution associated with high habitat specificity and low densities, would render a species extremely vulnerable to extinction. Recent studies indicate that rarity patterns are positively correlated to extinction risk estimated through traditional methods. Therefore, the knowledge of the rarity pattern of a group may be an effective way to detect species that are more vulnerable to extinction, resulting in a better conservation strategy. The objectives of this study are: (I) to explore rarity patterns in a monophyletic group of snakes, the New World vipers; (II) to compare these results with the risk assessments estimated by traditional methods (IUCN); and (III) identify geographic patterns in the distribution of rare species.(AU)