How species respond to multiple extinction threats.

Abstract

It is well established that different species vary in their vulnerability to extinction risk and that species biology can underpin much of this variation. By contrast, very little is known about how the same species responds to different threat processes. The purpose of this paper is therefore twofold: to examine the extent to which a species' vulnerability to different types of threat might covary and to explore the biological traits that are associated with threat-specific responses. We use an objective and quantitative measure of local extinction risk to show that vulnerability to local population decline in primates varies substantially among species and between threat types. Our results show that a species' response to one threat type does not predict its response to others. Multivariate analyses also suggest that different mechanisms of decline are associated with each type of threat, since different biological traits are correlated with each threat-specific response. Primate species at risk from forestry tend to exhibit low ecological flexibility, while those species vulnerable to agriculture tend to live in the canopy and eat low-fruit diets; in further contrast, primates at risk from hunting tend to exhibit large body size. Our analyses therefore indicate that a species' vulnerability to local extinction can be highly variable and is likely to depend on both threat type and biology.

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