Abstract
Many attributes of species may be linked to contemporary extinction risk, though some such traits remain untested despite suggestions that they may be important. Here, I test whether a trait associated with higher background extinction rates, chemical antipredator defence, is also associated with current extinction risk, using amphibians as a model system—a group facing global population declines. I find that chemically defended species are approximately 60% more likely to be threatened than species without chemical defence, although the severity of the contemporary extinction risk may not relate to chemical defence. The results confirm that background and contemporary extinction rates can be predicted from the same traits, at least in certain cases. This suggests that associations between extinction risk and phenotypic traits can be temporally stable over long periods. The results also provide novel insights into the relevance of antipredator defences for species subject to conservation concerns.
Highlights
In relation to efforts in biological conservation, there is a growing expectation that decisions about allocation of limited resources have a firm evidence base underlying them [1,2]
Contemporary amphibian species which possess chemical defences were 60% more likely to be threatened than species lacking such defences, according to my phylogenetic logistic regression model (β = 0.596, s.e. = 0.196, z = 3.045, p = 0.002; figure 1)
The results generally support the hypothesis that chemical defence is linked to contemporary extinction risk and tentatively support the directional hypothesis that the evolution of chemical defence causes an increased propensity to become threatened
Summary
In relation to efforts in biological conservation, there is a growing expectation that decisions about allocation of limited resources (such as finances and personnel) have a firm evidence base underlying them [1,2]. Such decisions are aimed to benefit those species deemed to be at higher risk of extinction, as often determined by the International Union for Conservation of Nature’s (IUCN) Red List categories [3].
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