Abstract
Venoms are best known for their ability to incapacitate prey. In predatory groups, venom potency is predicted to reflect ecological and evolutionary drivers relating to diet. While venoms have been found to have prey-specific potencies, the role of diet breadth on venom potencies has yet to be tested at large macroecological scales. Here, using a comparative analysis of 100 snake species, we show that the evolution of prey-specific venom potencies is contingent on the breadth of a species’ diet. We find that while snake venom is more potent when tested on species closely related to natural prey items, we only find this prey-specific pattern in species with taxonomically narrow diets. While we find that the taxonomic diversity of a snakes’ diet mediates the prey specificity of its venom, the species richness of its diet was not found to affect these prey-specific potency patterns. This indicates that the physiological diversity of a species’ diet is an important driver of the evolution of generalist venom potencies. These findings suggest that the venoms of species with taxonomically diverse diets may be better suited to incapacitating novel prey species and hence play an important role for species within changing environments.
Highlights
Venoms have evolved through natural selection into complex mixtures, comprised of diverse assortments of toxic proteins, peptides, minerals and molecular components [1,2,3,4]
We find that diet breadth mediates the prey specificity of snake venom with species, with taxonomically narrow diets having prey-specific venom potencies, while species with taxonomically broad diets have venoms which display more generalist potency patterns
The venom of predators with specialist diets are predicted to show higher degrees of prey-specific potency in comparison to those with generalist diets [13]. Evidence for such mediating effects of diet diversity on prey specificity has been shown in cone snails (Conus sp.), where species with more diverse diets were found to have more complex venoms, potentially allowing them to target a broader range of prey species [18,28]
Summary
Venoms have evolved through natural selection into complex mixtures, comprised of diverse assortments of toxic proteins, peptides, minerals and molecular components [1,2,3,4]. The venom of predators with specialist diets are predicted to show higher degrees of prey-specific potency in comparison to those with generalist diets [13] Evidence for such mediating effects of diet diversity on prey specificity has been shown in cone snails (Conus sp.), where species with more diverse diets were found to have more complex venoms, potentially allowing them to target a broader range of prey species [18,28]. One approach to account for this confounding issue is to include a measure of the evolutionary distance between the natural prey species and the species on which a venom potency has been measured [14] This approach allows venom potency data measured on a wide range of animals to be used to test hypothesises relating to the functional evolution of venom within standard phylogenetic comparative frameworks [14].
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