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Why chemically defended amphibians are more likely to face extinction: a phylogenetic comparative test of hypotheses. / RACHEL HAYNES
Swansea University Author: RACHEL HAYNES
Abstract
Chemical defence is an antipredator mechanism employed by many amphibians. Despite this, chemically defended amphibians have been shown to exhibit a 60% higher contemporary extinction risk than non-defended species, with a three-times higher background extinction rate. Using structural equation mode...
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Swansea
2026
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| Institution: | Swansea University |
| Degree level: | Master of Research |
| Degree name: | MRes |
| URI: | https://cronfa.swan.ac.uk/Record/cronfa71780 |
| Abstract: |
Chemical defence is an antipredator mechanism employed by many amphibians. Despite this, chemically defended amphibians have been shown to exhibit a 60% higher contemporary extinction risk than non-defended species, with a three-times higher background extinction rate. Using structural equation models (SEMs), this phylogenetic comparative study aimed to disentangle the indirect mechanisms explaining this seemingly counterintuitive link. Three hypotheses were tested: the marginal habitats hypothesis, the slow life history hypothesis and the energetics hypothesis. Using the IUCN Red List, the second Global Amphibian Assessment, AmphiBIO and the Global Amphibian Biodiversity Project, data on chemical defence, threat status and population trajectory were compiled for 855 amphibian species.Data on habitat use, life history and body size were obtained to serve as proxies for each hypothesis. The SEMs show that the benefits of chemical defence enable species to survive in a higher proportion of marginal habitats than non-defended species. However, the intrinsic instability of these habitats will ultimately put these species at higher risk of extinction.Therefore, the marginal habitats hypothesis provides a strong explanation for the indirect effect of chemical defence on extinction risk. There was weaker support for the slow life history hypothesis and no support for the energetics hypothesis. These results underscore the importance of considering an amphibians’ full ecological context when assessing extinction risk and allocating conservation resources. |
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| Keywords: |
comparative, phylogenetics, amphibian, extinction, conservation |
| College: |
Faculty of Science and Engineering |