Invasive toxic amphibians: A bibliographic review

Abstract

Despite being globally in decline, a few amphibians are menacing biodiversity by their invasive character in some regions of the world. These invasive amphibians have chemical defenses and are known to take advantage of their toxicity to conquer new territories. Unfortunately, their diversity are concealed by one species particularly studied: Rhinella marina. With the aim of counterbalancing this issue, this work, focusing the invasive toxic amphibians, has been conducted. A dataset regrouping invasive toxic amphibians has been compiled using articles and others literature mentioning on one hand the invasiveness and on the other predator poisoning or the existence of toxic compounds. The toxins used as well as their origins have been discussed alongside with the impacts on native fauna, their adaptation, the invaders' taxonomic diversity and the benefits of toxicity. This taxonomic diversity is reflected in the large number of families (n = 10) containing at least one invasive and toxic species in the two major amphibian orders: Anura and Caudata. The toxin analysis revealed a wide range of toxic substances as well as some similarities between different families using the same molecules such as tetrodotoxin, a potent neurotoxin. The diversity of toxins goes hand in hand with the multiple effects possible in predators, ranging from a repellent taste to death, thus altering the feeding habits of predators. Consequently, toxicity turns out to be a major asset for invasive amphibians: it causes the decline of potential native predators and therefore in return promotes the proliferation of invasives. In conclusion, this dissertation provides a broad approach to invasive and toxic amphibians, bringing together a large amount of information for future research.