Tadpoles of hybridising fire-bellied toads (B. bombina and B. variegata) differ in their susceptibility to predation

• Published in: PloS one Vol. 15; no. 12; p. e0231804
• Main Authors: Smolinsky, Radovan, Balaz, Vojtech, Nurnberger, Beate
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 07.12.2020; Public Library of Science (PLoS)
• Subjects: Adaptation; Adaptation, Physiological - physiology; Animal behavior; Animal reproduction; Animals; Anura - embryology; Anura - genetics; Anura - metabolism; Aquatic habitats; Behavior, Animal; Biology; Biology and Life Sciences; Bombina bombina; Divergence; Earth Sciences; Ecology and Environmental Sciences; Ecosystem; Escape Reaction - physiology; Fire-bellied toad; Gene flow; Gene Flow - genetics; Gene pool; Genetic aspects; Geography; Habitats; Hunting; Hybridization; Hybridization, Genetic; Juveniles; Laboratories; Laboratory experiments; Larva - genetics; Larva - metabolism; Larvae; Morphology; Natural history; Natural selection; New species; Phenotypes; Phylogeny; Physiological aspects; Predation; Predation (Biology); Predators; Predatory Behavior - physiology; Reproductive isolation; Selection, Genetic; Species Specificity; Swimming; Tadpoles; Taxa; Toads; Zoological research; Czech Republic
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0231804

The role of adaptive divergence in the formation of new species has been the subject of much recent debate. The most direct evidence comes from traits that can be shown to have diverged under natural selection and that now contribute to reproductive isolation. Here, we investigate differential adaptation of two fire-bellied toads (Anura, Bombinatoridae) to two types of aquatic habitat. Bombina bombina and B . variegata are two anciently diverged taxa that now reproduce in predator-rich ponds and ephemeral aquatic sites, respectively. Nevertheless, they hybridise extensively wherever their distribution ranges adjoin. We show in laboratory experiments that, as expected, B . variegata tadpoles are at relatively greater risk of predation from dragonfly larvae, even when they display a predator-induced phenotype. These tadpoles spent relatively more time swimming and so prompted more attacks from the visually hunting predators. We argue in the discussion that genomic regions linked to high activity in B . variegata should be barred from introgression into the B . bombina gene pool and thus contribute to gene flow barriers that keep the two taxa from merging into one.