range edge) and between native-range versus invasive-range populations 10, 11, 12, 13. In the process of that accelerating range expansion, cane toads have accumulated a wide range of heritable differences in traits that affect locomotor ability and resilience to novel abiotic challenges, both within invasive-range populations (range core vs. Although the toad invasion of Australia has been in progress for less than a century, the animals have already expanded their range by thousands of kilometres 9. Some of the best examples of rapidly evolved changes in invasive species come from studies on a South American anuran (the cane toad, Rhinella marina) that was introduced to Australia in 1935 in an ill-considered attempt to control insect pests 8. In response to the opportunities and risks posed by those new interactions, invaders sometimes exhibit remarkably rapid evolved shifts in morphology, physiology, and behaviour 7. A species extending its range into new, unoccupied areas may encounter a suite of novel predators, prey, parasites, competitors and abiotic extremes 5, 6. japonicus population.īiological invasions offer a unique opportunity to examine rapid adaptive changes induced by exposure to new challenges (e.g. Future work could investigate the proximate cues and selective forces responsible for this rapid decrease in rates of cannibalism by tadpoles in an invasive B. Our findings thus support the idea that biological invasions can generate rapid changes in rates of cannibalism, but also show that decreases as well as increases can occur. ![]() japonicus eggs/hatchlings to cannibalism by native-range conspecific tadpoles, and to predation by native-range frog tadpoles. japonicus eggs/hatchlings being more vulnerable than native-range B. This reduction has occurred despite invasive-range B. Contrary to the Australian system, we found that invasion has been accompanied by reduced cannibalistic tendency of B. To explore this question, we collected wild-laid egg clutches of Japanese common toads ( Bufo japonicus) from native and invasive populations in Japan, and conducted laboratory experiments to examine cannibalism responses. Whether such changes in cannibalism occur in invasive populations of other amphibian species is unknown. ![]() For example, cane toad ( Rhinella marina) tadpoles are highly cannibalistic on eggs and hatchlings in their invasive range in Australia, but not in their native range in South America. ![]() Biological invasions can favour rapid changes in intraspecific competitive mechanisms such as cannibalism by imposing novel evolutionary pressures.
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