Research groups at the Tokyo University of Agriculture and Technology, the National Institute for Environmental Studies, and the Forestry Research Institute have found that the escape behavior of the endangered frog (Amami Hanasaki frog) on Amami Oshima is limited by the invasive alien species, the small Indian mongoose. It developed rapidly over the decades, revealing that the changes did not return when the mongoose was eradicated.
Since the island's native frogs do not originally have predators, they have less "escape" behavior and are easily eaten by new foreign predators.Among them, individuals who escape even a little are likely to survive, and there is a possibility that escape behavior will develop as a group evolution across generations.However, in the past, attention was focused only on the effect on the population.
Introduced to Amami Oshima in 1979, mongoose has reduced many native species in areas near the point of introduction. Mongoose has been largely exterminated since 2000, but if the escape behavior of native species has evolved, it is expected that the change will continue even if the mongoose disappears.For verification, in August 2013, the research group measured the "escape start distance" of how close a person should be to escape in an area where the influence of mongoose (distance from the introduction point) is different.
As a result, frogs whose habitat was closer to the mongoose introduction point escaped sooner.This revealed that foreign mongoose may have rapidly evolved frog escape behavior in just a few decades (a dozen generations), and that once developed escape behavior may not return immediately.It has been found that alien species reduce the number of native species and also change the nature of behavior.
It is expected that the results of this research will allow us to properly understand the magnitude and breadth of the effects of alien species on native species by evaluating them from the perspective of changes in properties.
Paper information:[Journal of Zoology] Rapid behavioral responses of native frogs caused by past predation pressure from invasive mongooses
