Research press release


Nature Communications

Ecology: Why some caterpillars hide and some holler



今回、Johanna Mappesたちは、さまざまな色のチョウやガの幼虫の数が捕食者の幼鳥の数によって影響を受けるかどうかを調べた。幼鳥は、初めて巣を離れる時に、派手な体色の被食者が示す警告シグナルの意味を知らない。


Seasonal differences in the survival of caterpillars, conspicuous versus camouflaged, depends on the learning and experience of young birds, reports a study published in Nature Communications this week. This time-lag in predator learning could explain why conspicuous prey are rare at certain times of the year.

To avoid being eaten, caterpillars of different butterfly species have evolved to either blend into their backgrounds or advertise themselves as harmful to would-be predators using conspicuous ‘warning’ signals. However, conspicuous advertising is a risky strategy as it relies on predators understanding what these signals mean.

Johanna Mappes and colleagues investigated whether the abundance of differently coloured caterpillar species might be influenced by the number of juvenile bird predators, which are naive to the meaning of warning signals from conspicuously coloured prey, when they first leave the nest.

The authors find that conspicuously coloured caterpillars have improved survival at the beginning and end of the fledging season, when naive birds are least abundant, while camouflaged species have a survival advantage during the middle season. These same seasonal abundance patterns are reflected in nature across many caterpillar species of differing colours, and could explain why warning signals persist when predators have no innate knowledge of their meaning.

doi: 10.1038/ncomms6016

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