Coevolutionary arms race and sympatric speciation in tropical cuckoos: the role of visual mimicry in parasitic chicks

2015 Fiscal Year Final Research Report

• Project/Area Number: 24770028
• Research Category: Grant-in-Aid for Young Scientists (B)
• Allocation Type: Multi-year Fund
• Research Field: Ecology/Environment
• Research Institution: Rikkyo University
• Principal Investigator: TANAKA Keita 立教大学, 理学部, 特定課題研究員 (30625059)
• Project Period (FY): 2012-04-01 – 2016-03-31
• Keywords: 托卵鳥 / 軍拡競争共進化 / 熱帯 / 視覚擬態 / 識別 / 色彩多型

Outline of Final Research Achievements

Brood parasitic birds exploit parental care of host species by laying their eggs in host nests. In most brood parasites, parasitic eggs mimic host eggs in appearance, which should have evolved to evade host parents’ discrimination. In bronze-cuckoos, distributing in tropical Asia and Oceania, parasitic chicks are known to mimic host chicks. I investigated a bronze-cuckoo in New Caledonia, and discovered polymorphism in nestling skin colour both in the cuckoo and its host: chicks have either dark or pale skin, clearly different from each other. This polymorphism would be a consequence of the escalating coevolutionary arms race between them. Chick mimicry first evolved in the parasite to evade host discrimination. Then, a novel chick skin colour evolved in the host to escape parasite’s mimicry, which triggered the evolution of mimics of the novel-coloured host chick in the parasite to catch up with the host. This was the first ever discovery of chick polymorphism in wild birds.

Free Research Field

認知・進化・行動生態