Spatial variation in egg polymorphism among cuckoo hosts across 4 continents

• 来源期刊: 动物学报（英文版）
• 年，卷（期）: 2020,（5）
• 所属期刊栏目: Articles
• 页码范围: 477-483
• 页数: 7页
• 语种: 英文
• DOI: 10.1093/cz/zoaa011

摘要

Although egg color polymorphism has evolved as an effective defensive adaptation to brood para-sitism,spatial variations in egg color polymorphism remain poorly characterized.Here,we investi-gated egg polymorphism in 647 host species(68 families and 231 genera)parasitized by 41 species of Old Word cuckoos(1 family and 11 genera)across Asia,Europe,Africa,and Australia.The diver-sity of parasitic cuckoos differs among continents,reflecting the continent-specific intensities of parasitic selection pressure on hosts.Therefore,host egg polymorphism is expected to evolve more frequently on continents with higher cuckoo diversity.We identified egg polymorphism in 24.1％of all host species and 47.6％of all host families.The common cuckoo Cuculus canorus uti-lized 184 hosts(28.4％of all host species).Hosts of the common cuckoo and of Chrysococcyx spe-cies were more likely to have polymorphic eggs than hosts parasitized by other cuckoos.Both the number of host species and the host families targeted by the cuckoo species were positively corre-lated with the frequency of host egg polymorphism.Most host species and most hosts exhibiting egg color polymorphism were located in Asia and Africa.Host egg polymorphism was observed less frequently in Australia and Europe.Our results also suggested that egg polymorphism tends to occur more frequently in hosts that are utilized by several cuckoo species or by generalist cuckoo species.We suggest that selection pressure on hosts from a given continent increases pro-portionally to the number of cuckoo species,and that this selection pressure may,in turn,favor the evolution of host egg polymorphism.