Affiliation:
1. Department of Zoology, Palacky Universitytr. Svobody 26, 771 46 Olomouc, Czech Republic
Abstract
Recognition is considered a critical basis for discriminatory behaviours in animals. Theoretically, recognition and discrimination of parasitic chicks are not predicted to evolve in hosts of brood parasitic birds that evict nest-mates. Yet, an earlier study showed that host reed warblers (
Acrocephalus scirpaceus
) of an evicting parasite, the common cuckoo (
Cuculus canorus
), can avoid the costs of prolonged care for unrelated young by deserting the cuckoo chick before it fledges. Desertion was not based on specific recognition of the parasite because hosts accept any chick cross-fostered into their nests. Thus, the mechanism of this adaptive host response remains enigmatic. Here, I show experimentally that the cue triggering this ‘discrimination without recognition’ behaviour is the duration of parental care. Neither the intensity of brood care nor the presence of a single-chick in the nest could explain desertions. Hosts responded similarly to foreign chicks, whether heterospecific or experimental conspecifics. The proposed mechanism of discrimination strikingly differs from those found in other parasite–host systems because hosts do not need an internal recognition template of the parasite's appearance to effectively discriminate. Thus, host defences against parasitic chicks may be based upon mechanisms qualitatively different from those operating against parasitic eggs. I also demonstrate that this discriminatory mechanism is non-costly in terms of recognition errors. Comparative data strongly suggest that parasites cannot counter-evolve any adaptation to mitigate effects of this host defence. These findings have crucial implications for the process and end-result of host–parasite arms races and our understanding of the cognitive basis of discriminatory mechanisms in general.
Subject
General Agricultural and Biological Sciences,General Environmental Science,General Immunology and Microbiology,General Biochemistry, Genetics and Molecular Biology,General Medicine
Reference36 articles.
1. Parent-offspring recognition in bank swallows (Riparia riparia): II. Development and acoustic basis
2. Britton N. F. Planqué R. & Franks N. R. In press. Evolution of defence portfolios in exploiter-victim systems. Bull. Math. Biol .
3. Cramp S. (ed.) 1992 Handbook of the birds of Europe the Middle East and North Africa. The birds of the Western Palearctic . vol. VI Warblers p. 728. Oxford UK: University Press.
4. Davies N.B Cuckoos cowbirds and other cheats. 2000 London UK:T & A.D. Poyser.
5. An Experimental Study of Co-Evolution between the Cuckoo, Cuculus canorus, and its Hosts. II. Host Egg Markings, Chick Discrimination and General Discussion
Cited by
95 articles.
订阅此论文施引文献
订阅此论文施引文献,注册后可以免费订阅5篇论文的施引文献,订阅后可以查看论文全部施引文献