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Résumé :
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We present a model for the evolution of host selection by avian brood parasites from the ecological context of siblicidal brood reduction tactics. Our analysis concentrates on the fitness costs and benefits that permit the evolution of brood parasitism as an adaptive strategy from a state of obligate parental care already featuring siblicide. Limited resources delivered by provisioning parents may incite siblicidal behaviour in offspring, directed towards nestmates regardless of kinship. The extent of siblicidal behaviour (in frequency of occurrence and number of nestmates killed) can extend to the eradication of all nestmates, as has been observed in some raptors and in seabirds. For parents of siblicidal offspring, laying each egg parasitically may maximize offspring survival by eliminating competition between related but siblicidal nest mates. To permit the evolution of conspecific (intraspecific) brood parasitism, costs of siblicide by the offspring of parasitic parents must exceed costs paid by the parasitic parents when losing related conspecifics (host offspring) in a host nest. To permit the evolution of obligate interspecific brood parasitism, costs to fitness from siblicidal offspring or nest reduction of related hosts must exceed costs of heterospecific parental care. Understanding the kin structure between parasites and hosts in conspecific parasitism, and measuring the costs paid by parasitic young due to mismatched incubation, provisioning, and social behaviours by heterospecific foster parents, should provide novel insights into the opportunities and constraints of the evolution of avian brood parasitism.
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