|
Brood parasites are organisms that rely on others to raise their young. The strategy appears among insects, fishes, and birds. The brood parasite manipulates a host, either of the same or of another species, to raise its young as if it were its own. Brood parasitism relieves the parasitic parents from the investment of rearing young or building nests for the young, enabling them to spend more time on other activities such as foraging and producing further offspring. Bird parasite species mitigate the risk of egg loss by distributing eggs amongst a number of different hosts. As this behaviour damages the host, it often results in an evolutionary arms race between parasite and host.〔 Payne, R. B. 1997. Avian brood parasitism. In D. H. Clayton and J. Moore (eds.), Host-parasite evolution: General principles and avian models, 338–369. Oxford University Press, Oxford.〕〔Rothstein, S.I, 1990. A model system for coevolution: avian brood parasitism. Annual Review of Ecology and Systematics 21: 481-508.〕 ==Birds== In many monogamous bird species, there are extra-pair matings resulting in males outside the pair bond siring offspring and used by males to escape from the parental investment in raising their offspring.〔Stephen M. Yezerinac, Patrick J. Weatherhead 1997. Extra-Pair Mating, Male Plumage Coloration and Sexual Selection in yellow warblers (''Dendroica petechia''). Proc. R. Soc. London B. 264(1381):527–532〕 This form of cuckoldry is taken a step further when females of the goldeneye, ''Bucephala clangula'' often lay their eggs in the nests of other individuals. Intraspecific brood parasitism is seen in a number of duck species, where females often lay their eggs in the nests of others.〔Andersson, M. & Eriksson, M.O.G. 1982 Nest parasitism in goldeneyes ''Bucephala clangula'': some evolutionary aspects. American Naturalist 120, 1–16 (1982)〕 Interspecific brood-parasites include the Old World cuckoo, cowbirds, black-headed ducks, and some New World cuckoos in the Americas, and indigobirds, whydahs, and honeyguides in Africa. Seven independent origins of obligate interspecific brood parasitism in birds have been proposed. While there is still some controversy over when and how many origins of interspecific brood parasitism have occurred, recent phylogenetic analyses suggest two origins in Passeriformes (once in New World cowbirds: Icteridae, and once in African Finches: Viduidae); three origins in Old World and New World cuckoos (once in Cuculinae, Phaenicophaeinae, and in Neomorphinae-Crotophaginae); a single origin in Old World honeyguides (Indicatoridae); and in a single species of waterfowl, the black-headed duck (''Heteronetta atricapilla'').〔Aragon, S., A. P. Møller, J. J. Soler, and M. Soler, 1999. Molecular phylogeny of cuckoos supports a polyphyletic origin of brood parasitism. Journal of Evolutionary Biology 12: 495–506〕〔Sorenson, M.D, and R.B. Payne, 2001. A single ancient origin of brood parasitism in African finches: implications for host-parasite coevolution. Evolution: 55: 2550-2567〕〔Sorenson, M.D., and R.B. Payne, 2002. Molecular genetic perspectives on avian brood parasitism. Integrative and Comparative Biology 42: 388–400〕 Most avian brood parasites are specialists which will only parasitize a single host species or a small group of closely related host species, but four out of the five parasitic cowbirds are generalists, which parasitize a wide variety of hosts; the brown-headed cowbird has 221 known hosts. They usually only lay one egg per nest, although in some cases, particularly the cowbirds, several females may use the same host nest. The common cuckoo presents an interesting case in which the species as a whole parasitizes a wide variety of hosts, including the Reed Warbler and dunnock, but individual females specialize in a single species. Genes regulating egg coloration appear to be passed down exclusively along the maternal line, allowing females to lay mimetic eggs in the nest of the species they specialize in. Females generally parasitize nests of the species which raised them. Male Common Cuckoos will fertilize females of all lines, maintaining sufficient gene flow among the different maternal lines.〔Vogl W., M. Taborsky, B. Taborsky, Y. Teuschl, and M. Honza. (2002) Cuckoo females preferentially use specific habitats when searching for hot nests. Animal Behavior 64: 843–850〕 The mechanisms of host selection by female cuckoos are somewhat unclear, though several hypotheses have been suggested in attempt to explain the choice. These include genetic inheritance of host preference, host imprinting on young birds, returning to place of birth and subsequently choosing a host randomly ("natal philopatry"), choice based on preferred nest site (nest-site hypothesis), and choice based on preferred habitat (habitat-selection hypothesis). Of these hypotheses the nest-site selection and habitat selection have been most supported by experimental analysis.〔〔Teuschl Y, B Taborsky, and M Taborsky. (1998) How do cuckoos find their hosts? The role of habitat imprinting. Animal Behavior 56: 1425-1433〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「brood parasite」の詳細全文を読む スポンサード リンク
|