SYMPATRIC AND ALLOPATRIC HOST POPULATIONS
SYMPATRIC AND ALLOPATRIC HOST POPULATIONS
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同源和异源宿主种群
DOI：
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发表时间：
1992
期刊：
影响因子：
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通讯作者：
A. Hobson
中科院分区：
文献类型：
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作者：
J. Briskie;S. Sealy;A. Hobson
褐头燕八哥（Molothrus ater）是北美雀形目鸟类的一种广泛分布的专性育雏寄生虫。在南部马尼托巴，其中主机是同域与燕八哥，美国知更鸟（Turdus migratorius）喷射寄生卵从所有实验寄生离合器（N = 25），没有鸡蛋被接受超过四天。相比之下，知更鸟在北方马尼托巴，燕八哥不繁殖的地区，接受寄生卵在33%的巢（N = 18）至少五天。接受实验燕八哥卵的第二主机，黄莺（Dendroica petechia），是类似的异域（100%的20个巢）和同域（88.6%的35个巢）的人口，但模型的女性燕八哥引起更大的巢防御莺在同域。两种宿主都不排斥同种的卵，因此，对燕八哥卵的排斥并不是同种育雏寄生的附带现象。这些结果支持了这样的假设，即燕八哥及其卵的再认知是作为对抗燕八哥寄生的适应而进化的，而不是其他选择压力。一些个体在异域种群中抗寄生虫防御的表达进一步表明，这些特征可能受到遗传控制，但通过同域种群中排斥基因的持续渗入或由于寄生虫不存在或罕见时排斥行为的低成本而在这些地区持续存在。
The brown-headed cowbird (Molothrus ater) is a widespread, obligate brood parasite of North American passerine birds. In southern Manitoba, where hosts are sympatric with cowbirds, American robins (Turdus migratorius) ejected parasitic eggs from all experimentally parasitized clutches (N = 25) and no eggs were accepted for more than four days. In contrast, robins in northern Manitoba, an area where cowbirds do not breed, accepted parasitic eggs in 33% of nests (N = 18) for at least five days. Acceptance of experimental cowbird eggs by a second host, the yellow warbler (Dendroica petechia), was similar in allopatric (100% of 20 nests) and sympatric (88.6% of 35 nests) populations, but models of a female cowbird elicited greater nest defense by warblers in the area of sympatry. Neither host rejected eggs of conspecifics, thus, rejection of cowbird eggs was not an epiphenomenon of conspecific brood parasitism. These results support the hypothesis that rec- ognition of cowbirds and their eggs evolved as adaptations to counter cowbird parasitism and not some other selection pressure. The expression of anti-parasite defenses by some individuals within allopatric populations further suggests these traits may be controlled genetically but persist in such areas either through the continued introgression of rejecter genes from sympatric populations or because of the low cost of rejection behavior when parasitism is absent or rare.