Heterozygosity-fitness correlations in a bottlenecked island species: a case study on the Seychelles warbler
Heterozygosity-fitness correlations in a bottlenecked island species: a case study on the Seychelles warbler
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DOI：
10.1111/j.1365-294x.2007.03370.x
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发表时间：
2007-08-01
影响因子：
4.9
通讯作者：
Richardson, D. S.
中科院分区：
文献类型：
--
作者：
Brouwer, L.;Komdeur, J.;Richardson, D. S.
本文采用捕获-标记-再捕获模型研究了个体和亲本杂合度对塞舌尔莺（Acrocephalus sechellensis）生存的影响，该物种是一种特有的岛屿物种，在上世纪中叶经历了严重的种群瓶颈。我们发现个体的生存与多位点杂合性或任何特定位点的杂合性无关。然而，母亲的多位点杂合性与后代存活率呈正相关，而不是父亲的，但仅在低存活率的年份。一项交叉抚养雏鸟的实验表明，这是一种直接的母性影响，因为这是遗传母亲的杂合性的影响，而不是社会母亲的杂合性。微卫星标记上的杂合度-适应度相关性通常被认为反映了全基因组效应。虽然这在部分近亲繁殖的种群中可能是正确的，但这种相关性也可能是由于与决定适应性的基因密切相关的特定标记的局部效应而产生的。然而，单个微卫星位点的杂合性不相关，因此似乎不能反映全基因组的杂合性。这表明，即使在一个小的瓶颈群体中，杂合度-适应度相关性也可能不是由全基因组效应引起的。对局部效应假说的支持也是模棱两可的；虽然有三个特定的基因座与后代的生存有关，但包括所有的单位点杂合性作为生存变异的独立预测因子的数据并不支持。此外，与局部效应假说相反，对杂合性-生存关系贡献最大的位点并不比其他位点更具多态性。这项研究突出了区分这两种假设的困难。
We used capture-mark-recapture models to investigate the effects of both individual and parental heterozygosity, measured at microsatellite loci on the survival of Seychelles warblers (Acrocephalus sechellensis), an endemic island species which went through a severe population bottleneck in the middle of the last century. We found that an individual's survival was not correlated with multilocus heterozygosity, or with heterozygosity at any specific locus. However, maternal, but not paternal, multilocus heterozygosity was positively associated with offspring survival, but only in years with low survival probabilities. A nestling cross-fostering experiment showed that this was a direct maternal effect as there was an effect of the genetic mother's, but not of the social mother's, heterozygosity. Heterozygosity-fitness correlations at microsatellite markers were generally assumed to reflect genome-wide effects. Although this might be true in partially inbred populations, such correlations may also arise as a result of local effects with specific markers being closely linked to genes which determine fitness. However, heterozygosity at the individual microsatellite loci was not correlated and therefore does not seem to reflect genome-wide heterozygosity. This suggests that even in a small bottlenecked population, heterozygosity-fitness correlations may not be caused by genome-wide effects. Support for the local effects hypothesis was also equivocal; although three specific loci were associated with offspring survival, including all single-locus heterozygosities as independent predictors for the variation in survival was not supported by the data. Furthermore, in contrast to the local effects hypothesis, the loci which contributed most to the heterozygosity-survival relationship were not more polymorphic than the other loci. This study highlights the difficulties in distinguishing between the two hypotheses.