The imprecision of heterozygosity-fitness correlations hinders the detection of inbreeding and inbreeding depression in a threatened species
The imprecision of heterozygosity-fitness correlations hinders the detection of inbreeding and inbreeding depression in a threatened species
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DOI：
10.1111/j.1365-294x.2010.04930.x
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发表时间：
2011-01-01
影响因子：
4.9
通讯作者：
Jamieson, Ian G.
中科院分区：
文献类型：
--
作者：
Grueber, Catherine E.;Waters, Jonathan M.;Jamieson, Ian G.
在非纯系野生种群中，近交衰退通常通过使用基于相关性的分子估计的杂合性-适应度相关性（HFC）来量化。尽管这种相关性通常被解释为近交衰退的证据，但通过假设标记杂合性是全基因组杂合性的代表，理论预测这些关系应该很难检测到。到目前为止，该领域的绝大多数实证研究都是在一般远交、非瓶颈种群中进行的，但种群遗传过程的差异可能会限制将结果外推到受威胁种群。在这里，我们对氢氟碳化合物进行了分析，及其对解释近亲繁殖的影响，在一个瓶颈物种的自由放养纯种种群中：濒临灭绝的南高芥（Porphyrio hochstetteri）。已经在该物种中发现了基于谱系的近交衰退。使用 23 个微卫星位点，我们仅观察到多位点杂合性与个体生命史阶段（例如存活到孵化和羽翼未丰）的适应性之间预期关系的微弱证据，并且参数估计不精确（误差较高）。此外，我们的分子数据集无法准确预测个体的近交状态（根据谱系确定为“近交”或“远交”），也无法表明观察到的 HFC 是全基因组身份不平衡的结果。这些结果可能归因于近交类内杂合性的高方差。这项研究是来自自由放养的濒危物种的经验例子，表明即使数量相对较大（> 20）的微卫星也可能在估计个体全基因组杂合性时精度较差。我们认为，谱系方法仍然是量化野生种群近亲繁殖的最有效方法，特别是那些经历了严重瓶颈的种群。
In nonpedigreed wild populations, inbreeding depression is often quantified through the use of heterozygosity-fitness correlations (HFCs), based on molecular estimates of relatedness. Although such correlations are typically interpreted as evidence of inbreeding depression, by assuming that the marker heterozygosity is a proxy for genome-wide heterozygosity, theory predicts that these relationships should be difficult to detect. Until now, the vast majority of empirical research in this area has been performed on generally outbred, nonbottlenecked populations, but differences in population genetic processes may limit extrapolation of results to threatened populations. Here, we present an analysis of HFCs, and their implications for the interpretation of inbreeding, in a free-ranging pedigreed population of a bottlenecked species: the endangered takahe (Porphyrio hochstetteri). Pedigree-based inbreeding depression has already been detected in this species. Using 23 microsatellite loci, we observed only weak evidence of the expected relationship between multilocus heterozygosity and fitness at individual life-history stages (such as survival to hatching and fledging), and parameter estimates were imprecise (had high error). Furthermore, our molecular data set could not accurately predict the inbreeding status of individuals (as 'inbred' or 'outbred', determined from pedigrees), nor could we show that the observed HFCs were the result of genome-wide identity disequilibrium. These results may be attributed to high variance in heterozygosity within inbreeding classes. This study is an empirical example from a free-ranging endangered species, suggesting that even relatively large numbers (> 20) of microsatellites may give poor precision for estimating individual genome-wide heterozygosity. We argue that pedigree methods remain the most effective method of quantifying inbreeding in wild populations, particularly those that have gone through severe bottlenecks.