Lieutenant-Gosselin Mélissa, Bernatchez Louis
Département de biologie, Québec-Océan, Université Laval, Sainte-Foy, Québec G1K 7P4, Canada.
Evolution. 2006 Aug;60(8):1658-68.
The complex interactions between genetic diversity and evolution have important implications in many biological areas including conservation, speciation, and mate choice. A common way to study these interactions is to look at heterozygosity-fitness correlations (HFCs). Until recently, HFCs based on noncoding markers were believed to result primarily from global inbreeding effects. However, accumulating theoretical and empirical evidence shows that HFCs may often result from genes being linked to the markers used (local effect). Moreover, local effect HFCs could differ from global inbreeding effects in their direction and occurrence. Consequently, the investigation of the structure and consequences of local HFCs is emerging as a new important goal in evolutionary biology. In this study of a wild threespine stickleback (Gasterosteus aculeatus) population, we first tested the presence of significant positive or negative local effects of heterozygosity at 30 microsatellites loci on five fitness components: survival, mating success, territoriality, length, and body condition. Then, we evaluated the direction and shape of total impact of local HFCs, and estimated the magnitude of the impacts on fitness using regression coefficients and selection differentials. We found that multilocus heterozygosity was not a reliable estimator of individual inbreeding coefficient, which supported the relevance of single-locus based analyses. Highly significant and temporally stable local HFCs were observed. These were mainly positive, but negative effects of heterozygosity were also found. Strong and opposite effects of heterozygosity are probably present in many populations, but may be blurred in HFC analyses looking for global effects only. In this population, both negative and positive HFCs are apparently driving mate preference by females, which is likely to contribute to the maintenance of both additive and nonadditive genetic variance.
遗传多样性与进化之间的复杂相互作用在包括保护、物种形成和配偶选择在内的许多生物学领域都具有重要意义。研究这些相互作用的一种常见方法是观察杂合度-适合度相关性（HFCs）。直到最近，基于非编码标记的HFCs被认为主要是由全局近亲繁殖效应导致的。然而，越来越多的理论和实证证据表明，HFCs可能经常是由与所用标记连锁的基因（局部效应）导致的。此外，局部效应HFCs在其方向和发生情况上可能与全局近亲繁殖效应不同。因此，对局部HFCs的结构和后果的研究正在成为进化生物学中的一个新的重要目标。在这项对野生三刺鱼（Gasterosteus aculeatus）种群的研究中，我们首先测试了30个微卫星位点的杂合度对五个适合度成分（生存、交配成功率、领地性、体长和身体状况）的显著正效应或负效应是否存在。然后，我们评估了局部HFCs的总影响的方向和形状，并使用回归系数和选择差异估计了对适合度的影响程度。我们发现多位点杂合度不是个体近亲繁殖系数的可靠估计指标，这支持了基于单一位点分析的相关性。观察到了高度显著且随时间稳定的局部HFCs。这些主要是正效应，但也发现了杂合度的负效应。杂合度的强烈且相反的效应可能在许多种群中都存在，但在仅寻找全局效应的HFC分析中可能会被掩盖。在这个种群中，正负HFCs显然都在驱动雌性的配偶偏好，这可能有助于维持加性和非加性遗传方差。
