Markert J A, Grant P R, Grant B R, Keller L F, Coombs J L, Petren K
Department Ecology and Evolutionary Biology, Princeton University, Princeton, NJ 08544-1003, USA.
Heredity (Edinb). 2004 Apr;92(4):306-15. doi: 10.1038/sj.hdy.6800409.
Comprehensive long-term studies of isolated populations provide valuable comparative data that may be used to evaluate different methods for quantifying the relationship between genetic diversity and fitness. Here, we report on data collected from large and well-characterized cohorts of the two numerically dominant species of Darwin's finches on Isla Daphne Major, Galápagos, Ecuador - Geospiza fortis and G. scandens. Multilocus microsatellite (SSR) genetic diversity estimates (heterozygosity and d2) and pedigree-based estimates of the inbreeding coefficient (f) were compared to each other and to two fitness components: lifespan and recruitment. In the larger sample of G. fortis, heterozygosity (H) was correlated with both fitness components, but no relationship was detected in the smaller sample of G. scandens. Analyses of the inbreeding coefficient detected highly significant relationships between f and recruitment, but no relationship between f and overall lifespan. The d2 statistic showed no relationship to either fitness component. When the two SSR-based estimators were compared to f, d2 was correlated with f in G. fortis in the predicted direction, while in G. scandens the relationship was positive. Multilocus heterozygosity was correlated with f in G. fortis but not in the G. scandens sample. A pedigree simulation demonstrated that the variation in true autozygosity can be large among individuals with the same level of inbreeding. This observation may supplement the interpretation of patterns relevant to the local (locus-specific) and general (genome-wide) effects hypotheses, which have been proposed to explain the mechanism responsible for associations between genetic diversity and fitness.
对隔离种群进行全面的长期研究可提供有价值的比较数据，这些数据可用于评估量化遗传多样性与适应性之间关系的不同方法。在此，我们报告了从厄瓜多尔加拉帕戈斯群岛达芙妮主岛上数量占优势的两种达尔文雀——强壮地雀和仙人掌地雀的大型且特征明确的队列中收集的数据。将多基因座微卫星（SSR）遗传多样性估计值（杂合度和d2）以及基于系谱的近交系数（f）估计值相互比较，并与两个适应性成分：寿命和繁殖成功率进行比较。在较大的强壮地雀样本中，杂合度（H）与两个适应性成分均相关，但在较小的仙人掌地雀样本中未检测到相关性。对近交系数的分析检测到f与繁殖成功率之间存在高度显著的关系，但f与总体寿命之间没有关系。d2统计量与任何一个适应性成分均无关系。当将基于SSR的两个估计值与f进行比较时，d2在强壮地雀中与f呈预测方向的相关性，而在仙人掌地雀中这种关系是正相关的。多基因座杂合度在强壮地雀中与f相关，但在仙人掌地雀样本中不相关。系谱模拟表明，在具有相同近交水平的个体中，真实纯合度的变异可能很大。这一观察结果可能补充了对与局部（基因座特异性）和一般（全基因组）效应假说相关模式的解释，这些假说是为了解释遗传多样性与适应性之间关联的机制而提出的。
