Nietlisbach Pirmin, Keller Lukas F, Camenisch Glauco, Guillaume Frédéric, Arcese Peter, Reid Jane M, Postma Erik
Department of Evolutionary Biology and Environmental Studies, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
Department of Evolutionary Biology and Environmental Studies, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland.
Proc Biol Sci. 2017 Mar 15;284(1850). doi: 10.1098/rspb.2016.2763.
Although the pedigree-based inbreeding coefficient predicts the proportion of an individual's genome that is identical-by-descent (IBD), heterozygosity at genetic markers captures Mendelian sampling variation and thereby provides an estimate of IBD. Realized IBD should hence explain more variation in fitness than their pedigree-based expectations, but how many markers are required to achieve this in practice remains poorly understood. We use extensive pedigree and life-history data from an island population of song sparrows () to show that the number of genetic markers and pedigree depth affected the explanatory power of heterozygosity and , respectively, but that heterozygosity measured at 160 microsatellites did not explain more variation in fitness than This is in contrast with other studies that found heterozygosity based on far fewer markers to explain more variation in fitness than Thus, the relative performance of marker- and pedigree-based estimates of IBD depends on the quality of the pedigree, the number, variability and location of the markers employed, and the species-specific recombination landscape, and expectations based on detailed and deep pedigrees remain valuable until we can routinely afford genotyping hundreds of phenotyped wild individuals of genetic non-model species for thousands of genetic markers.
尽管基于系谱的近亲繁殖系数可预测个体基因组中同源纯合（IBD）的比例，但遗传标记处的杂合性反映了孟德尔抽样变异，从而提供了IBD的估计值。因此，实际的IBD应该比基于系谱的预期能解释更多的适合度变异，但在实践中需要多少标记才能实现这一点仍知之甚少。我们使用来自歌带鹀岛屿种群的广泛系谱和生活史数据表明，遗传标记的数量和系谱深度分别影响杂合性的解释力，但在160个微卫星处测量的杂合性并不能比基于系谱的近亲繁殖系数解释更多的适合度变异。这与其他研究形成对比，那些研究发现基于少得多的标记的杂合性比基于系谱的近亲繁殖系数能解释更多的适合度变异。因此，基于标记和系谱的IBD估计的相对表现取决于系谱的质量、所用标记的数量、变异性和位置，以及物种特异性的重组格局，并且在我们能够常规地为数千个遗传标记对数百个表型野生非模式物种个体进行基因分型之前，基于详细和深入系谱的预期仍然很有价值。
