Data from: A high quality pedigree and genetic markers both reveal inbreeding depression for quality but not survival in a cooperative mammal

Inbreeding depression, the reduced fitness of offspring of closely related parents, is commonplace in both captive and wild populations and has important consequences for conservation and mating system evolution. However, because of the difficulty of collecting pedigree and life history data from wild populations, relatively few studies have been able to compare inbreeding depression for traits at different points in the life cycle. Moreover, pedigrees give the expected proportion of the genome that is identical by descent (IBDg) whereas in theory with enough molecular markers realised IBDg can be quantified directly. We therefore investigated inbreeding depression for multiple life-history traits in a wild population of banded mongooses using pedigree-based inbreeding coefficients (fped) and standardised multilocus heterozygosity (sMLH) measured at 35-43 microsatellites. Within an information theoretic framework, we evaluated support for either fped or sMLH as inbreeding terms and used sequential regression to determine whether the residuals of sMLH on fped explain fitness variation above and beyond fped. We found no evidence of inbreeding depression for survival, either before or after nutritional independence. By contrast, inbreeding was negatively associated with two quality related traits, yearling body mass and annual male reproductive success. Yearling body mass was associated with fped but not sMLH, while male annual reproductive success was best explained by both fped and residual sMLH. Thus, our study not only uncovers variation in the extent to which different traits show inbreeding depression, but also reveals trait-specific differences in the ability of pedigrees and molecular markers to explain fitness variation and suggests that for certain traits genetic markers may capture variation in realised IBDg above and beyond the pedigree expectation.

近交衰退（inbreeding depression）指亲缘相近的亲本所产后代的适合度降低，该现象在圈养与野生种群中均普遍存在，对物种保护与交配系统演化具有重要意义。然而，由于难以从野生种群中获取谱系数据与生活史信息，能够比较不同生活史阶段性状的近交衰退程度的研究相对匮乏。此外，谱系仅能给出基因组通过同源纯合（identity by descent, IBDg）的预期比例，而理论上，若拥有足够多的分子标记，即可直接量化实际同源纯合比例（realised IBDg）。为此，本研究针对斑獴（banded mongooses）的一个野生种群，基于35至43个微卫星（microsatellites）位点测得的基于谱系的近交系数（pedigree-based inbreeding coefficients, fped）与标准化多位点杂合度（standardised multilocus heterozygosity, sMLH），探究了多个生活史性状的近交衰退情况。在信息论框架下，我们评估了以fped或sMLH作为近交指标的支持程度，并通过序贯回归分析，检验sMLH相对于fped的残差是否能够解释fped未覆盖的适合度变异。研究结果显示，无论在营养独立期前还是其后，存活相关性状均未表现出近交衰退迹象。与之形成对比的是，近交与两项与个体质量相关的性状呈负相关：一岁龄个体体重与雄性年度繁殖成功率。其中，一岁龄个体体重仅与fped显著相关，而与sMLH无明显关联；雄性年度繁殖成功率则可通过fped与残差sMLH得到最佳解释。因此，本研究不仅揭示了不同性状的近交衰退程度存在差异，还发现谱系与分子标记在解释适合度变异方面的能力因性状而异，并表明针对部分性状，遗传标记能够捕捉到超出谱系预期的实际同源纯合比例变异。