Data from: Within- and among-population impact of genetic erosion on adult fitness-related traits in the European tree frog Hyla arborea

Assessing in wild populations how fitness is impacted by inbreeding and genetic drift is a major goal for conservation biology. An approach to measure the detrimental effects of inbreeding on fitness is to estimate correlations between molecular variation and phenotypic performances within and among populations. Our study investigated the effect of individual multilocus heterozygosity on body size, body condition and reproductive investment of males (that is, chorus attendance) and females (that is, clutch mass and egg size) in both small fragmented and large non-fragmented populations of European tree frog (Hyla arborea). Because adult size and/or condition and reproductive investment are usually related, genetic erosion may have detrimental effects directly on reproductive investment, and also on individual body size and condition that in turn may affect reproductive investment. We confirmed that the reproductive investment was highly size-dependent for both sexes. Larger females invested more in offspring production, and larger males attended the chorus in the pond more often. Our results did not provide evidence for a decline in body size, condition and reproductive effort with decreased multilocus heterozygosity both within and among populations. We showed that the lack of heterozygosity–fitness correlations within populations probably resulted from low inbreeding levels (inferior to ca. 20% full-sib mating rate), even in the small fragmented populations. The detrimental effects of fixation load were either low in adults or hidden by environmental variation among populations. These findings will be useful to design specific management actions to improve population persistence.探究野生种群中适合度（fitness）如何受到近交（inbreeding）与遗传漂变（genetic drift）的影响，是保护生物学（conservation biology）的核心研究目标之一。评估近交对适合度产生的有害影响的常用方法，是估算种群内部及种群间分子变异（molecular variation）与表型表现（phenotypic performance）之间的相关性。本研究以欧洲树蛙（Hyla arborea）的小型破碎化种群与大型非破碎化种群为研究对象，探究个体多位点杂合性（multilocus heterozygosity）对雄性及雌性的体型、身体状况与繁殖投入（reproductive investment）的影响：雄性的繁殖投入以鸣唱集群出席率表征，雌性则以产卵团质量与卵粒大小表征。由于成体体型或身体状况通常与繁殖投入存在关联，因此遗传侵蚀（genetic erosion）可能会直接对繁殖投入产生有害影响，同时也会作用于个体体型与身体状况，而后者又会进一步影响繁殖投入。本研究证实，两性的繁殖投入均与体型高度相关：体型更大的雌性在后代生产上的投入更多，体型更大的雄性则更频繁地前往池塘参与鸣唱集群。我们的研究结果并未发现，在种群内部及种群间，随着多位点杂合性降低，个体的体型、身体状况与繁殖投入会出现下降的证据。我们的分析表明，即便在小型破碎化种群中，种群内部缺乏杂合性-适合度相关性（heterozygosity–fitness correlations）的现象，大概率源于较低的近交水平（全同胞交配率（full-sib mating rate）约低于20%）。固定负荷（fixation load）所带来的有害影响，要么在成体阶段表现较弱，要么被种群间的环境差异所掩盖。上述研究结果可为制定针对性的种群管理方案以提升种群存续能力提供理论参考。