Data from: Inbreeding and inbreeding avoidance in wild giant pandas

Inbreeding can have negative consequences on population and individual fitness, which could be counteracted by inbreeding avoidance mechanisms. However, the inbreeding risk and inbreeding avoidance mechanisms in endangered species are less studied. The giant panda, a solitary and threatened species, lives in many small populations and suffers from habitat fragmentation, which may aggravate the risk of inbreeding. Here, we performed long-term observations of reproductive behaviour, sampling of mother-cub pairs and large-scale genetic analyses on wild giant pandas. Moderate levels of inbreeding were found in 21.1% of mating-pairs, 9.1% of parent-pairs and 7.7% of panda cubs, but no high-level inbreeding occurred. More significant levels of inbreeding may be avoided passively by female-biased natal dispersal rather than by breeding dispersal or active relatedness-based mate choice mechanisms. The level of inbreeding in giant pandas is greater than expected for a solitary mammal and thus warrants concern for potential inbreeding depression, particularly in small populations isolated by continuing habitat fragmentation, which will reduce female dispersal and increase the risk of inbreeding.

近交（inbreeding）会对种群适合度与个体适合度产生负面影响，此类负面影响可通过近交回避机制予以抵消。然而，目前针对濒危物种的近交风险与近交回避机制的研究仍相对匮乏。大熊猫作为独居且受胁的物种，栖息于诸多小型种群中，且受栖息地破碎化影响，这可能加剧近交风险。本研究针对野生大熊猫开展了长期繁殖行为观测、母幼对采样以及大规模遗传分析。研究发现，21.1%的交配对、9.1%的亲本对以及7.7%的大熊猫幼崽存在中等程度的近交，但未出现高水平近交现象。相较于繁殖扩散（breeding dispersal）或基于亲缘关系的主动配偶选择机制（active relatedness-based mate choice），偏雌性的出生扩散（natal dispersal）或可被动规避更严重的近交风险。大熊猫的近交水平高于独居哺乳动物的预期值，因此需对潜在的近交衰退（inbreeding depression）风险予以关注，尤其是在因持续栖息地破碎化而相互隔离的小型种群中，此类生境破碎化会降低雌性个体的扩散能力，进一步提升近交风险。