Data from: Escape from predators and genetic variance in birds

Predation is a common cause of death in numerous organisms, and a host of anti-predator defenses have evolved. Such defenses often have a genetic background as shown by significant heritability and micro-evolutionary responses towards weaker defenses in the absence of predators. Flight initiation distance (FID) is the distance at which an individual animal takes flight when approached by a human, and hence it reflects the life history compromise between risk of predation and the benefits of foraging. Here we analyzed FID in 128 species of birds in relation to three measures of genetic variation, band sharing coefficient for minisatellites, observed heterozygosity and inbreeding coefficient for microsatellites in order to test whether FID was positively correlated with genetic variation. We found consistently shorter FID for a given body size in the presence of high band sharing coefficients, low heterozygosity and high inbreeding coefficients in phylogenetic analyses after controlling statistically for potentially confounding variables. These findings imply that anti-predator behavior is related to genetic variance. We predict that many threatened species with low genetic variability will show reduced anti-predator behavior, and that subsequent predator-induced reductions in abundance may contribute to unfavorable population trends for such species.

捕食是众多生物常见的致死原因，由此演化出了诸多反捕食防御策略。此类防御策略往往具有遗传基础，显著的遗传力以及无捕食者环境下防御能力弱化的微进化响应，均可佐证这一点。惊飞距离（Flight Initiation Distance, FID）指单个动物在人类靠近时起飞逃逸的距离，因此它反映了捕食风险与觅食收益之间的生活史权衡。本研究针对128种鸟类的惊飞距离，结合三项遗传变异指标——小卫星DNA的条带共享系数、微卫星DNA的观测杂合度与近交系数——展开分析，以检验惊飞距离是否与遗传变异呈正相关。在系统发育分析中，我们在控制潜在混淆变量后发现：当条带共享系数较高、杂合度较低且近交系数较高时，对应体型下的惊飞距离普遍更短。上述结果表明，反捕食行为与遗传变异程度密切相关。我们据此预测，诸多遗传变异水平较低的受威胁物种，其反捕食行为能力会出现下降；而后续由捕食者驱动的种群数量缩减，可能会进一步加剧这类物种的种群衰退趋势。