Pedigree analysis reveals a generational decline in reproductive success of captive Tasmanian devil (Sarcophilus harrisii): implications for captive management of threatened species

Captive breeding programs are an increasingly popular tool to augment the conservation of threatened wild populations. Many programs keep detailed pedigrees, which are used to prescribe breeding targets to meet demographic and genetic goals. Annual breeding targets are based on previous productivity, but do not account for changes in reproductive success that may occur over generations in captivity and which may impair the ability of a program to meet its goals. We utilise a large studbook from the Tasmanian devil (Sarcophilus harrisii) captive breeding program to investigate biological, genetic and environmental factors that affect variation in reproductive success among individuals and over generations of captive breeding. Reproductive success declined with increasing generations in captivity: wild-born females had a 56.5% chance of producing a litter compared to a 2.8% chance for generation 5 captive-born females (N = 182) and when they did, wild-born females produced more offspring ...圈养繁育计划已逐渐成为辅助濒危野生种群保护的重要手段。多数繁育项目会留存详尽的个体谱系档案，以此制定繁育目标以达成种群统计学与遗传学保护目标。当前的年度繁育目标多基于过往繁育产出率制定，但未考虑圈养多代繁育过程中繁殖成功率可能发生的变化，而此类变化或会削弱项目达成既定目标的能力。本研究依托袋獾（Sarcophilus harrisii）圈养繁育计划的大型繁育档案册，探究影响个体间及圈养多代繁育过程中繁殖成功率差异的生物、遗传与环境因素。研究结果显示，繁殖成功率随圈养世代增加呈下降趋势：野生起源的雌性个体产仔概率为56.5%，而第5代圈养起源的雌性个体产仔概率仅为2.8%（样本量N=182）；即便成功产仔，野生起源的雌性个体所产幼崽数量也更多……