Data from: Captive ancestry upwardly biases estimates of relative reproductive success

Supplementation programs, which release captive-born individuals into the wild, are commonly used to demographically bolster declining populations. In order to evaluate the effectiveness of these programs, the reproductive success of captive-born individuals released into the wild is often compared to the reproductive success of wild-born individuals in the recipient population (relative reproductive success, RRS). However, if there are heritable reductions in fitness associated with captive breeding, gene flow from captive-born individuals into the wild population can reduce the fitness of the wild population. Here, we show that when captive ancestry in the wild population reduces mean population fitness, estimates of RRS are upwardly biased, meaning that the relative fitness of captive-born individuals is over-estimated. Furthermore, the magnitude of this bias increases with the length of time that a supplementation program has been releasing captive-born individuals. This phenomenon has long-term conservation impacts since management decisions regarding the design of a supplementation program and the number of individuals to release can be based, at least in part, on RRS estimates. Therefore, we urge caution in the interpretation of relative fitness measures when the captive ancestry of the wild population cannot be precisely measured.

将圈养繁育个体放归野外的种群补充计划，常被用于从种群统计学层面助力衰退种群的恢复。为评估这类计划的实施效果，研究人员通常会将放归野外的圈养个体的繁殖成功率，与接收种群内野生个体的繁殖成功率进行比较，即相对繁殖成功率（relative reproductive success, RRS）。然而，若圈养繁育会引发适合度的可遗传降低，那么圈养个体向野生种群的基因流便会降低野生种群的整体适合度。本研究证实，当野生种群中的圈养祖先血统降低了种群平均适合度时，相对繁殖成功率的估算结果会出现正向偏倚，即圈养个体的相对适合度被高估。进一步而言，这类偏倚的程度会随着种群补充计划放归圈养个体的时长增加而加剧。这一现象会产生长期的保护效应，因为种群补充计划的设计方案、拟放归个体数量等管理决策，至少会部分依赖于相对繁殖成功率的估算结果。因此，当无法精准测定野生种群的圈养祖先血统时，我们呼吁在解读相对适合度指标时保持审慎态度。