Conservation translocation is a common strategy to offset mounting rates of population declines through the transfer of captive- or wild-origin organisms into areas where conspecific populations are imperilled or completely extirpated. Translocations that supplement existing populations are referred to as reinforcements and can be conducted using captive-origin animals [ex situ reinforcement (ESR)] or wild-origin animals without any captive ancestry [in situ reinforcement (ISR)]. These programs have been criticized for low success rates and husbandry practices that produce individuals with genetic and performance deficits, but the post-release performance of captive-origin or wild-origin translocated groups has not been systematically reviewed to quantify success relative to wild-resident control groups. To assess the disparity in post-release performance of translocated organisms relative to wild-resident conspecifics and examine the association of performance disparity with organismal and methodological factors across studies, we conducted a systematic review and meta-analysis of 821 performance comparisons from 171 studies representing nine animal classes (101 species). We found that translocated organisms have 64% decreased odds of out-performing their wild-resident counterparts, supporting claims of systemic issues hampering conservation translocations. To help identify translocation practices that could maximize program success in the future, we further quantified the impact of broad organismal and methodological factors on the disparity between translocated and wild-resident conspecific performance. Pre-release animal enrichment significantly reduced performance disparities, whereas our results suggest no overall effects of taxonomic group, sex, captive generation time, or the type of fitness surrogate measured. This work is the most comprehensive systematic review to date of animal conservation translocations in which wild conspecifics were used as comparators, thereby facilitating an evaluation of the overall impact of this conservation strategy and identifying specific actions to increase success. Our review highlights the need for conservation managers to include both sympatric and allopatric wild-reference groups to ensure the post-release performance of translocated animals can be evaluated. Further, our analyses identify pre-release animal enrichment as a particular strategy for improving the outcomes of animal conservation translocations, and demonstrate how meta-analysis can be used to identify implementation choices that maximize translocated animal contributions to recipient population growth and viability.

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野生动物保护易地的适应性后果：荟萃分析

保护易地是一种常见的策略，通过将圈养或野生来源的生物转移到同种种群受到威胁或完全灭绝的地区来抵消种群数量不断减少的速度。补充现有种群的易位被称为强化，可以使用圈养动物[异位强化（ESR）]或没有任何圈养祖先的野生动物[原位强化（ISR）]进行。这些计划因成功率低和产生具有遗传和性能缺陷的个体的饲养方法而受到批评，但圈养来源或野生来源易位群体的释放后表现尚未经过系统审查，以量化相对于野生居民的成功率对照组。为了评估易地生物相对于野生同种动物的放归后性能差异，并检查研究中性能差异与有机体和方法学因素之间的关系，我们对来自 171 项研究的 821 项性能比较进行了系统回顾和荟萃分析，这些研究代表了九个动物纲（101 种）。我们发现，易地生物的表现优于野生生物的几率降低了 64%，这支持了阻碍保护性易地的系统性问题的说法。为了帮助确定未来能够最大限度地提高计划成功率的易位实践，我们进一步量化了广泛的有机和方法因素对易位和野生居民同种表现之间差异的影响。释放前的动物富集显着减少了性能差异，而我们的结果表明分类群、性别、圈养世代时间或测量的适应性替代类型没有总体影响。这项工作是迄今为止对动物保护易地最全面的系统回顾，其中野生同种动物被用作比较，从而有助于评估该保护策略的总体影响并确定提高成功率的具体行动。我们的审查强调，保护管理者需要将同域和异域野生参考群体纳入其中，以确保可以评估易地动物的释放后表现。此外，我们的分析将释放前动物富集确定为改善动物保护易地结果的特殊策略，并展示了如何使用荟萃分析来确定实施选择，以最大限度地提高易地动物对受体种群增长和生存能力的贡献。