Data from: Experimental test of genetic rescue in isolated populations of brook trout

Genetic rescue is an increasingly considered conservation measure to address genetic erosion associated with habitat loss and fragmentation. The resulting gene flow from facilitating migration may improve fitness and adaptive potential, but is not without risks (e.g., outbreeding depression). Here, we conducted a test of genetic rescue by translocating ten (five of each sex) brook trout (Salvelinus fontinalis) from a single source to four nearby and isolated stream populations. To control for the demographic contribution of translocated individuals, ten resident individuals (five of each sex) were removed from each recipient population. Prior to the introduction of translocated individuals, the two smallest above-barrier populations had substantially lower genetic diversity, and all populations had reduced effective number of breeders relative to adjacent below-barrier populations. In the first reproductive bout following translocation, 31 of 40 (78%) translocated individuals reproduced successfully. Translocated individuals contributed to more families than expected under random mating and generally produced larger full-sibling families. We observed relatively high (>20%) introgression in three of the four recipient populations. The translocations increased genetic diversity of recipient populations by 45% in allelic richness and 25% in expected heterozygosity. Additionally, strong evidence of hybrid vigour was observed through significantly larger body sizes of hybrid offspring relative to resident offspring in all recipient populations. Continued monitoring of these populations will test for negative fitness effects beyond the first generation. However, these results provide much-needed experimental data to inform the potential effectiveness of genetic rescue-motivated translocations.

遗传拯救（Genetic rescue）是一种日益受到重视的保护措施，用以应对与生境丧失和破碎化相关的遗传侵蚀（genetic erosion）。由此通过促进个体迁移产生的基因流可提升种群适合度与适应性潜力，但也并非全无风险（例如远交衰退（outbreeding depression））。本研究通过将10尾溪鳟（Salvelinus fontinalis，雌雄各5尾）从单一源种群转移至4个邻近且隔离的溪流种群，开展了遗传拯救的实验验证。为控制移殖个体对接收种群的种群统计贡献，我们从每个接收种群中移除了10尾本土个体（雌雄各5尾）。在移殖个体引入前，两个位于屏障上方的最小种群的遗传多样性显著更低，且相较于邻近的屏障下方种群，所有接收种群的有效繁殖种群数量均有所下降。在移殖后的首个繁殖季中，40尾移殖个体中有31尾（78%）成功繁殖。移殖个体参与繁殖的家系数量多于随机交配下的预期值，且通常能产生更大的全同胞家系。我们在4个接收种群中的3个种群内观察到了较高（>20%）的基因渐渗（introgression）现象。此次移殖使接收种群的遗传多样性得到提升：等位基因丰富度（allelic richness）提升45%，期望杂合度（expected heterozygosity）提升25%。此外，所有接收种群的杂交后代体型均显著大于本土后代，这为杂种优势（hybrid vigour）提供了强有力的证据。对这些种群的持续监测将用于检验后续世代中是否存在负面适合度效应。尽管如此，本研究结果为旨在开展遗传拯救的种群移殖措施的潜在有效性提供了亟需的实验数据支撑。