U.S. Geological Survey, Western Ecological Research Center, Santa Cruz, California, United States of America.
U.S. Geological Survey, Western Ecological Research Center, Dixon, California, United States of America.
PLoS One. 2023 Oct 5;18(10):e0292379. doi: 10.1371/journal.pone.0292379. eCollection 2023.
For endangered species persisting in a few populations, reintroductions to unoccupied habitat are a popular conservation action to increase viability in the long term. Identifying the reintroduction strategy that is most likely to result in viable founder and donor populations is essential to optimally use resources available for conservation. The San Francisco gartersnake (Thamnophis sirtalis tetrataenia) is an endangered sub-species that persists in a small number of populations in a highly urbanized region of California. Most of the extant populations of San Francisco gartersnakes have low adult abundance and effective population size, heightening the need for establishment of more populations for insurance against the risk of extinction. We used simulations from demographic models to project the probability of quasi-extinction for reintroduced populations of San Francisco gartersnakes based on the release of neonate, juvenile, adult, or mixed-age propagules. Our simulation results indicated that the release of head-started juveniles resulted in the greatest viability of reintroduced populations, and that releases would need to continue for at least 15 years to ensure a low probability of quasi-extinction. Releasing captive-bred juvenile snakes would also have less effect on the viability of the donor population, compared to strategies that require more adult snakes to be removed from the donor population for translocation. Our models focus on snake demography, but the genetic makeup of donor, captive, and reintroduced populations will also be a major concern for any proposed reintroduction plan. This study demonstrates how modeling can be used to inform reintroduction strategies for highly imperiled species.
对于那些仅在少数几个种群中生存的濒危物种，重新引入未占据的栖息地是一种常见的保护行动，可从长远角度提高其生存能力。确定最有可能导致可行的创始种群和供体种群的重新引入策略对于优化可用资源用于保护至关重要。旧金山束带蛇（Thamnophis sirtalis tetrataenia）是一种濒危亚种，仅在加利福尼亚高度城市化地区的少数几个种群中生存。旧金山束带蛇现存的大多数种群其成年个体数量和有效种群数量都较少，这增加了建立更多种群的必要性，以防止灭绝风险。我们使用基于个体的模型中的模拟来预测旧金山束带蛇重新引入种群的准灭绝概率，这些模拟基于释放幼体、幼体、成体或混合年龄的繁殖体。我们的模拟结果表明，释放经过提前孵化的幼体可使重新引入的种群具有最大的生存能力，并且至少需要持续释放 15 年才能确保准灭绝的概率较低。与需要从供体种群中移走更多成体蛇用于转移的策略相比，释放圈养繁殖的幼蛇对供体种群的生存能力影响较小。我们的模型主要关注蛇的种群动态，但供体、圈养和重新引入种群的遗传组成也将是任何拟议的重新引入计划的主要关注点。本研究展示了如何利用建模来为高度濒危物种的重新引入策略提供信息。
