Most populations of giraffes have declined in recent decades, leading to the recent IUCN decision to upgrade the species to Vulnerable status, and some subspecies to Endangered. Translocations have been used as a conservation tool to re-introduce giraffes to previously occupied areas or establish new populations, but guidelines for founding populations are lacking. To provide general guidelines for translocation projects regarding feasibility, we simulated various scenarios of translocated giraffe populations to identify viable age and sex distributions of founding populations using population viability analysis (PVA) implemented in Vortex software. We explored the parameter space for demography and the genetic load, examining how variation in founding numbers and sex ratios affected 100 yr probability of population extinction and genetic diversity. We found that even very small numbers of founders (N ≤ 10 females) can appear to be successful in the first decades due to transient positive population growth, but with moderate population growth rate and moderate genetic load, long-term population viability (probability of extinction 95% genetic diversity of the source population in an isolated population, 50 females and 5 males are recommended to compose the founding population. Sensitivity analyses revealed first-year survival and reproductive rate were the simulation parameters with the greatest proportional influence on probability of extinction and genetic diversity. These simulations highlight important considerations for translocation success and data gaps including true genetic load in wild giraffe populations.

中文翻译：

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长颈鹿易位种群生存力分析

近几十年来，大多数长颈鹿种群数量下降，导致最近 IUCN 决定将该物种升级为易危物种，并将一些亚种升级为濒危物种。易位已被用作保护工具，将长颈鹿重新引入以前占领的地区或建立新的种群，但缺乏建立种群的指导方针。为了为易地项目的可行性提供一般指导，我们模拟了易地长颈鹿种群的各种场景，以使用 Vortex 软件中实施的种群生存力分析 (PVA) 来确定创始种群的可行年龄和性别分布。我们探索了人口统计学和遗传负荷的参数空间，检查创始人数和性别比例的变化如何影响人口灭绝和遗传多样性的 100 年概率。我们发现，即使是极少数的创始人（N ≤ 10 名女性），由于短暂的人口正增长，在最初的几十年中似乎也能取得成功，但人口增长率适中，遗传负荷适中，长期人口生存能力（概率为灭绝 孤立种群中源种群的 95% 遗传多样性，建议 50 只雌性和 5 只雄性组成创始种群。敏感性分析显示，第一年存活率和繁殖率是对灭绝概率成比例影响最大的模拟参数和遗传多样性。