Ellwanger Claire, Steger Laura, Pollack Cathy, Wells Rachel, Benjamin Fant Jeremie
Plant Biology and Conservation Chicago Botanic Garden Glencoe Illinois USA.
Plant Biology and Conservation Northwestern University, O.T. Hogan Hall Evanston Illinois USA.
Ecol Evol. 2022 Feb 17;12(2):e8578. doi: 10.1002/ece3.8578. eCollection 2022 Feb.
Protecting biodiversity requires an understanding of how anthropogenic changes impact the genetic processes associated with extinction risk. Studies of the genetic changes due to anthropogenic fragmentation have revealed conflicting results. This is likely due to the difficulty in isolating habitat loss and fragmentation, which can have opposing impacts on genetic parameters. The well-studied orchid, , provides a rich dataset to address this issue, allowing us to examine range-wide genetic changes. Midwestern and Northeastern United States. We sampled 35 populations of that spanned the species' range and varied in patch composition, degree of patch isolation, and population size. From these populations we measured genetic parameters associated with increased extinction risk. Using this combined dataset, we modeled landscape variables and population metrics against genetic parameters to determine the best predictors of increased extinction risk. All genetic parameters were strongly associated with population size, while development and patch isolation showed an association with genetic diversity and genetic structure. Genetic diversity was lowest in populations with small census sizes, greater urbanization pressures (habitat loss), and small patch area. All populations showed moderate levels of inbreeding, regardless of size. Contrary to expectation, we found that critically small populations had negative inbreeding values, indicating non-random mating not typically observed in wild populations, which we attribute to selection for less inbred individuals. The once widespread orchid, , has suffered drastic declines and extant populations show changes in the genetic parameters associated with increased extinction risk, especially smaller populations. Due to the important correlation with risk and habitat loss, we advocate continued monitoring of population sizes by resource managers, while the critically small populations may need additional management to reverse genetic declines.
保护生物多样性需要了解人为变化如何影响与灭绝风险相关的遗传过程。对人为造成的碎片化所导致的遗传变化的研究结果相互矛盾。这可能是由于难以区分栖息地丧失和碎片化，它们对遗传参数可能产生相反的影响。经过充分研究的兰花（此处原文未提及兰花具体名称）提供了丰富的数据集来解决这个问题，使我们能够研究整个分布范围内的遗传变化。美国中西部和东北部。我们对跨越该物种分布范围、斑块组成、斑块隔离程度和种群大小各异的35个种群进行了采样。从这些种群中，我们测量了与灭绝风险增加相关的遗传参数。利用这个综合数据集，我们将景观变量和种群指标与遗传参数进行建模，以确定灭绝风险增加的最佳预测因子。所有遗传参数都与种群大小密切相关，而开发活动和斑块隔离与遗传多样性和遗传结构存在关联。在普查规模小、城市化压力大（栖息地丧失）以及斑块面积小的种群中，遗传多样性最低。所有种群都表现出中等程度的近亲繁殖，无论种群大小如何。与预期相反，我们发现极小的种群具有负的近亲繁殖值，这表明在野生种群中通常未观察到的非随机交配，我们将其归因于对近亲繁殖程度较低个体的选择。曾经广泛分布的兰花（此处原文未提及兰花具体名称）数量急剧下降，现存种群显示出与灭绝风险增加相关的遗传参数变化，尤其是较小的种群。由于与风险和栖息地丧失的重要相关性，我们主张资源管理者持续监测种群大小，而极小的种群可能需要额外的管理措施来扭转遗传衰退。
