Department of Ecology and Evolutionary Biology, University of California Los Angeles, Los Angeles, CA, USA.
Santa Monica Mountains National Recreation Area, National Park Service, 401 West Hillcrest Drive, Thousand Oaks, CA, 91360, USA.
Theriogenology. 2022 Jan 1;177:157-164. doi: 10.1016/j.theriogenology.2021.10.016. Epub 2021 Oct 19.
Long-term studies of mountain lions (Puma concolor) in Southern California have documented persistent small population sizes and the lowest genetic variation of any mountain lion population, except for the Federally endangered mountain lion subspecies, the Florida panther (Puma concolor coryi). There is overwhelming molecular evidence supporting inbreeding and low genetic diversity in these Southern California populations but there is a lack of phenotypical evidence of inbreeding depression. The primary goal of this study was to assess male mountain lions, in Southern California, for teratospermia (>60% abnormal sperm production), one of the first signs of inbreeding depression in mountain lions that are associated with decreased reproduction and population decline. From December 2019 to December 2020, we surveyed mountain lions during live captures, after mortality events, and in images collected from camera traps in the following populations: Santa Monica Mountains, Santa Susana Mountains, Santa Ana Mountains, and the Eastern Peninsular Range. Mountain lions were sampled for known physical abnormalities associated with inbreeding depression such as teratospermia, cryptorchidism, and distal tail kinks. For teratospermia, we extracted testes from five males post-mortem to assess sperm morphology. Epididymal sperm evaluations revealed all males were teratospermic. Across all samples, on average, 93% of observed spermatozoa were abnormal. We physically examined 32 mountain lions (males and females) for distal tail kinks, and we observed one individual affected. We examined 15 male mountain lions for cryptorchidism, and we observed one unilaterally cryptorchid male and one male with testes that differed significantly in size, likely reflecting asynchronous migration of the testes during puberty. Further, we identified three other animals in camera-trap images that had distal tail kinks, for a total of four. In conclusion, from December 2019 to December 2020, we identified nine individuals exhibiting physical signs of inbreeding depression. These reproductive and physical signs of inbreeding depression in Southern California mountain lions increase the urgency of conservation efforts in the region.
对南加州山狮（Puma concolor）的长期研究记录表明，其种群规模一直较小，遗传变异率在所有山狮种群中最低，除了联邦濒危的佛罗里达美洲狮亚种（Puma concolor coryi）。有压倒性的分子证据支持这些南加州山狮种群存在近亲繁殖和遗传多样性低的情况，但缺乏近亲繁殖衰退的表型证据。本研究的主要目标是评估南加州的雄性山狮是否存在畸形精子症（>60%的精子异常产生），这是山狮近亲繁殖衰退的最初迹象之一，与繁殖力下降和种群减少有关。2019 年 12 月至 2020 年 12 月，我们在以下种群中通过活体捕获、死亡事件后和从相机陷阱收集的图像对山狮进行了调查：圣莫尼卡山脉、圣苏珊娜山脉、圣安娜山脉和东半岛山脉。我们对山狮进行了采样，以评估与近亲繁殖衰退相关的已知身体异常，如畸形精子症、隐睾症和尾部末端卷曲。对于畸形精子症，我们从五头死后的雄性山狮中提取睾丸来评估精子形态。附睾精子评估显示所有雄性山狮都患有畸形精子症。在所有样本中，平均 93%的观察到的精子异常。我们对 32 只山狮（雄性和雌性）进行了尾部末端卷曲的物理检查，发现一只个体受影响。我们检查了 15 只雄性山狮的隐睾症，发现一只单侧隐睾雄性和一只睾丸大小明显不同的雄性，可能反映了青春期睾丸的不同步迁移。此外，我们在相机陷阱图像中还发现了另外三只尾部末端卷曲的动物，总共有四只。总之，2019 年 12 月至 2020 年 12 月，我们发现了 9 只表现出近亲繁殖衰退的身体异常的个体。南加州山狮的这些繁殖和身体上的近亲繁殖衰退迹象增加了该地区保护工作的紧迫性。
