Extinction vortex dynamics of top predators isolated by urbanization
Extinction vortex dynamics of top predators isolated by urbanization
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DOI：
10.1002/eap.1868
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发表时间：
2019-04-01
影响因子：
5
通讯作者：
Boyce, Walter M.
中科院分区：
文献类型：
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作者：
Benson, John F.;Mahoney, Peter J.;Boyce, Walter M.
由于人口统计学和遗传学的相互作用，灭绝风险在小的、孤立的种群中升高。因此，在种群生存分析（PVA）中对这些过程进行逼真的建模是至关重要的，以便为当地管理提供信息，并有助于更好地了解灭绝涡旋内的机制。我们进行了PVA的两个小的山狮种群隔离的城市化在南加州预测人口增长，灭绝概率，和遗传多样性的损失与经验数据。具体来说，我们（1）提供了第一个PVA孤立的山狮在圣安娜山脉（SAM），同时考虑人口和遗传风险因素和（2）测试的假设，丰富的变化和死亡率之间的SAM和圣莫尼卡山脉（SMM）的结果在人口增长，杂合性丢失和灭绝概率的差异。我们的模型预测，由于纯粹的人口过程超过50年，目前的低水平或没有移民的SAM的本地灭绝的概率为16-21%。我们的模型还预测，遗传多样性将进一步侵蚀SAM，除非基因流增加，否则对近亲繁殖衰退的担忧是有道理的，如果发生近亲繁殖衰退，快速局部灭绝的可能性很大。两个种群的动态大致相似，但它们也表现出较大的种群规模和较高的死亡率在SAM驱动的差异。密度无关的情况下，预测在SMM人口迅速增加，而增长潜力并没有从SAM的稳定趋势不同。人口灭绝概率和杂合性丢失更大的SMM密度依赖的情况下，没有移民。然而，更高水平的移民有更强的，积极的影响，人口的生存能力和保留的遗传多样性在SMM驱动的丰度较低和较高的成人生存。我们的研究结果阐明了灭绝漩涡中小种群的人口和遗传威胁，以及这些威胁相对于人口结构如何变化。重要的是，模拟似乎可以实现的连通性增加足以大大降低灭绝概率。我们的工作强调，大型食肉动物的保护是可以实现的城市化景观，但需要土地保护，连通性和战略，以促进与人类共存。
Extinction risk is elevated in small, isolated populations due to demographic and genetic interactions. Therefore, it is critical to model these processes realistically in population viability analyses (PVA) to inform local management and contribute to a greater understanding of mechanisms within the extinction vortex. We conducted PVA's for two small mountain lion populations isolated by urbanization in southern California to predict population growth, extinction probability, and loss of genetic diversity with empirical data. Specifically, we (1) provide the first PVA for isolated mountain lions in the Santa Ana Mountains (SAM) that considers both demographic and genetic risk factors and (2) test the hypothesis that variation in abundance and mortality between the SAM and Santa Monica Mountains (SMM) result in differences in population growth, loss of heterozygosity, and extinction probability. Our models predicted 16-21% probability of local extinction in the SAM due purely to demographic processes over 50 yr with current low levels or no immigration. Our models also predicted that genetic diversity will further erode in the SAM such that concern regarding inbreeding depression is warranted unless gene flow is increased, and that if inbreeding depression occurs, rapid local extinction will be highly likely. Dynamics of the two populations were broadly similar, but they also exhibited differences driven by larger population size and higher mortality in the SAM. Density-independent scenarios predicted a rapidly increasing population in the SMM, whereas growth potential did not differ from a stable trend in the SAM. Demographic extinction probability and loss of heterozygosity were greater in the SMM for density-dependent scenarios without immigration. However, higher levels of immigration had stronger, positive influences on both demographic viability and retention of genetic diversity in the SMM driven by lower abundance and higher adult survival. Our results elucidate demographic and genetic threats to small populations within the extinction vortex, and how these vary relative to demographic structure. importantly, simulating seemingly attainable increases in connectivity was sufficient to greatly reduce extinction probability. Our work highlights that conservation of large carnivores is achievable within urbanized landscapes, but requires land protection, connectivity, and strategies to promote coexistence with humans.