Data from: A single migrant enhances the genetic diversity of an inbred puma population

Migration is essential for maintaining genetic diversity among populations, and pumas (Puma concolor) provide an excellent model for studying the genetic impacts of migrants on populations isolated by increasing human development. In densely-populated southern California, USA, puma populations on the east and west side of interstate highway 15 (I-15) have become fragmented into a small inbred population on the west side (Santa Ana Mountains) and a relatively larger, more diverse population on the east side (Eastern Peninsular Range). From 146 sampled pumas, genetic analyses indicate 7 pumas crossed I-15 over the last 15 years, including four males from west to east, and three males from east to west. However, only a single migrant (named M86) was detected to have produced offspring and contribute to gene flow across the I-15 barrier. Prior to the M86 migration, the Santa Ana population exhibited inbreeding and had significantly lower genetic diversity than the Eastern Peninsular Range population. After M86 emigrated, he sired 11 offspring with Santa Ana females, decreasing inbreeding measures and raising heterozygosity to levels similar to pumas in the Eastern Peninsular Range. The emigration of M86 also introduced new alleles into the Santa Ana population, although allelic richness still remained significantly lower than the Eastern Peninsular population. Our results clearly show the benefit of a single migrant to the genetics of a small, isolated population. However, ongoing development and habitat loss on both sides of I-15 will increasingly strengthen the barrier to successful migration. Further monitoring, and potential human intervention, including minimizing development effects on connectivity, adding or improving freeway crossing structures, or animal translocation, may be needed to ensure adequate gene flow and long-term persistence of the Santa Ana puma population.种群迁徙对维持种群间遗传多样性至关重要，美洲狮（Puma concolor）是研究人类开发加剧导致种群隔离后，迁徙个体对种群遗传特征影响的极佳模型物种。在美国人口稠密的南加州，15号州际公路（I-15）东西两侧的美洲狮种群已被隔离分化为两类：西侧圣安娜山脉的小型近交种群，以及东侧半岛山脉的规模更大、遗传多样性更丰富的种群。本研究对146只采样美洲狮开展遗传分析，结果显示过去15年间共有7只个体成功跨越I-15屏障，其中4只为西向东部迁徙的雄性个体，3只为东向西部迁徙的雄性个体。但仅有一只被命名为M86的迁徙个体，成功繁衍后代并为I-15两侧的基因流做出了贡献。在M86迁徙入驻前，圣安娜种群存在明显的近交现象，其遗传多样性显著低于半岛山脉种群。M86迁入后，与圣安娜种群的雌性美洲狮共育有11只后代，有效降低了种群近交程度，并将群体杂合度提升至与半岛山脉种群相近的水平。尽管圣安娜种群的等位基因丰富度仍显著低于半岛山脉种群，但M86的迁入也为该种群引入了新的等位基因。本研究结果清晰证实了单只迁徙个体对小型隔离种群遗传健康的积极作用。然而，I-15两侧持续进行的开发活动与栖息地丧失，将不断强化这一迁徙屏障的阻隔效应。为保障足够的基因流并维持圣安娜美洲狮种群的长期存续，后续需开展持续监测，并视情况采取人类干预措施——包括降低开发活动对种群连通性的影响、增设或改进跨高速路的野生动物通道，或是实施动物易地保护等。