Data_Sheet_1_Genetic Insights Into the Introduction History of Black Rats Into the Eastern Indian Ocean.pdf

Islands can be powerful demonstrations of how destructive invasive species can be on endemic faunas and insular ecologies. Oceanic islands in the eastern Indian Ocean have suffered dramatically from the impact of one of the world’s most destructive invasive species, the black rat, causing the loss of endemic terrestrial mammals and ongoing threats to ground-nesting birds. We use molecular genetic methods on both ancient and modern samples to establish the origins and minimum invasion frequencies of black rats on Christmas Island and the Cocos-Keeling Islands. We find that each island group had multiple incursions of black rats from diverse geographic and phylogenetic sources. Furthermore, contemporary black rat populations on these islands are highly admixed to the point of potentially obscuring their geographic sources. These hybridisation events between black rat taxa also pose potential dangers to human populations on the islands from novel disease risks. Threats of ongoing introductions from yet additional geographic sources is highlighted by genetic identifications of black rats found on ships, which provides insight into how recent ship-borne human smuggling activity to Christmas Island can negatively impact its endemic species.

岛屿是阐释入侵物种对特有动物区系与岛屿生态系统破坏性的绝佳实证案例。东印度洋的大洋性岛屿遭受了全球破坏性最强的入侵物种之一——黑家鼠（black rat）的严重冲击，造成当地特有陆生哺乳动物灭绝，并持续威胁地面筑巢鸟类的生存。本研究通过古代与现代样本结合的分子遗传学方法，明确了圣诞岛与科科斯（基林）群岛上黑家鼠的起源与最低入侵频次。研究结果显示，两个群岛的黑家鼠均存在多起源自不同地理与系统发育背景的入侵事件。此外，这些岛屿上的当代黑家鼠种群高度遗传混杂，其地理来源已难以通过现有数据追溯。黑家鼠不同类群间的杂交事件，还可能通过新型疾病传播风险，对岛上人类群体构成潜在威胁。对船上发现的黑家鼠开展的遗传鉴定，进一步凸显了额外地理来源物种持续引入的威胁；该研究结果也揭示了近期经海路偷渡至圣诞岛的人类活动，如何对该岛特有物种造成负面影响。