Abstract

Island populations are hallmarks of extreme phenotypic evolution. Radical changes in resource availability and predation risk accompanying island colonization drive changes in behavior, which Darwin likened to tameness in domesticated animals. Although many examples of animal boldness are found on islands, the heritability of observed behaviors, a requirement for evolution, remains largely unknown. To fill this gap, we profiled anxiety and exploration in island and mainland inbred strains of house mice raised in a common laboratory environment. The island strain was descended from mice on Gough Island, the largest wild house mice on record. Experiments utilizing open environments across two ages showed that Gough Island mice are bolder and more exploratory, even when a shelter is provided. Concurrently, Gough Island mice retain an avoidance response to predator urine. F1 offspring from crosses between these two strains behave more similarly to the mainland strain for most traits, suggesting recessive mutations contributed to behavioral evolution on the island. Our results provide a rare example of novel, inherited behaviors in an island population and demonstrate that behavioral evolution can be specific to different forms of perceived danger. Our discoveries pave the way for a genetic understanding of how island populations evolve unusual behaviors.

Significance

Organisms on islands are known to behave differently from mainland organisms. An absence of predators and a different set of natural resources are expected to make island organisms less anxious and more exploratory. We raised two groups of house mice, one from Gough Island in the South Atlantic and one from the mainland Eastern USA, in the same laboratory environment to see if behavioral differences between the two groups are heritable. Mice from both groups were placed in novel enclosures that are known to cause anxiety in rodents. We found that mice from the island are bolder and more exploratory in these enclosures but avoid predator odors in the same way as mainland mice. Our results show that boldness and exploration can evolve after island colonization.

中文翻译：

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戈夫岛巨鼠胆量和探索行为的演变

摘要

岛屿种群是极端表型进化的标志。伴随岛屿殖民化而来的资源可用性和捕食风险的根本变化推动了行为的变化，达尔文将其比作家养动物的驯服。尽管在岛屿上发现了许多动物大胆的例子，但观察到的行为的遗传性（进化的要求）在很大程度上仍然未知。为了填补这一空白，我们描述了在普通实验室环境中饲养的岛屿和大陆近交家鼠品系的焦虑和探索。岛上的品系是戈夫岛上老鼠的后代，这是有记录以来最大的野生家鼠。利用跨越两个年龄段的开放环境进行的实验表明，高夫岛小鼠更大胆、更具探索性，即使在提供庇护所的情况下也是如此。同时，戈夫岛老鼠对捕食者的尿液保持回避反应。这两个菌株杂交产生的 F1 后代在大多数性状上与大陆菌株的行为更相似，这表明隐性突变促成了岛上的行为进化。我们的研究结果提供了一个罕见的岛屿人口新奇遗传行为的例子，并证明行为进化可以特定于不同形式的感知危险。我们的发现为从遗传学上理解岛屿种群如何演化出异常行为铺平了道路。岛上人口的遗传行为，并证明行为进化可以特定于不同形式的感知危险。我们的发现为从遗传学上理解岛屿种群如何演化出异常行为铺平了道路。岛上人口的遗传行为，并证明行为进化可以特定于不同形式的感知危险。我们的发现为从遗传学上理解岛屿种群如何演化出异常行为铺平了道路。

意义

众所周知，岛屿上的生物与大陆生物的行为不同。没有捕食者和一组不同的自然资源预计将使岛屿生物不那么焦虑，更具探索性。我们在同一实验室环境中饲养了两组家鼠，一组来自南大西洋的戈夫岛，一组来自美国东部大陆，以观察两组之间的行为差​​异是否可遗传。两组小鼠都被安置在已知会引起啮齿动物焦虑的新型围栏中。我们发现，岛上的老鼠在这些围栏中更大胆、更具探索性，但与大陆老鼠一样，它们也会避开捕食者的气味。我们的结果表明，大胆和探索可以在岛屿殖民化后进化。