Dietary morphology of two island-endemic murine rodent clades is consistent with persistent, incumbent-imposed competitive interactions

A lineage colonizing a geographic region with no competitors may exhibit rapid diversification due to greater ecological opportunity. The resultant species diversity of this primary-colonizing (incumbent) clade may limit subsequent lineages’ ability to persist unless these non-incumbent lineages are ecologically distinct. We compare the diversity in diet-related mandibular morphology of two sympatric murid rodent clades endemic to Luzon Island, Philippines—incumbent Phloeomyini and secondary-colonizing Chrotomyini—to the mandibular morphological diversity of Sahul Hydromyini, the sister clade of Chrotomyini and the incumbent murid lineage on the supercontinent of Sahul. This three-clade comparison allows us to test the hypothesis that incumbent lineages can force persistent ecological distinction of subsequent colonists at the time of colonization and throughout the subsequent history of the two sympatric clades. We find that Chrotomyini forms a subset of the diversity of their clade pl...

当一个演化世系（lineage）入侵无竞争者的地理区域时，依托更充足的生态机遇，可能会经历快速的物种分化。这类初始定植的原驻（incumbent）演化支所形成的物种多样性，往往会限制后续世系的存续能力，除非这些非原驻世系具备独特的生态位特征。我们以菲律宾吕宋岛的两类同域分布、特有分布的鼠科（Muridae）啮齿类演化支——原驻的硬毛鼠族（Phloeomyini）与次生定植的澳洲原鼠族（Chrotomyini）——的食性相关下颌形态多样性为研究对象，并与萨赫勒超大陆（Sahul）上的优势鼠科世系、同时也是澳洲原鼠族姊妹演化支的萨赫勒原鼠族（Hydromyini）的下颌形态多样性开展对比分析。通过这三类演化支的比较研究，我们得以检验如下假说：原驻世系可在定植发生之时，以及后续两类同域演化支的整个演化历史中，迫使后续定植类群形成稳定的生态位分化。本研究发现，澳洲原鼠族（Chrotomyini）的形态多样性仅为其所在演化支多样性的一个子集……