Data from: How do seemingly non-vagile clades accomplish trans-marine dispersal? Trait and dispersal evolution in the landfowl (Aves: Galliformes)

Dispersal ability is a key factor in determining insular distributions and island community composition, yet non-vagile terrestrial organisms widely occur on oceanic islands. The landfowl (pheasants, partridges, grouse, turkeys, quails and relatives) are generally poor dispersers, but the Old World quail (Coturnix) are a notable exception. These birds evolved small body sizes and high-aspect-ratio wing shapes, and hence are capable of trans-continental migrations and trans-oceanic colonization. Two monotypic partridge genera, Margaroperdix of Madagascar and Anurophasis of alpine New Guinea, may represent additional examples of trans-marine dispersal in landfowl, but their body size and wing shape are typical of poorly dispersive continental species. Here, we estimate historical relationships of quail and their relatives using phylogenomics, and infer body size and wing shape evolution in relation to trans-marine dispersal events. Our results show that Margaroperdix and Anurophasis are nested within the Coturnix quail, and are each ‘island giants’ that independently evolved from dispersive, Coturnix-like ancestral populations that colonized and were subsequently isolated on Madagascar and New Guinea. This evolutionary cycle of gain and loss of dispersal ability, coupled with extinction of dispersive taxa, can result in the false appearance that non-vagile taxa somehow underwent rare oceanic dispersal.

扩散能力是决定物种岛屿分布格局与岛屿群落组成的关键因素，然而不善移动的陆生生物却广泛存在于大洋岛屿之上。陆禽（包括雉类、鹧鸪、松鸡、火鸡、鹑类及其近缘类群）普遍扩散能力较弱，但旧世界鹑属（Coturnix）却是显著的例外。该属鸟类演化出了小巧的体型与高展弦比的翼形，因此具备跨大陆迁徙与跨洋定殖的能力。另有两个单型鹧鸪属——马达加斯加的马岛鹧鸪属（Margaroperdix）与新几内亚高海拔地区的无尾鹧鸪属（Anurophasis）——或许代表了陆禽中跨海扩散的又两个案例，但它们的体型与翼形均符合扩散能力较弱的大陆类群特征。本研究通过系统发育基因组学方法解析鹑类及其近缘类群的系统发育关系，并推断与跨海扩散事件相关的体型与翼形演化历程。研究结果显示，马岛鹧鸪属与无尾鹧鸪属均嵌套于旧世界鹑属内部，二者均为“岛屿巨型类群”，分别由具有扩散能力、类似旧世界鹑的祖先类群定殖并随后分别隔离于马达加斯加与新几内亚后独立演化而来。这种扩散能力获得与丧失的演化循环，再加上具有扩散能力的类群的灭绝，会营造出一种假象：仿佛非移动性类群以某种方式实现了罕见的跨海扩散。