长距离扩散在进化中起着关键作用,促进异型发散,范围扩展,和物种运动对环境变化的反应。即使是看起来不太适合传播的物种有时也可以长途旅行,例如通过与其他人搭便车,更多本质上分散的物种。在海洋大型藻类中,浮力可以使成年人和不同的搭便车者能够长距离漂流,但是这种特征的演变和作用却知之甚少。南部公牛海带属Durvillaea包括几种非浮力和浮力物种,包括一些最近才被认可的。在修改属的时候,我们不仅提供更新的识别工具,还描述了两个新物种(D.incurvata梳子。11月。来自智利和D.fenestratasp.11月。来自对端群岛),还要进行生物地理分析,以确定该属浮力的进化史。尽管祖先状态被认为是不活跃的,物种的分布表明这种特性已经获得和丢失,可能不止一次。我们得出的结论是,尽管浮力是一种对分散有用的特征(为其收益创造进化压力),它的损失也有进化压力,因为它将物种限制在狭窄的环境范围内(即,浅深度)。
Long-distance dispersal plays a key role in evolution, facilitating allopatric divergence, range expansions, and species movement in response to environmental change. Even species that seem poorly suited to dispersal can sometimes travel long distances, for example via hitchhiking with other, more intrinsically dispersive species. In marine macroalgae,
buoyancy can enable adults-and diverse hitchhikers-to drift long distances, but the evolution and role of this trait are poorly understood. The southern bull-kelp genus Durvillaea includes several non-buoyant and buoyant species, including some that have only recently been recognized. In revising the genus, we not only provide updated identification tools and describe two new species (D. incurvata comb. nov. from Chile and D. fenestrata sp. nov. from the Antipodes Islands), but also carry out biogeographic analyses to determine the evolutionary history of
buoyancy in the genus. Although the ancestral state was resolved as non-buoyant, the distribution of species suggests that this trait has been both gained and lost, possibly more than once. We conclude that although
buoyancy is a trait that can be useful for dispersal (creating evolutionary pressure for its gain), there is also evolutionary pressure for its loss as it restricts species to narrow environmental ranges (i.e., shallow depths).