Data from: Repeated evolution of amphibious behavior in fish and its implications for the colonisation of novel environments

We know little about on how frequently transitions into new habitats occur, especially the colonisation of novel environments that are the most likely to instigate adaptive evolution. One of the most extreme ecological transitions has been the shift in habitat associated with the move from water to land by amphibious fish. We provide the first phylogenetic investigation of these transitions for living fish. Thirty-three families have species reported to be amphibious and these are likely independent evolutionary origins of fish emerging onto land. Phylogenetic reconstructions of closely related taxa within one of these families, the Blenniidae, inferred as many as seven convergences on a highly amphibious lifestyle. Taken together, there appear to be few constraints on fish emerging onto land given amphibious behavior has evolved repeatedly many times across ecologically diverse families. The colonisation of novel habitats by other taxa resulting in less dramatic changes in environment should be equally, if not, more frequent in nature, providing an important pre-requisite for subsequent adaptive differentiation.

目前学界对生物迁入新栖息地的频率知之甚少，尤其是那些最可能引发适应性进化的全新环境拓殖事件。两栖鱼类从水生到陆生的生境转变，是最为极端的生态转型案例之一。本研究首次针对现生鱼类的这类生境转型开展了系统发育（phylogenetic）分析。目前已有33个鱼类科被报道存在具备两栖习性的物种，这些类群大概率独立演化出了登陆行为。针对其中一个类群——鳚科（Blenniidae）内的近缘类群进行的系统发育重建结果显示，其高度两栖的生活方式至少独立演化了7次。综合来看，鉴于两栖行为在多个生态多样的鱼类科中反复独立演化，鱼类登陆似乎几乎不受演化约束。若其他类群拓殖的新环境所带来的环境变化幅度相对更小，那么这类拓殖事件在自然界中的发生频率即便不算更高，也至少与鱼类登陆相当——而这正是后续适应性分化的重要前提。