Data from: Do habitat shifts drive the diversity in teleost fishes? An example from the pufferfishes (Tetraodontidae)

Habitat shifts are implicated as the cause of many vertebrate radiations, yet relatively few empirical studies quantify patterns of diversification following colonization of new habitats in fishes. The pufferfishes (family Tetraodontidae) occur in several habitats, including coral reefs and freshwater, which are thought to provide ecological opportunity for adaptive radiation, and thus provide a unique system for testing the hypothesis that shifts to new habitats alter diversification rates. To test this hypothesis we sequenced eight genes for 96 species of pufferfishes and closely related porcupine fishes, and added 19 species from sequences available in GenBank. We time-calibrated the molecular phylogeny using three fossils, and performed several comparative analyses to test whether colonization of novel habitats led to shifts in the rate of speciation and body size evolution, central predictions of clades experiencing ecological adaptive radiation.. Colonization of freshwater is associated with lower rates of cladogenesis in pufferfishes though these lineages also exhibit accelerated rates of body size evolution. Increased rates of cladogenesis are associated with transitions to coral reefs, but reef lineages surprisingly exhibit significantly lower rates of body size evolution. These results suggest that ecological opportunity afforded by novel habitats may be limited for pufferfishes due to competition with other species, constraints relating to pufferfish life history and trophic ecology, and other factors.

生境转移被视作诸多脊椎动物演化辐射的核心成因，但目前针对鱼类迁入新生境后的多样化格局开展的实证研究仍相对稀缺。四齿鲀科（Tetraodontidae）鲀类的栖息生境多样，涵盖珊瑚礁与淡水环境，这类生境被认为可为适应辐射提供生态机遇，因此为检验“迁入新生境会改变演化多样化速率”这一假说提供了绝佳的研究系统。为验证该假说，我们对96种鲀类及近缘刺鲀的8个基因进行了测序，并补充了从基因银行（GenBank）获取的19个物种的公开序列数据。我们借助3个化石标定点对分子系统发育树进行时间校准，并开展多项比较分析，以检验新环境定植是否会引发物种形成速率与体型演化速率的改变——这正是经历生态适应辐射的支系的核心预测方向。研究结果显示，淡水生境定植与鲀类较低的分支演化速率相关，但该类支系的体型演化速率却显著加快。珊瑚礁生境定植则与更高的分支演化速率相关，但令人意外的是，珊瑚礁支系的体型演化速率反而显著降低。上述结果表明，新环境所提供的生态机遇可能对鲀类存在局限，其潜在原因包括与其他物种的种间竞争、鲀类自身生活史与营养生态的约束，以及其他尚未明确的因素。