Using four criteria proposed a decade ago by Brooks & McLennan to identify a case of adaptive radiation indicates that the evolutionary history of the viviparous clade of the Gyrodactylidae is dominated by nonvicariant processes. The viviparous clade, with 446 species, has significantly more species than its sister clade (one species), and high species richness was shown to be an apomorphic trait of only the viviparous gyrodactylids within the Gyrodactylidae. Reconciliation of the phylogenetic tree of the viviparous Gyrodactylidae with that of its hosts showed a low probability for cospeciation suggesting that adaptive modes of speciation and not vicariance were predominant during the historical diversification of the clade. The proposed hypothesis suggests that the Gyrodactylidae originated on the South American continent about 60 Mya after geographical dispersal and host switching of its common ancestor to demersal freshwater catfishes by a marine ancestor. Development of hyperviviparity and the consequent loss of ‘sticky’ eggs in conjunction with other symplesiomorphic and apomorphic features allowed rapid diversification coupled with high dispersal to new host groups and geographical areas by viviparous members of the Gyrodactylidae.

中文翻译：

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胎生 Gyrodactylidae (Platyhelminthes, Monoogenoidea) 多样化的背景

使用 Brooks & McLennan 十年前提出的四个标准来确定适应性辐射的情况，表明 Gyrodactylidae 胎生进化枝的进化历史由非替代过程主导。胎生进化枝有 446 种，比其姊妹进化枝（一个物种）具有更多的物种，并且高物种丰富度被证明是仅在 Gyrodactylidae 中的胎生 gyrodactylids 的变形性状。胎生 Gyrodactylidae 的系统发育树与其宿主的系统发育树的协调表明共同物种形成的可能性很低，这表明在进化枝的历史多样化过程中，物种形成的适应性模式而不是替代模式占主导地位。提出的假设表明，Gyrodactylidae 起源于南美大陆约 60 米亚，经过地理扩散和海洋祖先将其共同祖先转变为底层淡水鲶鱼后。超胎生的发展和随之而来的“粘性”卵的丢失以及其他同形和异形特征允许快速多样化以及由 Gyrodactylidae 的胎生成员快速分散到新的宿主群体和地理区域。