Dispersal, vicariance, and timing of diversification in Nothonotus darters
Dispersal, vicariance, and timing of diversification in Nothonotus darters
复制标题
Nothonotus 蛇鲈的扩散、替代性和多样化时间
作者：
T. Near;Benjamin P. Keck
北美淡水鱼类的物种多样性在地球温带地区是无与伦比的。这种多样性集中在北美东部的中部高地，这种分布模式激发了涉及分散或变异的不同模型来解释北美鱼类的高度物种多样性。这些模型中最受欢迎的是中央高地替代假说（CHVH），该假说提出了一种古老且多样化的广泛动物群，存在于以前连续的高地景观中，与今天有很大不同。 CHVH 中的隔离机制涉及影响中央高地鱼类几个不同谱系的具体实例。我们使用蛇鲈分支 Nothonotus 的细胞色素 b 推断系统发育测试了 CHVH 和替代模型的预测。使用贝叶斯混合模型方法进行系统发育分析。系统发育数据集包括所有 20 个已识别的 Nothonotus 物种，并且大多数物种都用多个序列表示。我们能够使用淡水鲈形鱼分支 Centarchidae 中的外部化石校准将遗传分支长度转换为绝对年龄。使用解析良好的Nothonotus系统发育和分化时间估计，我们确定了中部高地不连续区域中相同数量的替代和扩散实例、生物地理伪一致性、Nothonotus相当新的物种形成以及高地地区内令人惊讶的大量物种形成。关于Nothonotus，以前的中央高地生物地理模型几乎没有提供负责该进化枝多样化的可能机制。 Nothonotus 的物种形成模式与最近的研究中发现的模式相似，这些研究已将物种形成作为参数纳入岛屿生物地理学的经典模型中。
The species diversity of North American freshwater fishes is unparalleled among temperate regions of the planet. This diversity is concentrated in the Central Highlands of eastern North America and this distribution pattern has inspired different models involving either dispersal or vicariance to explain the high species diversity of North American fishes. The most popular of these models is the Central Highlands vicariance hypothesis (CHVH), which proposes an ancient and diverse widespread fauna that existed across a previously continuous highland landscape that is much different from today. The mechanisms of isolation in the CHVH involve specific instances of vicariance that affected several diverse lineages of Central Highlands fishes. We tested predictions of the CHVH and alternative models using a cytochrome b‐inferred phylogeny of the darter clade Nothonotus. A Bayesian mixed‐model method was used for phylogenetic analysis. The phylogenetic data set included all 20 recognized Nothonotus species, and most species were represented with multiple sequences. We were able to convert genetic branch lengths to absolute age using external fossil calibrations in the freshwater perciform fish clade Centrarchidae. Using a well‐resolved Nothonotus phylogeny and divergence time estimates, we identify equal numbers of instances of both vicariance and dispersal among disjunct regions of the Central Highlands, biogeographic pseudocongruence, rather recent speciation in Nothonotus, and a surprisingly large amount of speciation within highland areas. With regard to Nothonotus, previous Central Highlands biogeographic models offer little in the way of providing possible mechanisms responsible for diversification in the clade. Patterns of speciation in Nothonotus are similar to those discovered in recent efforts that have included speciation as a parameter into classic models of island biogeography.