Data from: Influence of introgression and geological processes on phylogenetic relationships of western North American mountain suckers (Pantosteus, Catostomidae)

Intense geological activity caused major topographic changes in Western North America over the past 15 million years. Major rivers here are composites of different ancient rivers, resulting in isolation and mixing episodes between river basins over time. This history influenced the diversification of most of the aquatic fauna. The genus Pantosteus is one of several clades centered in this tectonically active region. The eight recognized Pantosteus species are widespread and common across southwestern Canada, western USA and into northern Mexico. They are typically found in medium gradient, middle-elevation reaches of rivers over rocky substrates. This study (1) compares molecular data with morphological and paleontological data for proposed species of Pantosteus, (2) tests hypotheses of their monophyly, (3) uses these data for phylogenetic inferences of sister-group relationships, and (4) estimates timing of divergence events of identified lineages. Using 8055 base pairs from mitochondrial DNA protein coding genes, Pantosteus and Catostomus are reciprocally monophyletic, in contrast with morphological data. The only exception to a monophyletic Pantosteus is P. columbianus whose mtDNA is closely aligned with C. tahoensis because of introgression. Within Pantosteus, several species have deep genetic divergences among allopatric sister lineages, several of which are diagnosed and elevated to species, bringing the total diversity in the group to 11 species. Conflicting molecular and morphological data may be resolved when patterns of divergence are shown to be correlated with sympatry and evidence of introgression.

过去1500万年间，强烈的地质活动引发了北美西部大范围的地形变迁。该区域的主要河流均由多条古河道复合而成，随时间推移导致流域间出现隔离与交汇事件。这一地质历史进程影响了该区域多数水生动物类群的物种分化。Pantosteus属（Pantosteus）是多个以该构造活跃区域为分布中心的演化支之一。目前已被确认的8种Pantosteus属鱼类广泛分布于加拿大西南部、美国西部以及墨西哥北部区域，种群较为常见。该属鱼类通常栖息于底质多岩石、坡度中等的中海拔河段。本研究（1）针对Pantosteus属的拟议物种，将分子数据与形态学、古生物学数据进行对比分析；（2）验证其单系性假说；（3）利用上述数据对姊妹群亲缘关系开展系统发育推断；（4）估算已确认演化支的分化时间节点。本研究基于线粒体DNA蛋白编码基因的8055个碱基对序列开展分析，结果显示Pantosteus属与Catostomus属（Catostomus）互为单系群，这与形态学数据的结论相悖。唯一打破Pantosteus属单系性的类群是P. columbianus，由于基因渐渗（introgression）事件，其线粒体DNA与C. tahoensis的线粒体DNA高度同源。在Pantosteus属内部，多个现有物种在异域分布的姊妹演化支间存在显著的遗传分化，其中部分类群已被重新界定并提升为独立物种，使得该属的总物种数增至11种。当分化模式被证实与同域分布及基因渐渗证据相关时，分子与形态学数据间的冲突便可得到合理解释。