Schönhuth Susana, Gagne Roderick B, Alda Fernando, Neely David A, Mayden Richard L, Blum Michael J
Department of Biology, Saint Louis University, St Louis, Missouri.
Department of Ecology and Evolutionary Biology, Tulane University, New Orleans, Louisiana.
J Fish Biol. 2018 Nov;93(5):778-791. doi: 10.1111/jfb.13778.
The extent and nature of genetic differentiation in Semotilus atromaculatus, one of the most abundant and widespread leuciscids in North America, were evaluated based on mitochondrial (mt) and nuclear DNA sequence variation. Phylogenetic relationships were first inferred based on a fragment of the cytochrome b (cytb) region and the nuclear intron s7 gene for S. atromaculatus and all other congeners as well as representative species from all other genera in the creek chub-plagopterin clade. The phylogeography of major haplogroups of S. atromaculatus was also assessed according to variation in a fragment of the mitochondrial cytb region from 567 individuals across its range. All analyses identified S. thoreauianus, S. lumbee and S. corporalis as reciprocally monophyletic groups. Analyses of nuclear sequence variation resolved S. atromaculatus as a single clade, where S. thoreauianus and S. lumbee were recovered as the sister group to S. atromaculatus, and S. corporalis was resolved as sister to all other species in the genus. Analyses of mtDNA sequence variation recovered S. atromaculatus as three well supported and differentiated monophyletic groups, with a widespread genetically homogeneous lineage extending across most of the current range of the species; a more geographically restricted and geographically structured lineage in the southern Appalachians, sister group to S. lumbee; and a geographically restricted lineage was identified from two Gulf Slope basins. Evidence of complex mito-nuclear discordance and phylogeographic differentiation within S. atromaculatus illustrates that further analysis of widespread species is warranted to understand North American freshwater fish diversity and distributions.
基于线粒体（mt）和核DNA序列变异，对北美最丰富且分布最广的亮鳍鱼科鱼类之一——黑斑美洲红点鲑（Semotilus atromaculatus）的遗传分化程度和性质进行了评估。首先，基于细胞色素b（cytb）区域的一个片段以及黑斑美洲红点鲑和所有其他同属物种的核内含子s7基因，还有溪鲈-斜鳍鱼进化枝中所有其他属的代表性物种，推断出系统发育关系。还根据来自黑斑美洲红点鲑分布范围内567个个体的线粒体cytb区域一个片段的变异，评估了黑斑美洲红点鲑主要单倍群的系统地理学。所有分析都确定，梭氏美洲红点鲑（S. thoreauianus）、拉姆比美洲红点鲑（S. lumbee）和粗壮美洲红点鲑（S. corporalis）为相互单系类群。核序列变异分析将黑斑美洲红点鲑解析为一个单一进化枝，其中梭氏美洲红点鲑和拉姆比美洲红点鲑被发现是黑斑美洲红点鲑的姐妹群，而粗壮美洲红点鲑被解析为该属所有其他物种的姐妹。线粒体DNA序列变异分析将黑斑美洲红点鲑解析为三个得到充分支持且有分化的单系类群，一个广泛分布且基因同质的谱系延伸至该物种当前大部分分布范围；在阿巴拉契亚山脉南部有一个地理分布更受限且有地理结构的谱系，是拉姆比美洲红点鲑的姐妹群；还有一个地理分布受限的谱系是从两个墨西哥湾沿岸盆地中确定的。黑斑美洲红点鲑内复杂的线粒体-核不一致性和系统地理分化证据表明，有必要对广泛分布的物种进行进一步分析，以了解北美淡水鱼的多样性和分布情况。
