Mock K E, Evans R P, Crawford M, Cardall B L, Janecke S U, Miller M P
Department of Forest, Range, and Wildlife Sciences, Utah State University, Logan, Utah 84322-5230, USA.
Mol Ecol. 2006 Jul;15(8):2223-38. doi: 10.1111/j.1365-294X.2006.02932.x.
The Utah sucker (Catostomus ardens) is endemic to the Bonneville Basin and the upper Snake River drainage in western North America, and is thought to hybridize with the federally endangered June sucker (Chasmistes liorus mictus) in Utah Lake (Bonneville Basin). Here we describe the discovery of a major subdivision in Utah suckers (4.5% mitochondrial sequence divergence) between the ancient Snake River drainage and the Bonneville Basin. This boundary has not previously been recognized in Utah suckers based on morphologic variation, but has been recently described in two endemic cyprinids in the region. Populations in valleys east of the Wasatch Mountains in Utah clustered with the Snake River populations, suggesting that these valleys may have had an ancient hydrologic connection to the Snake River. We also found evidence of population isolation within the Bonneville Basin, corresponding to two Pleistocene sub-basins of the ancient Lake Bonneville. In contrast, we found no molecular evidence for deep divergence between Utah suckers and June suckers in Utah Lake or for a history of hybridization between divergent lineages in that population, although we recognize that demographic events may have obscured this signal. These findings suggest that the morphological differences between Utah and June suckers in Utah Lake may be the result of strong, and relatively recent, ecological selection. In summary, morphological and molecular characters seem to vary along different axes in different portions of the range of this taxon, providing an interesting system for studying the contributions of neutral and adaptive variation to species diversity.
犹他州吸口鱼（Catostomus ardens）是北美洲西部邦纳维尔盆地和斯内克河上游排水区域的特有物种，并且被认为在犹他湖（邦纳维尔盆地）与联邦濒危物种六月龄吸口鱼（Chasmistes liorus mictus）杂交。在此，我们描述了在古老的斯内克河排水区域和邦纳维尔盆地之间的犹他州吸口鱼中发现的一个主要分支（线粒体序列差异为4.5%）。基于形态学变异，此前在犹他州吸口鱼中尚未识别出这一边界，但最近在该区域的两种特有鲤科鱼类中已有描述。犹他州瓦萨奇山脉以东山谷中的种群与斯内克河种群聚类在一起，这表明这些山谷可能与斯内克河存在古老的水文联系。我们还发现了邦纳维尔盆地内种群隔离的证据，这与古老的邦纳维尔湖的两个更新世子盆地相对应。相比之下，我们没有发现分子证据表明犹他州吸口鱼与犹他湖中的六月龄吸口鱼之间存在深度分化，也没有发现该种群中不同谱系之间存在杂交历史的证据，尽管我们认识到种群统计学事件可能掩盖了这一信号。这些发现表明，犹他湖中的犹他州吸口鱼和六月龄吸口鱼之间的形态差异可能是强烈且相对近期的生态选择的结果。总之，形态学和分子特征似乎在该分类单元分布范围的不同部分沿着不同轴发生变化，为研究中性变异和适应性变异对物种多样性的贡献提供了一个有趣的系统。
