Johnson Jerald B
Conservation Biology Division, National Marine Fisheries Service, Seattle, Washington 98112, USA.
Evolution. 2002 May;56(5):948-60. doi: 10.1111/j.0014-3820.2002.tb01407.x.
The Bonneville Basin and upper Snake River drainage of western North America underwent extensive hydrological changes during the late Pleistocene, potentially influencing the geographic distribution and evolutionary trajectories of aquatic species that occupied this region. To test this hypothesis, I reconstructed the phylogeographic history of the desert fish Utah chub (Gila atraria) by examining 16 populations that span the natural distribution of this species across the Bonneville Basin and upper Snake River. I compared mitochondrial control region sequences (934 bp) among 77 individuals revealing 24 unique haplotypes. Geographic and phylogenetic relationships among haplotypes were explored using parsimony, maximum likelihood, nested clade analysis, and analysis of molecular variance. I found that G. atraria is composed of two distinct clades that represent an early Pleistocene split between the upper Snake River and Bonneville Basin. Within each of these clades, geographic structuring was highly concordant with the hydrological history of late Pleistocene Lake Bonneville and the upper Snake River, suggesting that glacial-induced shifts in climate and unpredictable geological events have played a major role in shaping genetic subdivision among populations. To examine the effects of vicariant events on phenotypic divergence among Utah chub populations, I mapped chub life histories to the control region haplotype network. I found a nonrandom association between haplotypes and life-history phenotypes. These results suggest that historical events responsible for population fragmentation may have also contributed to phenotypic shifts in life histories, both indirectly by limiting gene flow among populations and directly by altering the selective environments where populations persisted.
北美西部的邦纳维尔盆地和斯内克河上游流域在晚更新世经历了广泛的水文变化，这可能影响了占据该地区的水生物种的地理分布和进化轨迹。为了验证这一假设，我通过研究跨越邦纳维尔盆地和斯内克河上游该物种自然分布范围的16个种群，重建了沙漠鱼类犹他鲃（Gila atraria）的系统地理学历史。我比较了77个个体的线粒体控制区序列（934 bp），发现了24个独特的单倍型。使用简约法、最大似然法、嵌套分支分析和分子方差分析探索了单倍型之间的地理和系统发育关系。我发现犹他鲃由两个不同的分支组成，这代表了早更新世斯内克河上游和邦纳维尔盆地之间的分化。在每个分支中，地理结构与晚更新世邦纳维尔湖和斯内克河上游的水文历史高度一致，这表明冰川引起的气候变化和不可预测的地质事件在塑造种群间的遗传细分方面发挥了重要作用。为了研究替代事件对犹他鲃种群表型分化的影响，我将鲃的生活史映射到控制区单倍型网络上。我发现单倍型与生活史表型之间存在非随机关联。这些结果表明，导致种群分裂的历史事件可能也促成了生活史的表型转变，这既通过限制种群间的基因流动间接实现，也通过改变种群生存的选择环境直接实现。
