Department of Biology, Population and Conservation Biology Program, Texas State University, San Marcos, TX.
Department of Biology, University of Konstanz, Konstanz, Germany.
J Hered. 2019 May 7;110(3):361-369. doi: 10.1093/jhered/esz004.
In recent decades, an increased understanding of molecular ecology has led to a reinterpretation of the role of gene flow during the evolution of reproductive isolation and biological novelty. For example, even in the face of ongoing gene flow strong selection may maintain divergent polymorphisms, or gene flow may introduce novel biological diversity via hybridization and introgression from a divergent species. Herein, we elucidate the evolutionary history and genomic basis of a trophically polymorphic trait in a species of cichlid fish, Herichthys minckleyi. We explored genetic variation at 3 hierarchical levels; between H. minckleyi (n = 69) and a closely related species Herichthys cyanoguttatus (n = 10), between H. minckleyi individuals from 2 geographic locations, and finally between individuals with alternate morphotypes at both a genome-wide and locus-specific scale. We found limited support for the hypothesis that the H. minckleyi polymorphism is the result of ongoing hybridization between the 2 species. Within H. minckleyi we found evidence of geographic genetic structure, and using traditional population genetic analyses found that individuals of alternate morphotypes within a pool appear to be panmictic. However, when we used a locus-specific approach to examine the relationship between multi-locus genotype, tooth size, and geographic sampling, we found the first evidence for molecular genetic differences between the H. minckleyi morphotypes.
近几十年来，对分子生态学的深入了解导致了对基因流在生殖隔离和生物新颖性进化过程中作用的重新解释。例如，即使存在持续的基因流，强烈的选择也可能维持分歧的多态性，或者基因流可能通过杂交和来自分歧物种的渐渗引入新的生物多样性。在此，我们阐明了慈鲷鱼种 Herichthys minckleyi 中一种营养多态性特征的进化历史和基因组基础。我们在 3 个层次上探索了遗传变异；在 H. minckleyi（n = 69）和密切相关的物种 Herichthys cyanoguttatus（n = 10）之间、在来自 2 个地理地点的 H. minckleyi 个体之间，以及在基因组范围和特定基因座的个体之间具有交替形态类型之间。我们发现，H. minckleyi 多态性是两种物种之间持续杂交的结果的假设几乎没有得到支持。在 H. minckleyi 内部，我们发现了地理遗传结构的证据，并且使用传统的种群遗传分析发现，在一个群体中具有交替形态类型的个体似乎是同种的。然而，当我们使用特定基因座的方法来研究多基因座基因型、牙齿大小和地理采样之间的关系时，我们发现了 H. minckleyi 形态类型之间分子遗传差异的第一个证据。
