Kokkonen Andrea L, Searle Peter C, Shiozawa Dennis K, Evans R Paul
Department of Microbiology and Molecular Biology Brigham Young University Provo Utah USA.
Department of Ecology and Evolutionary Biology Cornell University Ithaca New York USA.
Evol Appl. 2024 Jul 11;17(7):e13735. doi: 10.1111/eva.13735. eCollection 2024 Jul.
For almost 200 years, the taxonomy of cutthroat trout (), a salmonid native to Western North America, has been in flux as ichthyologists and fisheries biologists have tried to describe the diversity within these fishes. Starting in the 1950s, Robert Behnke reexamined the cutthroat trout and identified 14 subspecies based on morphological traits, Pleistocene events, and modern geographic ranges. His designations became instrumental in recognizing and preserving the remaining diversity of cutthroat trout. Over time, molecular techniques (i.e. karyotypes, allozymes, mitochondrial DNA, SNPs, and microsatellite arrays) have largely reinforced Behnke's phylogenies, but have also revealed that some relationships are consistently weakly supported. To further resolve these relationships, we generated de novo transcriptomes for nine cutthroat subspecies, as well as a Bear River Bonneville form and two Colorado River lineages (blue and green). We present phylogenies of these subspecies generated from multiple sets of orthologous genes extracted from our transcriptomes. We confirm many of the relationships identified in previous morphological and molecular studies, as well as discuss the importance of significant differences apparent in our phylogenies from these studies within a geological perspective. Specific findings include three distinct clades: (1) Bear River Bonneville form and Yellowstone cutthroat trout; (2) Bonneville cutthroat trout ( = 2); and (3) Greenback and Rio Grande cutthroat trout. We also identify potential gene transfer between Bonneville cutthroat trout and a population of Colorado River green lineage cutthroat trout. Using these findings, it appears that additional groups warrant species-level consideration if other recent species elevations are retained.
近200年来,北美西部本土的鲑科鱼类——割喉鳟(Oncorhynchus clarkii)的分类一直处于变动之中,因为鱼类学家和渔业生物学家一直在努力描述这些鱼类的多样性。从20世纪50年代开始,罗伯特·贝恩克重新审视了割喉鳟,并根据形态特征、更新世事件和现代地理分布确定了14个亚种。他的分类对于识别和保护割喉鳟剩余的多样性起到了重要作用。随着时间的推移,分子技术(即核型、等位酶、线粒体DNA、单核苷酸多态性和微卫星阵列)在很大程度上强化了贝恩克的系统发育关系,但也揭示出一些关系始终缺乏有力支持。为了进一步解决这些关系问题,我们为9个割喉鳟亚种以及一种贝尔河博纳维尔形态和两个科罗拉多河谱系(蓝色和绿色)生成了从头转录组。我们展示了从我们的转录组中提取的多组直系同源基因所生成的这些亚种的系统发育关系。我们证实了先前形态学和分子研究中确定的许多关系,并从地质角度讨论了我们的系统发育关系中与这些研究相比明显存在的显著差异的重要性。具体发现包括三个不同的进化枝:(1)贝尔河博纳维尔形态和黄石割喉鳟;(2)博纳维尔割喉鳟(Oncorhynchus clarkii utah = 2);以及(3)绿背割喉鳟和格兰德河割喉鳟。我们还确定了博纳维尔割喉鳟与科罗拉多河绿色谱系割喉鳟种群之间存在潜在的基因转移。利用这些发现,如果保留其他近期的物种提升,似乎还有其他群体值得进行物种水平的考量。