Deep mitochondrial divergence in Baja California populations of an aquilopelagic elasmobranch: the golden cownose ray

Assessing the realized effect of dispersal in the genetic makeup of a species has significant evolutionary, ecological, and economical consequences. Here, we investigate the genetic diversity and population differentiation in the aquilopelagic golden cownose ray Rhinoptera steindachneri from the Gulf of California (GC) and the Pacific coast of Baja California (PCBC) using the mitochondrial NADH2 gene. Low levels of genetic diversity were found with only 4 polymerase chain reaction-restriction fragment length polymorphism haplotypes among 76 specimens. Pacific coast organisms were fixed for a unique haplotype not shared with rays from the gulf; 92% of GC rays possessed a single NADH2 haplotype not found in the Pacific. This produced significant differentiation between the GC and the PCBC (ΦCT = 0.972, P < 0.001). A pronounced phylogeographic pattern was found in which GC haplotypes were reciprocally monophyletic relative to a very divergent Pacific lineage (d = 10%). Our results indic...

评估物种扩散对其遗传构成的实际效应，具有重要的进化、生态与经济意义。本研究以加利福尼亚湾（Gulf of California, GC）及下加利福尼亚太平洋沿岸（Pacific coast of Baja California, PCBC）海域的远洋金黄牛鼻鲼（Rhinoptera steindachneri）为研究对象，采用线粒体NADH2基因（mitochondrial NADH2 gene）分析其遗传多样性与种群分化情况。研究在76份标本中仅检测到4个聚合酶链式反应-限制性片段长度多态性（polymerase chain reaction-restriction fragment length polymorphism, PCR-RFLP）单倍型（haplotype），显示整体遗传多样性水平较低。下加利福尼亚太平洋沿岸种群的所有个体均仅携带一种独有单倍型，与加利福尼亚湾种群无共享；92%的加利福尼亚湾个体仅拥有一种太平洋种群未检测到的NADH2单倍型。上述结果表明GC与PCBC种群间存在显著遗传分化（ΦCT=0.972, P<0.001）。研究还发现显著的系统地理格局：加利福尼亚湾种群的单倍型与高度分化的太平洋支系（遗传距离d=10%）互为单系群。本研究结果表明……