Bowen B W, Grant W S
Department. of Fisheries and Aquatic Sciences, University of Florida, 7922 NW 71st Street, Gainesville, Florida, 32653-3071.
Department of Genetics, University of Witwatersrand, Johannesburg, 2050, South Africa.
Evolution. 1997 Oct;51(5):1601-1610. doi: 10.1111/j.1558-5646.1997.tb01483.x.
Sardines (Sardinops spp.) occupy temperate upwelling zones in the coastal regions of the Indian and Pacific Oceans, including locations in Japan, California, Chile, Australia, and South Africa. East and West Pacific populations are separated by vast expanses of open ocean, and northern and southern hemisphere populations are separated by tropical waters which are lethal to sardines. The relative importance of these barriers has been the focus of a longstanding debate between vicariance and dispersal schools in biogeography. Comparisons of a 500 bp fragment of the mitochondrial (mt) DNA control region reveal strong geographic structuring of mtDNA lineages but shallow divergence both within and between regional populations. Regional populations are related to one another in a stepping-stone pattern, the apparent result of a series of Pleistocene dispersal events around the continental margins of the Indian-Pacific Basin. These mtDNA data, combined with an electrophoretic survey of variability at 34 nuclear loci (Grant and Leslie 1996), indicate that the five regional forms of Sardinops (considered separate taxa by most authorities) probably diverged within 500,000 years BP, a much shorter timeframe than predicted by vicariance models based on plate tectonics. High mtDNA haplotype diversity, coupled with an excess of rare alleles in the protein electrophoretic dataset, may indicate exponential growth from a small ancestral population. The mtDNA and allozyme data are concordant with climate records and fossil evidence in portraying regional populations as recent, unstable, and ephemeral. Regional populations of sardines have probably been extinguished and recolonized over short evolutionary timescales in response to changes in climate and the oceanography of coastal upwelling zones.
沙丁鱼（沙丁鱼属）栖息在印度洋和太平洋沿海地区的温带上升流区域，包括日本、加利福尼亚、智利、澳大利亚和南非的一些地方。东太平洋和西太平洋的种群被广阔的公海隔开，北半球和南半球的种群被对沙丁鱼致命的热带水域隔开。这些屏障的相对重要性一直是生物地理学中区域分化学派和扩散学派之间长期争论的焦点。对线粒体（mt）DNA控制区500bp片段的比较显示，mtDNA谱系具有强烈的地理结构，但区域内和区域间种群的分化程度较浅。区域种群以踏脚石模式相互关联，这显然是印度-太平洋盆地大陆边缘一系列更新世扩散事件的结果。这些mtDNA数据，结合对34个核基因座变异性的电泳调查（格兰特和莱斯利，1996年），表明沙丁鱼的五种区域形态（大多数权威认为是不同的分类单元）可能在距今50万年以内分化，这一时间框架比基于板块构造的区域分化模型预测的要短得多。高mtDNA单倍型多样性，加上蛋白质电泳数据集中稀有等位基因的过量，可能表明一个小的祖先种群呈指数增长。mtDNA和等位酶数据与气候记录和化石证据一致，将区域种群描绘为近期的、不稳定的和短暂的。沙丁鱼的区域种群可能在短的进化时间尺度上因气候和沿海上升流区海洋学的变化而灭绝并重新定殖。
