Grunwald C, Stabile J, Waldman J R, Gross R, Wirgin I
Nelson Institute of Environmental Medicine, New York University School of Medicine, 57 Old Forge Road, Tuxedo, NY 10987, USA.
Mol Ecol. 2002 Oct;11(10):1885-98. doi: 10.1046/j.1365-294x.2002.01575.x.
Shortnose sturgeon is an anadromous North American acipenserid that since 1973 has been designated as federally endangered in US waters. Historically, shortnose sturgeon occurred in as many as 19 rivers from the St. John River, NB, to the St. Johns River, FL, and these populations ranged in census size from 10(1) to 10(4), but little is known of their population structure or levels of gene flow. We used the polymerase chain reaction (PCR) and direct sequence analysis of a 440 bp portion of the mitochondrial DNA (mtDNA) control region to address these issues and to compare haplotype diversity with population size. Twenty-nine mtDNA nucleotide-substitution haplotypes were revealed among 275 specimens from 11 rivers and estuaries. Additionally, mtDNA length variation (6 haplotypes) and heteroplasmy (2-5 haplotypes for some individuals) were found. Significant genetic differentiation (P < 0.05) of mtDNA nucleotide-substitution haplotypes and length-variant haplotypes was observed among populations from all rivers and estuaries surveyed with the exception of the Delaware River and Chesapeake Bay collections. Significant haplotype differentiation was even observed between samples from two rivers (Kennebec and Androscoggin) within the Kennebec River drainage. The absence of haplotype frequency differences between samples from the Delaware River and Chesapeake Bay reflects a probable current absence of spawning within the Chesapeake Bay system and immigration of fish from the adjoining Delaware River. Haplotypic diversity indices ranged between 0.817 and 0.641; no relationship (P > 0.05) was found between haplotype diversity and census size. Gene flow estimates among populations were often low (< 2.0), but were generally higher at the latitudinal extremes of their distribution. A moderate level of haplotype diversity and a high percentage (37.9%) of haplotypes unique to the northern, once-glaciated region suggests that northern populations survived the Pleistocene in a northern refugium. Analysis of molecular variance best supported a five-region hierarchical grouping of populations, but our results indicate that in almost all cases populations of shortnose sturgeon should be managed as separate units.
短吻鲟是一种溯河洄游的北美鲟科鱼类，自1973年以来在美国水域被列为联邦濒危物种。历史上，短吻鲟曾出现在从新不伦瑞克省的圣约翰河到佛罗里达州的圣约翰斯河的多达19条河流中，这些种群的普查规模从10（1）到10（4）不等，但对它们的种群结构或基因流动水平了解甚少。我们使用聚合酶链反应（PCR）和对线粒体DNA（mtDNA）控制区440 bp部分的直接序列分析来解决这些问题，并将单倍型多样性与种群规模进行比较。在来自11条河流和河口的275个样本中发现了29种mtDNA核苷酸替代单倍型。此外，还发现了mtDNA长度变异（6种单倍型）和异质性（一些个体有2 - 5种单倍型）。在所调查的所有河流和河口的种群中，除了特拉华河和切萨皮克湾的样本外，mtDNA核苷酸替代单倍型和长度变异单倍型都存在显著的遗传分化（P < 0.05）。甚至在肯纳贝克河流域内的两条河流（肯纳贝克河和安德罗斯科金河）的样本之间也观察到了显著的单倍型分化。特拉华河和切萨皮克湾样本之间单倍型频率没有差异，这反映出切萨皮克湾系统目前可能没有产卵现象，且有来自相邻特拉华河的鱼类迁入。单倍型多样性指数在0.817至0.641之间；未发现单倍型多样性与普查规模之间存在关系（P > 0.05）。种群间的基因流动估计值通常较低（< 2.0），但在其分布的纬度极端地区通常较高。中等水平的单倍型多样性以及北部曾经被冰川覆盖地区特有的单倍型比例较高（37.9%），这表明北部种群在更新世期间在北部避难所中存活了下来。分子方差分析最支持将种群分为五个区域的层次分组，但我们的结果表明，在几乎所有情况下，短吻鲟种群都应作为独立的单位进行管理。
