Mitochondrial DNA cytochrome oxidase (COI) and microsatellite DNA loci were used to better explain the speciation events, history of hybridization, and genetic population structure of the stone crabs Menippe adinaWilliams & Felder, 1986 and M. mercenaria (Say, 1817–1818). A survey of a 670-bp COI sequence of 711 stone crabs collected from Texas to North Carolina and from Belize, Central America showed the presence of two well-defined mtDNA lineages, Lin-A and Lin-B. Based on molecular clock calibrations of a published study these lineages shared a common ancestor between 1.5 to 1.8 million years. Lin-A was evident throughout the range of the two Menippe species, but Lin-B was found only in the eastern Gulf of Mexico and does not represent any of the two species. Our findings refute the claim that the eastern Gulf hybrid zone is the product of hybridization between M. adina and M. mercenaria. We propose that the hybrid zone is instead a relic of introgressive hybridization between the M. mercenaria of eastern Gulf stone crab nDNA Lin-AA that carries Lin-A and the new nDNA Lin-BB that carries Lin-B, forming the hybrid nDNA Lin-AB. Lin-B emerged from a founder effect in the Okefenokee Trough and introgressed into the eastern Gulf. There is no Lin-B in the Atlantic, hence no hybridization in that region. Using stone crab-specific microsatellite markers we found no evidence of an ongoing hybridization in the eastern Gulf and this region cannot be called a hybrid zone since hybridization here ceased probably soon after the last glacial episode. The microsatellite-marker analyses also suggested that the stone crab was geographically divided into four genetic clusters by three barriers to gene flow, the strongest of which is the one between the two species, M. adina and M. mercenaria, around Cape San Blas, Apalachicola Bay, Florida.

中文翻译：

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对石蟹 Menippe mercenaria (Say, 1817–1818) 和 M. adina Williams & Felder, 1986 (十足目: Brachyura: Menippidae) 的物种形成、杂交和遗传种群结构的新解释

线粒体 DNA 细胞色素氧化酶 (COI) 和微卫星 DNA 基因座被用来更好地解释石蟹 Menippe adinaWilliams & Felder, 1986 和 M. mercenaria (Say, 1817–1818) 的物种形成事件、杂交历史和遗传种群结构。对从德克萨斯州到北卡罗来纳州和中美洲伯利兹收集的 711 只石蟹的 670-bp COI 序列的调查显示，存在两个明确定义的 mtDNA 谱系，即 Lin-A 和 Lin-B。根据一项已发表研究的分子钟校准，这些谱系在 1.5 到 180 万年之间有一个共同的祖先。Lin-A 在两个 Menippe 物种的范围内都很明显，但 Lin-B 仅在墨西哥湾东部发现，并不代表这两个物种中的任何一个。我们的研究结果驳斥了东部海湾混合区是 M. adina 和 M. mercenaria 杂交产物的说法。我们提出，杂交区是东部海湾石蟹 nDNA Lin-AA 的 M. mercenaria 携带 Lin-A 和携带 Lin-B 的新 nDNA Lin-BB 之间渐渗杂交的遗物，形成杂交 nDNA Lin -AB。Lin-B 从 Okefenokee Trough 的创始效应中出现并渗入东部海湾。大西洋没有 Lin-B，因此该地区没有杂交。使用石蟹特异性微卫星标记，我们发现没有证据表明海湾东部正在进行杂交，该地区不能称为杂交区，因为这里的杂交可能在最后一次冰期后不久就停止了。