Abstract Barriers to gene flow in marine environments vary between species and are highly dependent on dispersal ability and habitat discontinuity. Intertidal sand and mud flats are discontinuous areas, separated by other habitat types along a coastline or by subtidal zones. The São Sebastião Channel in eastern Brazil, which is situated between Rio de Janeiro and São Paulo, harbors two intertidal mud flats where populations of the kinorhynch Echinoderes marthae are found, one on the mainland (Araçá Bay) and one on São Sebastião Island (Ilhabela). Here, we investigated the genetic structure of two E. marthae populations across the São Sebastião Channel, in order to contribute to the ongoing debate on biogeography of meiobenthic animals. Based on 628 bp of the mitochondrial CO1 gene, we find that E. marthae shows low levels of structure in the São Sebastião Channel (FST = 0.165), and find evidence of recent demographic expansion across populations.

中文翻译：

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跨越巴西圣塞巴斯蒂昂海峡的潮间带金丝雀 Echinoderes marthae (Kinorhyncha; Cyclorhagida; Echinoderidae) 的种群遗传结构

摘要 海洋环境中基因流动的障碍因物种而异，高度依赖于扩散能力和栖息地的不连续性。潮间带沙滩和泥滩是不连续的区域，由海岸线或潮下带的其他栖息地类型分隔。巴西东部的圣塞巴斯蒂昂海峡位于里约热内卢和圣保罗之间，有两个潮间带泥滩，在那里发现了刺猬针鳅种群，一个在大陆（阿拉萨湾），一个在圣塞巴斯蒂昂岛（伊利亚贝拉） ）。在这里，我们调查了圣塞巴斯蒂昂海峡两个 E. marthae 种群的遗传结构，以便为正在进行的小型底栖动物生物地理学辩论做出贡献。基于线粒体 CO1 基因的 628 bp，我们发现 E.