Rapid and repeated invasions of fresh water by the copepod Eurytemora affinis
Rapid and repeated invasions of fresh water by the copepod Eurytemora affinis
复制标题
DOI：
10.1111/j.1558-5646.1999.tb05407.x
复制
发表时间：
1999-10-01
期刊：
影响因子：
3.3
通讯作者：
Lee, CE
中科院分区：
文献类型：
--
作者：
Lee, CE
海洋生物对淡水的入侵引起了进化生物学家和古生物学家的极大兴趣，因为它们通常构成主要的进化转变。最近（< 200年）咸水或海洋物种对淡水的入侵为了解这些事件的机制提供了机会，但咸水入侵的途径尚未得到遗传数据的证实。本研究采用线粒体DNA序列（652个碱基对的细胞色素氧化酶I（COI）基因）重建的地理和淡水入侵的进化历史的共同河口和盐沼甲壳动物Eurytemora affinis（桡足类; Poppe 1880）。来自北美，欧洲和亚洲的种群的系统发育分析显示，至少有八个独立的淡水入侵来自遗传上不同的谱系。这些淡水入侵中至少有五个最有可能独立出现在不同的河流流域，最近从每个河流流域内的盐水来源。分子方差分析（AMOVA）进行了在三个地理尺度（大陆之间，排水之间，排水内），以评估遗传方差的层次分布。结果表明，52%的遗传变异解释的差异之间的排水，43%的大陆之间的差异，但只有5%的差异内的排水，从而支持地理模式的入侵推断的同源性。进行了生理实验，以确定是否成年人和幼虫从盐水人口可以容忍淡水条件。转移到零盐度导致高死亡率，但在一个群体中有一些存活到第二代。这项研究提供了遗传学证据和生理学支持，从盐水生活史到淡水的快速过渡，在全球范围内反复入侵。
Invasions of fresh water by marine organisms have been of great interest to evolutionary biologists and paleontologists because they typically constitute major evolutionary transitions. Recent (< 200 years) invasions of fresh water by brackish or marine species offer an opportunity to understand mechanisms underlying these events, but pathways of invasion from salt water have not been confirmed using genetic data. This study employed mitochondrial DNA sequences (652 base pairs from the cytochrome oxidase I(COI) gene) to reconstruct the geographic and evolutionary history of freshwater invasion by the common estuarine and saltmarsh crustacean Eurytemora affinis (Copepoda; Poppe 1880). Phylogenetic analysis of populations from North America, Europe, and Asia revealed at least eight independent invasions of fresh water from genetically distinct lineages. At least five of these freshwater invasions most likely arose independently in different river drainages, recently from saltwater sources within each river drainage. An analysis of molecular variance (AMOVA) was performed at three geographic scales (among continents, among drainages, and within drainages) to assess the hierarchical distribution of genetic variance. Results indicated that 52% of the genetic variance was explained by differences among drainages, 43% by differences among continents, but only 5% by differences within drainages, thus supporting geographic patterns of invasions inferred from the phylogeny. Physiological experiments were performed to determine whether adults and larvae from saltwater populations could tolerate freshwater conditions. Transfer to zero salinity resulted in high mortalities, bur with some survival to the second generation in one population. This study provides genetic evidence and physiological support for rapid transitions from a saline life history into fresh water, with repeated invasions on a global scale.