Salinity favorable for early development and gamete compatibility in two sympatric estuarine species of the genus Hediste (Polychaeta: Nereididae) in the Ariake Sea, Japan
Salinity favorable for early development and gamete compatibility in two sympatric estuarine species of the genus Hediste (Polychaeta: Nereididae) in the Ariake Sea, Japan
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DOI：
10.1007/s00227-005-0079-1
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发表时间：
2006-01-01
期刊：
影响因子：
2.4
通讯作者：
Sato, M
中科院分区：
文献类型：
--
作者：
Tosuji, H;Sato, M
本文研究了同域分布沙蚕Hediste japonica和沙蚕H. diadroma，其中参与了同时生殖群集在河口的大屋田川在有明海，日本。在27.5-30 psu盐度范围内，两种鱼的卵均为等渗性。在等渗盐度下，卵径为180-205 μ m。japonica，130-160 μ m;横裂在22.5-30 psu的盐度范围内观察到两个物种的大多数胚胎成功发育，而成功受精发生在更宽的盐度范围内，即，10-34 psu。japonica和10 ~ 30 psu。横裂在这两个物种中，自由游泳的幼虫生活开始于不清楚的孵化出果冻层胶囊的担轮幼虫。嗜卵细胞在H. japonica，而H.滞育，从而导致较短的浮游幼虫生活在H。日本。在Hediste种之间的幼虫形态的比较中，我们发现了一个明确的负相关关系之间的prostomium宽度，这代表幼虫的大小，并取决于卵的大小，和相对长度的毛状体的prostomium宽度：毛状体的相对长度是最长的H。diadroma（卵体积最小，生活时间长），H. japonica（卵大小中等，生活期短），而H. atoka（最大的蛋，没有真正的远洋生物）。我们还研究了H. japonica和H.通过交叉授精实验培育出了一种新的杂交种。两个物种的配子是亲合的，并通过实验室杂交产生了可行的杂种后代。杂交幼虫表示中间表型，但具有更大的母性影响的特征，如相对长度的毛和lecithotrophic幼虫持续时间。
Early development was examined, under various salinities, for two sympatric nereidid polychaetes, Hediste japonica and H. diadroma, which participated in a simultaneous reproductive swarming in an estuary of the Omuta-gawa River in Ariake Sea, Japan. The eggs of both species were isotonic to the medium of 27.5-30 psu salinity. The egg diameter in the isotonic salinity was 180-205 mu m in H. japonica, and 130-160 mu m in H. diadroma. Successful development of most embryos was observed in a salinity range of 22.5-30 psu in both species, while successful fertilization occurred in wider ranges of salinity, i.e., 10-34 psu in H. japonica and 10 to 30 psu in H. diadroma. In both species, free-swimming larval life started from the indistinct hatching of trochophores out of a jelly layer capsule. The lecithotrophic development appeared to run to the 4-setiger nectochaetes in H. japonica, while to 3-setiger nectochaetes in H. diadroma, resulting in a shorter pelagic larval life in H. japonica. In a comparison of larval morphology among Hediste species, we found a definite negative correlation between the prostomium width, which represents the larval size and depends on egg size, and relative length of chaetae to the prostomium width: the relative length of chaetae was the longest in H. diadroma (with the smallest egg size and long pelagic life), intermediate in H. japonica (intermediate egg size, short pelagic life), and the shortest in H. atoka (largest egg size, no true pelagic life). We also examined the possibility of hybridization between H. japonica and H. diadroma through cross-insemination experiments. The gametes of the two species were reciprocally compatible, and viable hybrid offspring were produced by the laboratory crosses. The hybrid larvae expressed intermediate phenotypes, but with a greater maternal influence in characteristics such as the relative length of chaetae and the lecithotrophic larval duration.