Hybridization and F1 backcrosses between two closely related tropical species of sea urchins (genus Echinometra) in Okinawa
Hybridization and F1 backcrosses between two closely related tropical species of sea urchins (genus Echinometra) in Okinawa
复制标题
DOI：
10.1080/07924259.1997.9672591
复制
发表时间：
1997-01-01
影响因子：
0.8
通讯作者：
Uehara, T
中科院分区：
文献类型：
--
作者：
Aslan, LM;Uehara, T
有四种刺胆属的海胆，分别是A、B、C和D种，分布在冲绳沿岸；它们通过颜色图案和其他特征来区分。通过一系列的受精试验和对杂交后代的饲养，研究了两个最明显的物种——刺尖为白色的棘腹虫sp. A （Ea）和刺尖接近黑色的棘腹虫sp. D （Ed）的杂交潜力。施肥是相互不对称的；Ed的卵子很容易被Ea的精子受精，但只有不到20%的Ea的卵子被Ed的精子受精。然而，两个方向杂交产生的杂交种在幼虫期和幼年期发育正常，产生性成熟的成虫。Ed雄xEa雌和Ed雌xEa雄的幼虫比Ea雌xEa雄和Ea雌xEa雄的幼虫大，反映了Ed的卵较大，但Ea雌xEa雄的幼体和后期直至成熟期始终大于其他同龄杂交的幼虫；从大到小依次为Ea female xEa male、Ed female xEa male、Ea female xEd male和Ed female xEd male。在所有杂交组合中，虽然Ed雌性xEa雄性杂交的受精率始终高于Ea雌性xEa雄性杂交的受精率，但它们的卵子和精子都是活的和可受精的。这些实验代表了首次报道成功生产具有活配子的杂交海胆。这表明这两个物种的生殖隔离是通过前合子隔离机制实现的。在这些机制中，配子不相容可能只是部分参与，如果有的话，产卵时间、栖息地隔离或其他因素的差异似乎对维持这些密切相关物种的生殖隔离很重要。
Four species of sea urchins of the genus Echinometra, designated species A, B, C, and D, occur along the coast of Okinawa; they are distinguished by color pattern and other characteristics. The two most distinct species, Echinometra sp. A (Ea) with white-tipped spines and Echinometra sp. D (Ed) with nearly black spines (possibly E. oblonga), were examined for potential hybridization through a series of fertilization experiments and rearing of the resulting hybrids. Fertilization was reciprocally asymmetrical; Ed ova were readily fertilized by sperm of Ea, but less than 20% of the ova of Ea were fertilized by sperm of Ed. Nevertheless, hybrids resulting from crosses in both directions developed normally through larval and juvenile stages to produce sexually mature adults. Larvae of Ed male xEa female and Ed female xEd male were larger than those of Ea female xEd male and Ea female xEa male, reflecting the larger eggs of Ed. However, Ea female xEa male juveniles and later stages, up to maturity, were consistently larger than those of equivalent ages of the other crosses; largest to smallest were Ea female xEa male, Ed female xEa male, Ea female xEd male, and Ed female xEd male, respectively. Ova and sperm of the hybrids were viable and fertilizable in all combination of crosses, although fertilization of those of Ed female xEa male hybrids was consistently higher than those of Ea female xEd male hybrids. These experiments represent the first reported successful production of hybrid sea urchins with viable gametes. They indicate that reproductive isolation is achieved by prezygotic isolating mechanisms in these two species. Of these mechanisms, gametic incompatibility is probably only partly involved, if at all, and differences in spawning times, habitat segregation, or other factors appear to be important for maintaining reproductive isolation in these closely related species.