Hybrids of Two Closely Related Tropical Sea Urchins (Genus Echinometra): Evidence Against Postzygotic Isolating Mechanisms
Hybrids of Two Closely Related Tropical Sea Urchins (Genus Echinometra): Evidence Against Postzygotic Isolating Mechanisms
复制标题
两种密切相关的热带海胆（海胆属）的杂交：反对合子后隔离机制的证据
DOI：
10.2307/1543303
复制
发表时间：
2001
期刊：
影响因子：
--
通讯作者：
John S. Pearse
中科院分区：
文献类型：
--
作者：
M. Aminur Rahman;T. Uehara;John S. Pearse
以马泰棘孔海胆（Echinometra mathaei species complex）中的两种同域海胆（Echinometra sp. A（Ea）和Echinometra sp. C（Ec））为材料，进行了一系列的异卵受精试验。当Ec的卵子和Ea的精子参与时，异配子受精成功率较高，而Ea的卵子和Ec的精子参与时，异配子受精成功率较低。两个方向杂交产生的杂种均能正常发育至性成熟成虫; Ea × Ea的试验大小最大，其次分别是Ec（卵）× Ea（精子）、Ea（卵）× Ec（精子）和Ec × Ec。杂交种的颜色模式更接近母体着色，而其他字符，如相对测试尺寸和脊柱长度，管足和性腺骨针的形态，配子大小的中间。F1回交的受精率很高，最大限度地减少了杂种不育是生殖隔离的合子后机制的可能性。另一方面，密集的调查未能在野外发现具有杂交特征的个体，这表明两个物种之间的自然杂交是罕见的。前合子隔离机制，如微生境分离和配子不相容性，至少在Ea卵子和Ec精子之间，最有可能保持这两个密切相关的物种的遗传完整性。
A series of cross-fertilization experiments were conducted with two unnamed, sympatric species of sea urchins in the Echinometra mathaei species complex, Echinometra sp. A (Ea) and Echinometra sp. C (Ec). Heterogametic fertilization success was high when eggs of Ec and sperm of Ea were involved, and low with eggs of Ea and sperm of Ec. Hybrids produced from crosses in either direction developed normally to sexually mature adults; Ea × Ea were largest in test size, followed by Ec (ova) × Ea (sperm), Ea (ova) × Ec (sperm), and Ec × Ec, respectively. Color patterns of the hybrids were closer to the maternal coloration, whereas other characters such as relative test dimensions and spine lengths, morphology of tubefoot and gonad spicules, and gamete sizes were intermediate. Fertilization rates in F1 backcrosses were high, minimizing the possibility that hybrid infertility is a postzygotic mechanism of reproductive isolation. On the other hand, intensive surveys failed to find individuals with hybrid characteristics in the field, suggesting that natural hybridization between the two species is rare. Prezygotic isolating mechanisms, such as microhabitat separation and gamete incompatibility, at least between Ea eggs and Ec sperm, most likely maintain the genetic integrity of these two closely related species.