Sesoko Station, Tropical Biosphere Research Center, University of the Ryukyus, Motobu, Okinawa, Japan.
Kuroshio Biological Foundation, Kochi, Japan.
Sci Rep. 2022 Mar 23;12(1):5026. doi: 10.1038/s41598-022-08995-3.
All coral species in the genus Acropora are broadcast-spawning hermaphrodites. Fertilization in the ocean requires sufficient numbers of gametes from conspecifics and the contact time for fertilization is thought to be limited by the rapid diffusion of sperm. Many studies have reported a positive correlation between sperm concentration and fertilization success, but it is not clear how gametes diffuse in seawater to produce mixtures of gametes from many colonies, leading to fertilization that improves genetic diversity. To elucidate this, we analyzed the changes in sperm concentration of A. tenuis in situ after spawning and genotyped sperm and fertilized eggs from seawater using seven microsatellite (MS) markers. Results showed that most of the eggs were fertilized at below 10 sperm/mL in situ. MS genotyping showed that the alleles of released sperm were diverse and those alleles also appeared in the fertilized eggs. The MS fragment peak height in released sperm, which presumably reflects the allele frequency of the sperm, was positively correlated with the allele frequencies of the fertilized eggs. Collectively, synchronous spawning populations composed of highly fecund and genetically diverse colonies potentially increases genetic diversity and the number of descendants.
所有鹿角珊瑚属的物种都是雌雄同体的有性生殖。海洋中的受精需要足够数量的同种配子，并且受精的接触时间被认为受到精子快速扩散的限制。许多研究报告了精子浓度与受精成功率之间的正相关关系，但尚不清楚配子在海水中如何扩散，以产生来自许多珊瑚礁的配子混合物，从而实现提高遗传多样性的受精。为了阐明这一点，我们分析了 A. tenuis 原位产卵后精子浓度的变化，并使用七个微卫星 (MS) 标记对来自海水的精子和受精卵进行了基因分型。结果表明，在原位，大多数卵子在低于 10 个精子/mL 的情况下受精。MS 基因分型表明，释放的精子的等位基因是多样的，并且这些等位基因也出现在受精的卵子中。释放的精子中 MS 片段峰高（大概反映了精子的等位基因频率）与受精卵子的等位基因频率呈正相关。总之，由高繁殖力和遗传多样性的珊瑚礁组成的同步产卵群体可能会增加遗传多样性和后代数量。
