Tel Aviv University, School of Zoology, Tel Aviv, 6997801, Israel.
The Interuniversity Institute for Marine Sciences, P.O. Box 469, Eilat, 8810369, Israel.
Sci Rep. 2019 Feb 27;9(1):2936. doi: 10.1038/s41598-018-37619-y.
Sex change has been widely studied in animals and plants. However, the conditions favoring sex change, its mode and timing remain poorly known. Here, for the first time in stony corals, we report on a protandrous (youngest individuals are males) repetitive sex change exhibited by the fungiid coral Herpolitha limax across large spatial scales (the coral reefs of Japan, Jordan and Israel) and temporal scales (2004-2017). In contrast to most corals, this species is a daytime spawner (08:00-10:00 AM) that spawned at the same time/same date across all the study sites. The sporadically scattered populations of H. limax among the coral reefs of Eilat (Israel) and Aqaba (Jordan) exhibited significantly slower growth, earlier sex change, and lower percentages of reproduction and sex change in comparison to the densely aggregated populations in Okinawa (Japan). At all sites, sex ratio varied among years, but was almost always biased towards maleness. Growth rate decreased with size. We conclude that comparable to dioecious plants that display labile sexuality in response to energetic and/or environmental constraints, the repetitive sex change displayed by H. limax increases its overall fitness reinforcing the important role of reproductive plasticity in the Phylum Cnidaria in determining their evolutionary success.
性转变在动植物中已得到广泛研究。然而，有利于性转变的条件、其模式和时间仍然知之甚少。在这里，我们首次在石珊瑚中报告了真菌珊瑚 Herpolitha limax 在大空间尺度（日本、约旦和以色列的珊瑚礁）和时间尺度（2004-2017 年）上表现出的雄先熟（最年轻的个体是雄性）的重复性别转变。与大多数珊瑚不同，该物种是白天产卵者（上午 8:00-10:00），在所有研究地点都在同一时间/同一日期产卵。埃拉特（以色列）和亚喀巴（约旦）珊瑚礁中零星分散的 H. limax 种群的生长速度明显较慢，性转变更早，繁殖和性转变的百分比也较低，与冲绳（日本）密集聚集的种群相比。在所有地点，性别比例随年份而变化，但几乎总是偏向雄性。生长速度随体型减小而降低。我们得出结论，与表现出对能量和/或环境限制具有易变性别特征的雌雄异株植物类似，H. limax 表现出的重复性别转变增加了其整体适应性，增强了生殖可塑性在腔肠动物门中的重要作用，以确定它们的进化成功。
