Ricardo Gerard F, Doropoulos Christopher, Babcock Russell C, Adam Arne A S, Buccheri Elizabeth, Robledo Natalia, Uribe-Palomino Julian, Mumby Peter J
Marine Spatial Ecology Lab School of the Environment, The University of Queensland St. Lucia Queensland Australia.
CSIRO Environment St. Lucia Queensland Australia.
Ecol Evol. 2025 Jun 26;15(7):e71654. doi: 10.1002/ece3.71654. eCollection 2025 Jul.
Understanding strategies of organisms that utilise multiple modes of reproduction presents a complex challenge for evolutionary biologists. The genus , a common reef-building coral with unclear reproductive boundaries among morphological species, illustrates these complexities. Here, we evaluate the contribution of different reproductive modes in the coral at Heron Island, on the southern Great Barrier Reef, during the less prominent phase of a split-spawning event, enabling assessment of reproductive outcomes associated with low population densities. We tagged and sequenced eighteen coral colonies, representing varying degrees of spatial clustering, along a 130-m stretch of shallow reef slope. During spawning, divers trapped eggs from monitored colonies in mesh containers, which were then released into the surrounding water. High levels of spawning asynchrony were observed, potentially indicating distinct genetic clusters within the putative species, resulting in low fertilisation success (1.5%). Notably, paternity assignments revealed all resulting embryos were self-fertilised, with no cross-fertilisation detected, suggesting that self-fertilisation may serve as a reproductive assurance mechanism in during these smaller spawning events. The adult population showed evidence of two genetically distinct subpopulations, along with spatial autocorrelation and inbreeding. This supports the existence of smaller breeding units within larger assemblages, density-dependent population effects and localised recruitment, indicating that these populations may be more hierarchically structured than previously recognised. Given the lack of evidence for in situ outcrossed fertilisation in this natural coral population during a minor spawning event, it appears that may utilise atypical modes of reproduction at low densities as observed here and/or alternatively rely on higher-density spawning events and favourable hydrodynamic features not captured in this study.
对于进化生物学家而言，理解利用多种繁殖方式的生物体的策略是一项复杂的挑战。鹿角珊瑚属是一种常见的造礁珊瑚，其形态物种间的繁殖界限不明确，就说明了这些复杂性。在这里，我们评估了大堡礁南部赫伦岛鹿角珊瑚在分裂产卵事件不太显著阶段不同繁殖方式的贡献，从而能够评估与低种群密度相关的繁殖结果。我们沿着130米长的浅礁斜坡标记并测序了18个珊瑚群落，这些群落代表了不同程度的空间聚集。在产卵期间，潜水员将监测群落的卵捕获到网箱中，然后将其释放到周围水中。观察到高水平的产卵异步性，这可能表明在假定物种内存在不同的基因簇，导致受精成功率较低（1.5%）。值得注意的是，父系分析表明所有产生的胚胎都是自体受精的，未检测到异体受精，这表明在这些较小的产卵事件中，自体受精可能是鹿角珊瑚的一种繁殖保障机制。成年种群显示出两个基因上不同的亚种群的证据，以及空间自相关和近亲繁殖现象。这支持了在较大群体中存在较小繁殖单元、密度依赖性种群效应和局部补充的观点，表明这些种群的结构可能比以前认识的更加分层。鉴于在这次小规模产卵事件中，这个自然珊瑚种群缺乏原地异体受精的证据，可以看出鹿角珊瑚可能会像这里观察到的那样在低密度时利用非典型的繁殖方式，和/或依赖于更高密度的产卵事件以及本研究未捕捉到的有利水动力特征。
