Data from: Sperm dispersal distances estimated by parentage analysis in a brooding scleractinian coral

Within populations of brooding sessile corals, sperm dispersal constitutes the mechanism by which gametes interact and mating occurs, and forms the first link in the network of processes that determine species-wide connectivity patterns. However, almost nothing is known about sperm dispersal for any internally fertilizing coral. In this study, we conducted a parentage analysis on coral larvae collected from an area of mapped colonies, in order to measure the distance sperm disperses for the first time in a reef-building coral and estimated the mating system characteristics of a recently identified putative cryptic species within the Seriatopora hystrix complex (ShA; Warner et al. 2015). We defined consensus criteria among several replicated methods (COLONY 2.0, Cervus 3.0, MLTR v3.2) to maximize accuracy in paternity assignments. Thirteen progeny arrays indicated that this putative species produces exclusively sexually-derived, primarily outcrossed larvae (mean tm=0.999) in multiple paternity broods (mean rp=0.119). Self-fertilization was directly detected at low frequency for all broods combined (2.8%), but comprised 23% of matings in one brood. Although over 82% of mating occurred between colonies within 10 m of each other (mean sperm dispersal = 5.5 m ±4.37 SD), we found no evidence of inbreeding in the established population. Restricted dispersal of sperm compared to slightly greater larval dispersal appears to limit inbreeding among close relatives in this cryptic species. Our findings establish a good basis for further work on sperm dispersal in brooding corals and provide the first information about the mating system of a newly identified and abundant cryptic species.

在育幼型固着珊瑚种群中，精子扩散是配子结合与交配发生的核心机制，亦是调控物种种群连通格局的一系列过程网络的首要环节。然而，目前学界对任何体内受精珊瑚的精子扩散机制仍近乎一无所知。本研究针对从已定位的珊瑚群体采集的幼体开展亲权分析，首次在造礁珊瑚中量化了精子扩散距离，并对近期在柱形珊瑚属（Seriatopora hystrix）复合群中发现的疑似隐存种（ShA；Warner等人，2015年）的交配系统特征进行了估算。我们整合了三种重复验证的分析方法（COLONY 2.0、Cervus 3.0、MLTR v3.2）的共识判定标准，以最大化父权分配的准确性。对13个子代阵列的分析表明，该疑似隐存种仅产生有性生殖来源的幼体，且在多父本育幼群中以异交为主（平均异交率tm=0.999），平均父本亲缘相关性rp=0.119。整体来看，所有育幼群的自交交配占比极低（仅2.8%），但其中一个育幼群的自交交配占比高达23%。尽管超过82%的交配发生在间距10米以内的珊瑚群体之间（平均精子扩散距离为5.5米±4.37标准差），但我们未在已建立的定居种群中检测到近交现象。相较于扩散范围略广的幼体，该隐存种的精子扩散受到显著限制，这一特征似乎限制了近亲间的近交交配。本研究结果为后续开展育幼型珊瑚的精子扩散研究奠定了坚实基础，同时首次为这一新近发现且分布广泛的隐存种提供了其交配系统的相关数据。