Drury Crawford, Pérez Portela Rocío, Serrano Xaymara M, Oleksiak Marjorie, Baker Andrew C
Department of Marine Biology and Ecology Rosenstiel School of Marine and Atmospheric Science University of Miami Miami Florida.
Present address: Hawai'i Institute of Marine Biology University of Hawai'i at Mānoa Kāne'ohe Hawai'i.
Ecol Evol. 2020 May 20;10(12):6009-6019. doi: 10.1002/ece3.6340. eCollection 2020 Jun.
Mesophotic reefs (30-150 m) have been proposed as potential refugia that facilitate the recovery of degraded shallow reefs following acute disturbances such as coral bleaching and disease. However, because of the technical difficulty of collecting samples, the connectivity of adjacent mesophotic reefs is relatively unknown compared with shallower counterparts. We used genotyping by sequencing to assess fine-scale genetic structure of at two sites at Pulley Ridge, a mesophotic coral reef ecosystem in the Gulf of Mexico, and downstream sites along the Florida Reef Tract. We found differentiation between reefs at Pulley Ridge (~68 m) and corals at downstream upper mesophotic depths in the Dry Tortugas (28-36 m) and shallow reefs in the northern Florida Keys (Key Biscayne, ~5 m). The spatial endpoints of our study were distinct, with the Dry Tortugas as a genetic intermediate. Most striking were differences in population structure among northern and southern sites at Pulley Ridge that were separated by just 12km. Unique patterns of clonality and outlier loci allele frequency support these sites as different populations and suggest that the long-distance horizontal connectivity typical of shallow-water corals may not be typical for mesophotic systems in Florida and the Gulf of Mexico. We hypothesize that this may be due to the spawning of buoyant gametes, which commits propagules to the surface, resulting in greater dispersal and lower connectivity than typically found between nearby shallow sites. Differences in population structure over small spatial scales suggest that demographic constraints and/or environmental disturbances may be more variable in space and time on mesophotic reefs compared with their shallow-water counterparts.
中光层珊瑚礁（30 - 150米）被认为是潜在的避难所，有助于退化的浅海珊瑚礁在诸如珊瑚白化和疾病等急性干扰后恢复。然而，由于采集样本存在技术困难，与较浅的珊瑚礁相比，相邻中光层珊瑚礁的连通性相对未知。我们利用测序基因分型技术，评估了墨西哥湾一个中光层珊瑚礁生态系统——滑轮岭的两个地点以及佛罗里达礁区下游地点的精细遗传结构。我们发现，滑轮岭（约68米）的珊瑚礁与德赖托图格斯群岛下游中光层较深区域（28 - 36米）以及佛罗里达群岛北部浅海珊瑚礁（比斯坎湾，约5米）的珊瑚之间存在差异。我们研究的空间端点各不相同，德赖托图格斯群岛是遗传中间地带。最显著的是，滑轮岭南北部仅相隔12公里的地点之间的种群结构存在差异。独特的克隆模式和异常位点等位基因频率支持这些地点属于不同种群，并表明浅水珊瑚典型的长距离水平连通性可能并非佛罗里达和墨西哥湾中光层系统的典型特征。我们推测，这可能是由于浮力配子的产卵，使繁殖体浮向水面，导致扩散范围更大，连通性低于附近浅海地点之间通常的情况。小空间尺度上种群结构的差异表明，与浅水珊瑚礁相比，中光层珊瑚礁上的人口统计学限制和/或环境干扰在空间和时间上可能更具变异性。
