Data from: Niche divergence by deep-sea octocorals in the genus Callogorgia across the continental slope of the Gulf of Mexico

Environmental variables that are correlated with depth have been suggested to be among the major forces underlying speciation in the deep sea. This study incorporated phylogenetics and ecological niche models (ENM) to examine whether congeneric species of Callogorgia (Octocorallia: Primnoidae) occupy different ecological niches across the continental slope of the Gulf of Mexico (GoM), and whether this niche divergence could be important in the evolution of these closely related species. Callogorgia americana americana, C. americana delta, and C. gracilis were documented at 13 sites in the GoM (250-1000 m) from specimen collections and extensive video observations. On a first order, these species were separated by depth, with C. gracilis occurring at the shallowest sites, C. a. americana at mid-depths, and C. a. delta at the deepest sites. Callogorgia a. delta was associated with areas of increased seep activity whereas C. gracilis and C. a. americana were associated with narrow, yet warmer, temperature ranges and did not occur near cold seeps. ENM background and identity tests revealed little to no overlap in ecological niches between species. Temporal calibration of the phylogeny revealed the formation of the Isthmus of Panama was a vicariance event that may explain some of the patterns of speciation within this genus. These results elucidate the potential mechanisms for speciation in the deep sea, emphasizing both bathymetric speciation and vicariance events in the evolution of a genus across multiple regions.

与水深相关的环境变量被认为是深海物种形成的核心驱动因素之一。本研究结合系统发育学与生态位模型（ecological niche models, ENM），旨在探究墨西哥湾（GoM）大陆坡上角珊瑚属（Callogorgia，八放珊瑚亚纲：原珊瑚科）的同属物种是否占据不同生态位，以及该生态位分化对这些近缘物种的演化是否具有关键作用。本研究通过标本采集与大量视频观测，在墨西哥湾13个水深250~1000米的站位记录到美洲角珊瑚美洲亚种（Callogorgia americana americana）、美洲角珊瑚德尔塔亚种（C. americana delta）以及纤细角珊瑚（C. gracilis）。整体而言，这些物种的分布以水深为首要划分依据：纤细角珊瑚分布于最浅站位，美洲角珊瑚美洲亚种分布于中等水深区域，美洲角珊瑚德尔塔亚种则分布于最深站位。美洲角珊瑚德尔塔亚种与渗漏活动增强的区域具有显著相关性，而纤细角珊瑚与美洲角珊瑚美洲亚种则偏好狭窄但温度更高的水温区间，且未在冷泉附近出现。生态位模型背景检验与同一性检验结果显示，各物种间的生态位几乎不存在重叠。系统发育树的时间校准分析显示，巴拿马地峡的形成是一次地理隔离分化事件，该事件或许可以解释该属内部分物种形成的模式。本研究结果阐明了深海物种形成的潜在机制，强调了跨多个区域的属级演化中，水深驱动的物种形成与地理隔离事件的双重作用。