Data from: Shared phylogeographical breaks in a Caribbean coral reef sponge and its invertebrate commensals

Aim: To test whether phylogeographical barriers in the brooding sponge Callyspongia vaginalis match breaks previously identified in the Caribbean. We also compared patterns of subdivision in the sponge to those of three of its commensals, the broadcast spawning brittle star Ophiothrix suensonii and the brooding amphipods Leucothoe ashleyae and L. kensleyi, and tested whether any shared breaks arose simultaneously.
Location: Florida, Bahamas and the Caribbean.
Methods: Subdivision of C. vaginalis populations was inferred from one mitochondrial (COI) and six nuclear loci using clustering analyses. We identified phylogeographical breaks in the sponge and its invertebrate commensals by determining geographical patterns of genetic variation and tested simultaneous population divergence across barriers shared among taxa using hierarchical approximate Bayesian computation.
Results: Sponge populations were partitioned into western and eastern groups across the Caribbean, with hierarchical subdivision within regions. The sponge and its commensals shared barriers across their ranges despite differences in dispersal strategy: C. vaginalis, L. ashleyae and O. suensonii populations in Central America were isolated from the remainder of the Caribbean, and all four taxa shared a break between Florida and the Bahamas, although simultaneous population divergence could not be inferred with statistical certainty. Our results also suggest cryptic speciation within C. vaginalis.
Main conclusions: Phylogeographical patterns in C. vaginalis largely matched barriers previously identified at the Florida Straits, Mona Passage and Bay of Honduras in other Caribbean taxa. Oceanographic features such as deep water between locations, strong currents, and eddies are likely mechanisms responsible for these breaks.

研究目的：本研究旨在检验育幼型海绵（brooding sponge）Callyspongia vaginalis的系统地理屏障（phylogeographical barrier）是否与此前在加勒比海区域所识别的断裂带相吻合。此外，本研究还将该海绵的遗传分化格局与其三种偏利共生物种——体外产卵型海蛇尾Ophiothrix suensonii以及育幼型端足类Leucothoe ashleyae和L. kensleyi——的分化格局进行对比，并检验是否存在多类群共享的同步种群分化断裂带。
研究区域：佛罗里达、巴哈马及加勒比海海域。
研究方法：本研究通过对1个线粒体基因座（COI）和6个核基因座开展聚类分析，推断Callyspongia vaginalis的种群遗传分化情况。我们通过解析遗传变异的地理分布模式，识别该海绵及其无脊椎共生物种的系统地理屏障，并采用分层近似贝叶斯计算（hierarchical approximate Bayesian computation）检验多类群是否在共享屏障处发生了同步的种群分化事件。
研究结果：加勒比海区域的Callyspongia vaginalis种群可划分为西部与东部两个群组，且区域内存在层级化的遗传分化结构。尽管各类群的扩散策略存在差异，但该海绵与其共生物种的分布范围内共享了多处遗传屏障：中美洲的C. vaginalis、L. ashleyae与O. suensonii种群与加勒比海其余区域的种群彼此隔离；四类群均在佛罗里达与巴哈马之间存在一处共同的分化断裂带，但无法通过统计学方法确认其种群分化是否为同步发生。此外，本研究结果还暗示Callyspongia vaginalis内部存在隐存物种形成现象。
主要结论：Callyspongia vaginalis的系统地理格局大体与此前在其他加勒比海类群中识别的佛罗里达海峡、莫纳海峡及洪都拉斯湾处的遗传屏障相吻合。海域间的深水环境、强洋流及涡旋等海洋学特征，可能是造成这些地理分化屏障的关键驱动机制。