New species of closely related endosymbiotic dinoflagellates in the Greater Caribbean have niches corresponding to host coral phylogeny

Symbiotic dinoflagellates in the genus Breviolum (formerly Symbiodinium Clade B) dominate coral communities in shallow waters across the Greater Caribbean. While some formally described species exist, mounting genetic, and ecological evidence indicate that numerous more comprise this genus, many of which are closely related. To test this, colonies of common reef‐building corals were sampled across a large geographical range. Phylogenetic and population genetic markers then used to examine evolutionary divergence and delineate boundaries of genetic recombination. Three new candidate species were distinguished by fixed differences in nucleotide sequences from nuclear and chloroplast DNA. Population connectivity was evident within each lineage over thousands of kilometers, however, substantial genetic structure persisted between lineages co‐occurring within sampling locations, signifying reproductive isolation. While geographically widespread with overlapping distributions, each species is...

短甲藻属（Breviolum，原称虫黄藻B分支）的共生双鞭毛虫（Symbiotic dinoflagellates）主导了大加勒比地区浅水环境中的珊瑚群落。尽管该属已有部分正式定名的物种，但越来越多的遗传学与生态学证据表明，该属还包含大量亲缘关系紧密的类群。为验证这一结论，研究团队在大范围地理区域内采集了常见造礁珊瑚的共生体样本。随后通过系统发育与群体遗传学标记，分析其演化分化并界定遗传重组的边界。通过核DNA与叶绿体DNA核苷酸序列的固定差异，研究人员区分出3个新的候选物种。尽管每个谱系在数千公里范围内均表现出种群连通性，但在同一采样点内共存的不同谱系之间仍存在显著的遗传结构，这意味着它们存在生殖隔离。虽然这些物种地理分布广泛且存在分布重叠，但每个物种均……