Data from: The origin and evolution of coral species richness in a marine biodiversity hotspot

The Coral Triangle region of the Indo-Pacific realm harbors an extraordinary number of species, with richness decreasing away from this biodiversity hotspot. Despite multiple competing hypotheses, the dynamics underlying this regional diversity pattern remain poorly understood. Here we use a time-calibrated evolutionary tree of living reef coral species, their current geographic ranges, and model-based estimates of regional rates of speciation, extinction, and geographic range shifts to show that origination rates within the Coral Triangle are lower than in surrounding regions, a result inconsistent with the long-standing center of origin hypothesis. Furthermore, endemism of coral species in the Coral Triangle is low, and the Coral Triangle endemics are older than relatives found outside this region. Overall, our model results suggest that the high diversity of reef corals in the Coral Triangle is largely due to range expansions into this region of species that evolved elsewhere. These findings strongly support the notion that geographic range shifts play a critical role in generating species diversity gradients. They also show that preserving the processes that gave rise to the striking diversity of corals in the Coral Triangle requires protecting not just reefs within the hotspot, but also those in the surrounding areas.

印太生物地理域（Indo-Pacific realm）的珊瑚三角区（Coral Triangle）栖息着数量极为可观的物种，物种丰富度随远离该生物多样性热点区域而逐渐降低。尽管已提出多种相互竞争的假说，但该区域物种多样性格局背后的动态机制仍未得到充分阐释。本研究利用现生礁珊瑚物种的时间校准进化树（time-calibrated evolutionary tree）、当前地理分布范围，以及基于模型估算的区域物种形成（speciation）、灭绝（extinction）与地理分布迁移（geographic range shifts）速率，证明珊瑚三角区内的物种起源速率低于周边区域——这一结果与长期流行的起源中心假说（center of origin hypothesis）相悖。此外，珊瑚三角区内的珊瑚物种特有性水平较低，且该区域的特有物种的演化年代比区域外的近缘物种更古老。综合来看，我们的模型结果表明，珊瑚三角区内礁珊瑚的高物种多样性，主要源于在其他区域演化形成的物种向该区域的分布扩张。这些发现有力支持了"地理分布迁移在塑造物种多样性格局梯度中发挥关键作用"这一观点。研究同时表明，若要保护造就珊瑚三角区惊人珊瑚多样性的生态过程，不仅需要保护该热点区域内的珊瑚礁，还需兼顾周边区域的珊瑚礁。