Data from: Historical biogeography of endemic seed plant genera in the Caribbean: did GAARlandia play a role?

The Caribbean archipelago is a region with an extremely complex geological history and an outstanding plant diversity with high levels of endemism. The aim of this study is to better understand the historical assembly and evolution of endemic seed plant genera in the Caribbean, by first determining divergence times of endemic genera to test whether the hypothesized Greater Antilles and Aves Ridge (GAARlandia) land bridge played a role in the archipelago colonization, and second by testing South America as the main colonization source as expected by the position of landmasses and recent evidence of an asymmetrical biotic interchange. We reconstructed a dated molecular phylogenetic tree for 625 seed plants including 32 Caribbean endemic genera using Bayesian inference and ten calibrations. To estimate the geographic range of the ancestors of endemic genera we performed a model selection between a null and 2 complex biogeographical models that included timeframes based on geological information, dispersal probabilities and directionality among regions. Crown ages for endemic genera ranged from Early Eocene (53.1 Ma) to Late Pliocene (3.4 Ma). Confidence intervals for divergence times (crown and/or stem ages) of 22 endemic genera occurred within the GAARlandia time frame. Contrary to expectations, the Antilles appears as the main ancestral area for endemic seed plant genera and only five genera had a South American origin. In contrast with patterns shown for vertebrates and other organisms and based on our sampling we conclude that GAARlandia did not act as a colonization route for plants between South America and the Antilles. Further studies on Caribbean plant dispersal at the species and population levels will be required to reveal finer-scale biogeographic patterns and mechanisms.

加勒比群岛拥有极为复杂的地质历史与极高的植物多样性，且特有性水平显著。本研究旨在更深入地解析加勒比地区特有种子植物属的历史组装与演化过程，具体通过两项研究达成：其一，测定特有属的分化时间，以验证假说中的大安的列斯群岛与艾夫斯脊（Greater Antilles and Aves Ridge, GAARlandia）陆桥是否在群岛殖民过程中起到了作用；其二，验证南美洲是否为主要的殖民来源地——该推论基于陆块的地理位置以及近期发现的不对称生物互换证据。本研究采用贝叶斯推断（Bayesian inference）与10个校准位点，对包含32个加勒比特有属在内的625种种子植物构建了定年分子系统发育树。为估算特有属祖先的地理分布范围，我们在零模型与2种复杂生物地理模型之间开展了模型选择；这些复杂模型以地质信息、区域间扩散概率与方向性为依据设置了时间框架。特有属的冠群年龄范围为始新世早期（53.1 Ma）至上新世晚期（3.4 Ma）。22个特有属的分化时间（冠群年龄和/或茎群年龄）置信区间处于GAARlandia的存续时间范围内。与预期相悖的是，安的列斯群岛是特有种子植物属的主要祖先分布区，仅5个属起源于南美洲。结合本研究的采样结果，与脊椎动物及其他类群的研究模式相反，我们得出结论：GAARlandia并未作为南美洲与安的列斯群岛之间的植物殖民通道发挥作用。后续需在物种与种群水平上开展加勒比植物扩散相关研究，以揭示更精细尺度下的生物地理模式与形成机制。