Diversification dynamics in the Neotropics through time, clades and biogeographic regions

The origins and evolution of the outstanding Neotropical biodiversity are a matter of intense debate. A comprehensive understanding is hindered by the lack of deep-time comparative data across wide phylogenetic and ecological contexts. Here, we quantify the prevailing diversification trajectories and drivers of Neotropical diversification in a sample of 150 phylogenies (12,512 species) of seed plants and tetrapods and assess their variation across Neotropical regions and taxa. Analyses indicate that Neotropical diversity has mostly expanded through time (70% of the clades), while scenarios of saturated and declining diversity account for 21% and 9% of Neotropical diversity, respectively. Five biogeographic areas are identified as distinctive units of long-term Neotropical evolution, including Pan-Amazonia, the Dry Diagonal, and Bahama-Antilles. Diversification dynamics do not differ across these areas, suggesting no geographic structure in long-term Neotropical diversification. In contrast, diversification dynamics differ across taxa: plant diversity mostly expanded through time (88%), while a substantial fraction (43%) of tetrapod diversity accumulated at a slower pace or declined toward the present. These opposite evolutionary patterns may reflect different capacities for plants and tetrapods to cope with past climate changes

新热带区生物多样性（Neotropical biodiversity）的起源与演化，长期以来都是学界激烈争论的核心议题。由于缺乏覆盖广泛系统发育与生态背景的深时比较数据，学界对其形成机制的全面理解受到了严重阻碍。
本研究针对涵盖12512个物种的150组种子植物与四足动物（tetrapods）系统发育树（phylogenies）样本开展量化分析，厘清了新热带区物种多样化的主流轨迹与驱动因素，并评估了其在新热带区不同区域与类群间的变异特征。
分析结果显示，新热带区的生物多样性大多随时间推移持续扩张（占全部演化支（clades）的70%），而饱和型与衰退型多样性场景分别占新热带区生物多样性的21%与9%。
研究识别出五个具备独特长期演化特征的新热带区生物地理单元，包括泛亚马逊区、干旱对角带（Dry Diagonal）以及巴哈马-安的列斯群岛区。不同区域间的多样化动态并无显著差异，这表明新热带区的长期多样化进程不存在地理结构分化。
与之形成鲜明对比的是，不同类群间的多样化动态存在显著差异：植物类群的多样性大多随时间持续扩张（占比88%），而四足动物类群中有相当比例（43%）的多样性以较慢速率积累，甚至在临近现代时出现衰退。
这类截然相反的演化模式，可能反映了种子植物与四足动物应对过去气候变化的能力存在显著差异。