Department of Biology and Burke Museum, University of Washington, Seattle, Washington, 98195 USA.
Instituto de Botánica Darwinion, Labardén 200, San Isidro, Argentina.
Am J Bot. 2017 Nov;104(11):1708-1716. doi: 10.3732/ajb.1700292.
Verbenaceae originated and initially diversified in South America in wet forest habitats. They have diversified extensively in arid habitats in both South and North America. This study aims to understand the origin of the North American arid-land members of Verbenaceae.
A phylogenetic approach is used to examine four genera (Aloysia, Citharexylum, Glandularia, Verbena) in three distinct clades with representatives in North American deserts and disjunct South and North American distributions. Phylogenetic analyses were conducted using maximum likelihood and Bayesian approaches. Analyses included both plastid and nuclear DNA regions and include the first study of Citharexylum and an expanded sampling of tribe Verbeneae (Glandularia and Verbena). Ancestral areas were reconstructed for each group.
North American desert species of Aloysia and Glandularia were likely derived from ancestors in arid temperate South America, perhaps by long-distance dispersal. The pattern for Verbena was less clear, with evidence from plastid DNA implicating an Andean dispersal route to the North American clade, whereas nuclear data suggest that the Andean and North American species resulted from independent dispersals from southern South America. A previously unrecognized clade of Andean Verbeneae was discovered, raising the possibility of an Andean origin of Verbena or Verbena and Glandularia. North American desert species of Citharexylum represent multiple, independent origins from mesic habitat ancestors in Mesoamerica.
North American arid-zone Verbenaceae are derived from South and Central American ancestors via multiple avenues, including long-distance, amphitropical dispersal, Andean migration corridors, and in situ evolution of desert-adapted species.
马鞭草科起源于南美的湿润森林生境，并最初在那里多样化。它们在南、北美洲的干旱生境中广泛多样化。本研究旨在了解马鞭草科北美干旱区成员的起源。
采用系统发育方法研究了四个属（Aloysia、Citharexylum、Glandularia、Verbena），它们在三个不同的分支中具有北美沙漠和南北美间断分布的代表。系统发育分析采用最大似然法和贝叶斯法进行。分析包括质体和核 DNA 区域，包括对 Citharexylum 的首次研究以及对 Verbeneae 族（Glandularia 和 Verbena）的扩展采样。为每个组重建了祖先区域。
北美沙漠种 Aloysia 和 Glandularia 可能源自干旱温带南美祖先，可能通过远距离散布而来。Verbena 的模式则不太清楚，质体 DNA 的证据表明有一条安第斯散布途径到达北美分支，而核数据表明，安第斯和北美物种是由来自南美的南部的独立散布而来。发现了一个以前未被识别的安第斯 Verbeneae 分支，这增加了 Verbena 或 Verbena 和 Glandularia 起源于安第斯的可能性。北美沙漠种 Citharexylum 代表了从中美洲湿润生境祖先通过多种途径独立起源的多个物种。
北美干旱区马鞭草科是通过多种途径从南美和中美洲祖先衍生而来的，包括远距离、泛热带散布、安第斯迁徙走廊和适应沙漠的物种的原地进化。
