Martín-Bravo Santiago, Daniel Thomas F
Botany Area, Department of Molecular Biology and Biochemical Engineering, Universidad Pablo de Olavide, ctra. de Utrera km 1, ES-41013, Seville, Spain Department of Botany, California Academy of Sciences, 55 Music Concourse Drive, Golden Gate Park, San Francisco, California 94118 USA
Department of Botany, California Academy of Sciences, 55 Music Concourse Drive, Golden Gate Park, San Francisco, California 94118 USA.
Am J Bot. 2016 Jun;103(6):1103-16. doi: 10.3732/ajb.1600083. Epub 2016 Jun 16.
Barleria is a large, pantropical genus of ca. 265 species mainly distributed in the Old World with only one species, B. oenotheroides, extending to the neotropics. This amphi-Atlantic disjunction, frequently displayed by pantropical taxa, has been traditionally explained with vicariance or geodispersal hypotheses and increasingly with long-distance dispersal. The native status of this species in the New World is controversial.
A molecular phylogeographic study based on the nuclear ribosomal ITS region and plastid trnL-F, rps16, and trnS-G sequences was done to clarify the origin of this tropical intercontinental disjunction. Divergence times were estimated with various analytical approaches, including different markers and primary calibration points.
Divergence ages estimated for Barleria lineages disagree with vicariance or geodispersal hypotheses. Genetic differentiation of American vs. African populations of B. oenotheroides does not support a recent anthropogenic introduction to the New World. Our data suggest ancient long-distance dispersal from the Old to the New World probably during the Pliocene or Upper Miocene. The number of dispersal events remains unclear.
Our study demonstrates the native status of Barleria in the New World, resolving one of only three presumed natural Old World-New World disjunctions at the species level among Acanthaceae. This case constitutes a further documented example of the "out-of-Africa" pattern in the family, despite their lack of documented assisted-dispersal syndromes, and highlights the importance of long-distance dispersal to explain pantropical distributions in many families.
假杜鹃属是一个分布于泛热带地区的大属，约有265个物种，主要分布在东半球，只有一种——柳叶菜状假杜鹃延伸至新热带地区。这种跨大西洋间断分布，在泛热带类群中很常见，传统上用隔离分化或地质扩散假说来解释，现在越来越多地用远距离扩散来解释。该物种在新世界的原生状态存在争议。
基于核糖体ITS区域以及叶绿体trnL-F、rps16和trnS-G序列开展了分子系统地理学研究，以阐明这种热带洲际间断分布的起源。采用多种分析方法估算分歧时间，包括不同的标记和主要校准点。
假杜鹃谱系的分歧时间估计与隔离分化或地质扩散假说不一致。柳叶菜状假杜鹃美洲种群与非洲种群的遗传分化不支持其近期人为引入新世界的观点。我们的数据表明，可能在上新世或中新世晚期发生了从旧世界到新世界的古老远距离扩散。扩散事件的数量仍不清楚。
我们的研究证明了假杜鹃在新世界的原生状态，解决了爵床科中仅有的三个假定的自然东半球-西半球物种水平间断分布之一。尽管缺乏有记录的辅助扩散综合征，但这个案例构成了该科“走出非洲”模式的又一个有记录的例子，并强调了远距离扩散对解释许多科的泛热带分布的重要性。
