Origin and Evolution of Endemic Asteraceae From the Macaronesian Archipelagos

9707614 Jansen与国外同事dr。德克萨斯大学的Robert Jansen博士正在马卡尼西亚群岛、加那利群岛、马德拉群岛和亚速尔群岛上研究向日葵近亲——菊科的几个属的系统发育和生物地理学。超过800种植物被描述为这些岛屿特有的（在其他地方找不到），其中25%属于菊科，这表明岛屿之间和单个岛屿海拔上的进化辐射实例。来自叶绿体和核基因DNA测序的新证据，来自岛屿物种样本以及来自怀疑有亲缘关系的非洲和地中海物种的同事提供的标本，将有助于为Argyranthemum、Cheirolophus、Pericallis和Tolpis等属构建系统发育树或系谱。在该属存在现代专著处理的地方，例如对银菊花，可以将分子证据与所有物种的形态特征相结合，以评估物种间在选择花和营养特征方面的变化率和模式。对Cheirolophus （Cardueae部落）、Pericallis （Senecioneae部落）和Tolpis （Lactuceae部落）的系统发育研究将有助于在世界范围内确定向日葵科这些大亚群的系统发育树结构。人们提出了许多相互冲突或重叠的理论来解释马卡罗尼西亚岛上特有物种的数量和分布，但没有一个很好的支持系统发育框架来指导关于进化和迁移的假设，理论化可能会继续不受限制。非洲大陆或地中海地区是否成为马卡罗尼西亚移民的来源地，是否可能发生过回迁，是否单个或少数移民产生了许多新物种，而不是从大陆来源地大量引进，创造了岛屿的多样性，物种形成是发生在岛屿之间还是发生在个别山地岛屿的高程带之间？所有这些生物地理学问题都可以在一个得到有力支持的系统发育框架内进行研究。

9707614 Jansen In collaboration with foreign colleagues Drs. Javier Francisco-Ortega and Arnoldo Santos-Guerra, Dr. Robert Jansen of the University of Texas is studying the phylogeny and biogeography of several genera of sunflower relatives, family Asteraceae, on the islands of the Macaronesian archipelago, the Canaries, Madeiras, and Azores. Over 800 species of plants have been described that are endemic to these islands (found nowhere else), and 25% of these belong to the family Asteraceae, which shows instances of evolutionary radiation both among islands and elevationally on single islands. New evidence from DNA sequencing of chloroplast and nuclear genes, from samples of island species and from collections provided by colleagues from African and Mediterranean species suspected to be related, will help construct phylogenetic trees or genealogies for such genera as Argyranthemum, Cheirolophus, Pericallis, and Tolpis. Where modern monographic treatments exist of the genera, such as for Argyranthemum, the molecular evidence can be integrated with morphological characters described for all the species, to assess rates and patterns of change among species in select floral and vegetative features. The phylogenetic studies on Cheirolophus (tribe Cardueae), Pericallis (tribe Senecioneae), and Tolpis (tribe Lactuceae) will contribute to nascent efforts to determine the phylogenetic tree structure for these large subgroups of the sunflower family on a world-wide basis. Numerous conflicting or overlapping theories have been proposed to explain the number and distribution of endemic species on the Macaronesian islands, but without a well supported phylogenetic framework to guide hypotheses about evolution and migration, the theorizing may continue unconstrained. Whether the African mainland or Mediterranean regions have served as sources for migrants to Macaronesia, whether back migration may have occurred, whether single or few migrants radiated into numerous new species as opposed to multiple in troductions from continental sources creating the diversity of the islands, whether speciation has occurred more often between islands or between elevation zones on individual mountainous islands_all these questions of biogeography can be studied within a robustly supported phylogenetic framework of the several groups of plants under consideration.