DISSERTATION RESEARCH: Diversification in Trees of the Lowland Neotropical Rainforest, Based on Studies of the Ubiquitous Legume Swartzia

华盛顿大学的Barbara Schaal博士和Benjamin Torke先生获得了一项赠款，用于研究Swartzia的物种起源和进化关系。Swartzia是一种多样化的热带树木，生长在中南美洲的低地雨林中。在结构、生产力和植物物种丰富度方面，低地热带雨林以树木为主，但热带树木多样性(即遗传和形态差异以及物种起源)的进化机制在很大程度上尚不清楚。各种假说从假设由历史气候和景观变化驱动的物种起源的高比率，到强调现代过渡性栖息地的作用。这项研究将通过确定地理特征的位置(如过渡性生境)与斯瓦茨亚属物种内部和之间遗传和形态变异的空间模式之间的统计相关性来检验对比多样性假说。大部分实地和实验室工作将在巴西东部与巴西圣克鲁斯-巴伊亚大学的安德烈·阿莫林博士密切合作下进行。人为破坏热带雨林和相关的生物多样性丧失是一个国际关注的问题。地球上大约一半的物种生活在热带雨林中。许多植物具有作为食品、药品和建筑材料来源的巨大潜力。有效保护热带雨林需要对产生和维持生物多样性的过程有详细的了解。尽管树木在这些生态系统中作为主要的植物学组成部分具有基础作用，但热带树木的多样性研究很少。历史机制是否足以解释物种多样性，或者现代栖息地的异质性和过渡性栖息地是否有效地维持了物种之间的遗传和形态差异？通过对回答这些问题作出重大贡献，这项研究将对优先保护低地雨林地区以最大限度地保护生物多样性具有重要意义。

A grant has been awarded to Dr. Barbara Schaal and Mr. Benjamin Torke at Washington University to study species origins and evolutionary relationships in Swartzia, a diverse genus of tropical trees that occur in lowland rainforests of Central and South America. In terms of structure, productivity, and botanical species richness, lowland rainforests are dominated by trees, but the evolutionary mechanisms that underlie diversification (i.e., genetic and morphological divergence and species origination) in tropical trees are largely unknown. Hypotheses range from those that postulate high rates of species origination driven by historical climate and landscape changes to those that stress the role of modern transitional habitats. This study will test contrasting diversification hypotheses by identifying statistical correlations between the locations of geographical features, such as transitional habitats, and spatial patterns of genetic and morphological variation within and between species of Swartzia. A significant portion of the field and laboratory work will be carried out in Eastern Brazil in close collaboration with Dr. Andre Amorim of the Universidade Estadual de Santa Cruz-Bahia, Brazil. Human mediated destruction of tropical rainforests and associated loss of biodiversity is a problem of international concern. Approximately half of all species on earth occur in tropical rainforests. Many hold great potential as sources of food, medicine, and building material. Effective conservation of rainforests will require detailed knowledge of the processes that generate and maintain biodiversity. Despite the fundamental role of trees in these ecosystems as the dominant botanical component, diversification has been poorly studied in tropical trees. Are historical mechanisms sufficient to explain species diversity or do modern habitat heterogeneity and transitional habitats effectively maintain genetic and morphological divergences between species? By making significant contributions toward answering these questions, this study will have important implications for prioritizing conservation in lowland rainforest areas to maximize protection of biodiversity