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先生获得了一笔赠款，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，分布在中美洲和南美洲的低地雨林中。就结构、生产力和植物物种丰富度而言，低地雨林以树木为主，但多样化背后的进化机制（即，遗传和形态分歧和物种起源）在热带树木中很大程度上是未知的。假设范围从那些假定物种起源的历史气候和景观变化的高速率驱动的那些强调现代过渡栖息地的作用。本研究将通过确定地理特征（例如过渡性栖息地）位置之间的统计相关性，以及黑穗病属物种内部和之间的遗传和形态变异的空间模式，来测试对比多样性假设。相当一部分的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Andre Amorim博士密切合作进行。 人类对热带雨林的破坏以及由此造成的生物多样性的丧失是一个国际关注的问题。地球上大约有一半的物种生活在热带雨林中。许多具有巨大的潜力，可作为食物，药物和建筑材料的来源。要有效地保护热带雨林，就必须详细了解产生和维持生物多样性的过程。尽管树木在这些生态系统中作为主要的植物组成部分发挥着重要作用，但对热带树木的多样化研究很少。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？通过对这些问题的回答做出重大贡献，本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产生重要影响

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