Dissertation Research: Systematics of Erythrina (Leguminosae) and the Evolution of Pollination Systems

在教授导师Jeffrey Doyle博士的指导下，康奈尔大学的研究生Anne Bruneau将研究豆科植物刺桐属物种的分子系统学、形态和授粉生物学。有几种树种在热带地区作为行道树种植，用作活栅栏，或在咖啡和可可种植园作为遮荫树种植。所有刺桐属物种都有红色或橙色的花，由蜂鸟或栖息鸟(雀形目)授粉。由栖息鸟类授粉的物种具有宽大的、张开的花朵，这些花朝向树枝或树枝尖端；由蜂鸟授粉的物种具有向外的窄管状花朵，只有盘旋的鸟类才能获得花蜜，从而实现授粉。蜂鸟授粉被认为比栖息鸟类授粉更专业，但这从来没有经过严格的测试。相当大的生物学和园艺兴趣导致了该属几乎所有112种物种都可以在活的收藏品中获得。实验室工作将重点放在物种多样性的分子标记上，这些标记是通过分析叶绿体DNA和核糖体DNA获得的。结合分子和形态证据将为该群体产生一个强大的系统发育树。田野工作将记录那些尚未研究的剩余物种的特定传粉者。然后，研究人员可以确定蜂鸟和栖息鸟类授粉物种之间的进化关系，并测试这种物种之间的进化变化是一次还是多次。

Under the guidance of faculty adviser Dr. Jeffrey Doyle, graduate student Anne Bruneau of Cornell University will study the molecular systematics, morphology, and pollination biology of species in the legume genus Erythrina. Several species are cultivated as street trees in the tropics, used as living fences, or planted as shade trees in coffee and cacao plantations. All Erythrina species have red or orange flowers and are pollinated by either hummingbirds or perching birds (order Passeriformes). Species pollinated by perching birds have wide, gaping flowers that are oriented toward branches or branch tips; species pollinated by hummingbirds have narrow-tubed flowers that face outwards and only birds that hover can obtain nectar, and thereby effect pollination. Hummingbird pollination has been considered more specialized than pollination by perching birds, but this has never been critically tested. Considerable biological and horticultural interest has resulted in the availability of nearly all 112 species in the genus in living collections. Laboratory work will focus on molecular markers of species diversification, obtained from analyses of chloroplast DNA and nuclear ribosomal DNA. Combined molecular and morphological evidence will produce a robust phylogenetic tree for the group. Field work will document the specific pollinators of those remaining species not yet studied. The researchers can then determine the evolutionary relationships between hummingbird- and perching bird-pollinated species and test whether the evolutionary change occurred once or several times among species of this genus.