DISSERTATION RESEARCH: Geographic Variation in Pollinators, Outcrossing, and the Incipient Evolution of Dioecy in Echinocereus coccineus (Cactaceae)

论文研究：Echinocereus coccineus（仙人掌科）传粉者的地理变异、异型杂交和雌雄异株的早期进化

• 批准号: 0412663
• 负责人: Theodore Fleming
• 金额: $ 1.2万
• 依托单位: University of Miami
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-05-15 至 2005-04-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0412663&HistoricalAwards=false
• 关键词: DISSERTATION; RESEARCH; Geographic; Variation; Pollinators

One of the fundamental questions in biology is: Why have separate sexes? Having separate sexes avoids the worst type of inbreeding: self-fertilization. In animal-pollinated plants it is hypothesized that separate sexes evolve in certain areas (e.g., mountain-tops, deserts) because the less specialized pollinators there predominantly self-fertilize these plants. An alternative hypothesis is separate sexes evolve because resources (e.g., water) needed for sexual function are scarce, and can be allocated more efficiently if the sexes are separated. Claret-cup cacti present a unique opportunity to concurrently test these two hypotheses because they possess both hermaphroditic (sexes together) and dioecious (sexes separated) populations. This species is pollinated by less-specialized bees in and around dioecious populations, which supports the inbreeding-avoidance hypothesis. However, dioecious populations also tend to occur in arid areas. This supports the resource-allocation hypothesis. Genetic analyses at the plant, population and landscape scale will determine if the rate of self-fertilization produced by bees is sufficient to produce dioecy. The direct and indirect effects of pollinators, rainfall and other environmental factors on the evolution of dioecy will be assessed using Structural Equation Modeling. Funding of this research will provide the first test of the inbreeding-avoidance hypothesis in natural populations. Developing the first microsatellite markers for cacti for this project has led to collaborations across three institutions and training of minority undergraduates in modern genetic techniques.

生物学中的基本问题之一是：为什么有单独的性别？独立的性别避免了最糟糕的近亲繁殖类型：自我育种。在动物授粉的植物中，假设在某些地区（例如，山顶，沙漠）中分开的性别会发展，因为那里的专业授粉媒介主要少于自我受精。另一种假设是分开的性别发展，因为性功能所需的资源（例如，水）很少，如果性别分开，则可以更有效地分配。 Claret-Cup Cacti提供了一个独特的机会，可以同时检验这两个假设，因为它们既有雌雄同体（性别）和外外（性别分开）的人群。该物种在富裕人群中及其周围的蜜蜂受授粉，这支持了近亲避免避免假说。但是，尤其人群也倾向于在干旱地区发生。这支持资源分配假设。植物，种群和景观量表的遗传分析将确定蜜蜂产生的自我施用率是否足以产生二元。授粉媒介，降雨和其他环境因素对二元发展的发展的直接和间接影响将使用结构方程建模进行评估。这项研究的资金将提供自然种群中近亲繁殖假设的首次测试。为该项目开发了仙人掌的第一个微卫星标记，这导致了三个机构的合作，并在现代遗传技术中培训了少数族裔本科生。