Dissertation Reserch: The Maintenance of a Genetic Color Polymorphism in the Mosquitofish, Gambushia Holbrooki

9902312 Travis Horth本项目的目标是确定一种罕见的，遗传控制的，雄性体色模式变体是如何在许多食蚊鱼，Gambusia holbrooki的自然种群中保持的。这种持久性是惊人的，因为雄性只有一个决定颜色的基因拷贝，理论表明这种类型的变异不应该在自然界中持续存在。 这项研究将涉及：（1）水温如何影响体色的表达，从而掩盖导致黑变的基因，使银色雄性显得比实际上更常见;（2）银色雄性和黑变雄性如何相互作用，以及如何与雌性相互作用;（3）当银色和黑色雄性竞争雌性时，它们所生后代的数量是否不同，使用行为观察和受控的遗传杂交。这项研究解决了理论和经验模式之间的根本差距。 从理论上讲，单拷贝基因或单倍体在自然界中不应该表现出太多的遗传变异;在实践中，像这样的变异很常见。 它还解决了自然遗传变异的一个新特征，即温度依赖性表达，以及该表达是否实际上掩盖了比明显更多的遗传变异。 遗传变异在不同热环境中的表达方式是理解动物如何应对全球变化的关键问题，以及这种反应是仅仅是生态学的还是进化的。H：\popbio\abstracts\fy1999\9902312（Travis摘要）

9902312Travis & HorthThe goal of this project is to identify how a rare, genetically controlled, male body color pattern variant is maintained in many natural populations of mosquitofish, Gambusia holbrooki. This persistence is striking because males have only a single copy of the color-determining gene and theory suggests that this type of variation should not readily persist in nature. This study will address: (1) how water temperature may affect the expression of body color so as to mask the gene that causes melanism and make silver males appear more common than they really are; (2) how silver and melanic males interact with each other and with females; and (3) whether silver and melanic males differ in the number of offspring they sire when they compete for females, using behavioral observations and controlled genetic crosses. The study addresses a fundamental gap between theory and empirical pattern. In theory, single-copy genes, or haploids, ought not to exhibit much genetic variation in nature; in practice, variations like this one are common. It also addresses a novel feature of natural genetic variation, that of temperature-dependent expression and whether that expression is actually masking more genetic variation than is apparent. The way in which genetic variation is expressed in different thermal environments is a key issue in understanding how animals will respond to global change and whether that response will be merely ecological or also evolutionary. H:\popbio\abstracts\fy1999\9902312 (Travis abstract)