Dissertation Research: Systematics, Secondary reproductive characteristics, and Biogeography of the Poeciliid Fish genus Limia

0073231斯普林格和汉密尔顿利米亚是加勒比海淡水鱼的一个属，与孔雀鱼和帆鳍鱼（Poecilia）和剑尾鱼（Xiphophorus）有关。花唇鱼是研究性选择（特别是雌性选择）对动物行为和外观影响的重要模式生物。20种Limias在性行为和颜色方面非常多样化，但直到最近才很少被研究。有些种类有精心制作的雄性求偶展示，而其他的则没有;在一些种类中，雄性有五颜六色的鳍和身体标记，而在其他种类中，雄性和雌性都显得很普通。对于为什么物种之间会出现这种差异有一些假设，人们认为行为和颜色可能各自影响另一个的进化。为了评估这些想法，有必要找出不同种类的Limia是如何在遗传学上（或系谱学上）彼此相关的。了解该属的进化史将有助于确定这些特征的进化顺序和方向。研究生亚伦汉密尔顿，在马克·斯普林格博士和大卫·雷兹尼克博士的指导下，正在使用两个基因的DNA测序来评估利米亚属20个物种的关系，一个是核基因，一个是线粒体基因。这些结果可以应用于两个不同的研究领域，性选择理论和地理学。一个比较分析的求偶行为和着色的Limia物种将寻求确定是否有一个显示和阐述男性的颜色模式之间的相关性，显示行为是否是祖先或进化的Limia内，以及是否有任何性状进化超过一次的属。系统发育树也可以与其他加勒比动物的系统发育树进行比较，以寻找共同的地理模式，这可能与加勒比岛屿地质历史的假设相匹配。加勒比群岛一直是生物地理学家争论的焦点，这些岛屿上动物物种的分布主要是受替代事件（如板块构造）或生物体的海外传播的影响。一个强大的系统发育树的20个淡水Limia物种将有助于正在进行的综合知识对这个问题的影响。

0073231Springer and Hamilton Limia is a genus of Caribbean freshwater fishes related to the guppies and sailfin mollies (Poecilia) and swordtails (Xiphophorus). Poeciliid fish are important model organisms for studying the effects of sexual selection (especially female choice) on the behavior and appearance of animals. The 20 species of Limias are very diverse in sexual behaviors and coloration, but have rarely been studied until recently. Some species have elaborate male courtship displays while others do not; in some species males have colorful fin and body markings while in others males and females both appear plain. There are hypotheses for why such differences between species would arise, and it is thought that behavior and coloration may each influence the evolution of the other. To assess these ideas, it is necessary to find out how the different species of Limia are related to each other phylogenetically (or genealogically). Knowing the phylogeny of the genus will help determine the sequence and directionality of evolution of these characteristics. Graduate student Aaron Hamilton, under the direction of Drs. Mark Springer and David Reznick, is evaluating the relationships of the twenty species in the genus Limia using DNA sequencing of two genes, one nuclear and one mitochondrial. The results can then be applied to two different fields of research, sexual selection theory and biogeography. A comparative analysis of the courtship behavior and coloration of Limia species will seek to determine if there is a correlation between the presence of a display and the elaboration of male color patterns, whether display behaviors are ancestral or evolved within Limia, and whether any traits evolved more than once in the genus. The phylogenetic tree can also be compared to those of other Caribbean animals to look for common biogeographic patterns, which may match hypotheses for the geologic history of the Caribbean islands. The Caribbean islands have been a focus of biogeographers debating whether the distribution of animal species on these islands has been influenced primarily by vicariant events (such as plate tectonics) or by over-seas dispersal of the organisms. A robust phylogenetic tree for the 20 freshwater Limia species will contribute to the ongoing synthesis of knowledge bearing on this problem.