Collaborative Research: QTL Analysis of a Cave Fish

0216103/0217178 Browsky Tabin这项研究的长期目标是了解发育遗传差异的本质，这些差异使一个物种的所有个体都是独特的，并将不同的物种彼此区分开来。 为此，将研究两种密切相关但遗传上不同的鱼类之间的差异。 墨西哥四，Astyanax mexicanus，有一些人口生活在河流和其他人生活在洞穴中。 洞穴形式与它们的表面亲属不同，眼睛和色素沉着大大减少。 它们生活的洞穴提供的食物很少，它们已经通过发展较慢的新陈代谢来适应这一点。 其他感官过度发达，以弥补视觉的缺乏：例如，嗅觉、味觉以及检测振动和电流的能力。 它们不仅能在永恒的黑暗中生存，还能在洞穴中茁壮成长。利用微卫星DNA标记，将在洞穴和地表形式之间的杂交中，以精细的比例绘制这种物种的基因组。 杂交种的图谱和进一步分析将允许检测和表征负责洞穴和表面形式之间差异的基因（QTL）。 研究结果将对性状差异的“遗传结构”进行估计：涉及的基因数量和它们各自影响的大小，以及它们在基因组中相对于彼此的位置。 一些主要效应QTL的位置信息将用于鉴定和克隆基因，这将有助于其功能分析。 这些结果将揭示涉及复杂性状的发育和维持的遗传途径，如脊椎动物的眼睛和感觉系统的其他方面，色素沉着，行为和代谢的控制。 研究结果还将揭示区分种群和物种的遗传差异的性质，以及性状相关性对进化变化的限制。

0216103/0217178Browsky Tabin The long term goal of this research is to understand the nature of the developmental genetic differences that make all individuals of a species unique, and distinguish the various species from one another. Towards this end, differences between two types of fishes that are closely related, but genetically distinct, will be studied. The Mexican tetra, Astyanax mexicanus, has some populations that live in rivers and others that live in caves. Cave forms differ from their surface relatives by having greatly reduced eyes and pigmentation. The caves in which they live provide little food and they have adapted to this by developing a slower metabolism. Other senses are overdeveloped to compensate for the lack of vision: e.g., smell, taste and the ability to detect vibration and current. Not only can they survive eternal darkness, they thrive in caves.The genome of this species will be mapped at a fine scale using microsatellite DNA markers, in hybrids between the cave and surface forms. The map and further analysis of the hybrids will permit the detection and characterization of genes (QTL) that are responsible for the differences between cave and surface forms. The results will give estimates of the "genetic architecture" of trait differences: the number of genes involved and magnitudes of their individual effects, and their positions in the genome relative to one another. Positional information of some of the major effect QTL will be used to identify and clone the genes; this will facilitate their functional analysis. The results will shed light on the genetic pathways involved in development and maintenance of complex traits, like the vertebrate eye and other aspects of the sensory system, control of pigmentation, behavior and metabolism. The results will also inform on the nature of genetic differences distinguishing populations and species, and on the constraints on evolutionary change resulting from trait correlations.