Genetic Structure of Sea Urchin Populations Across a Biogeographic Boundary

摘要本研究的总体研究目的是确定两个温带水海胆同属种：(1)紫海胆（strongylocentrrotus purpuratus）和(2)红海胆（S. franciscanus）自然种群的遗传结构。除了种群遗传调查外，该研究还将在18个月的时间内对几个海胆种群进行三次采样，以确定大小特定的同工酶频率，以评估种群间基因流动的当代水平。本研究旨在填补对海洋无脊椎动物种群结构认识中的两个重要问题：1)跨越边界的物种的遗传结构在多大程度上反映了生物地理边界？2)基因分化的模式是由特定种群间基因流动的障碍、持续的自然选择，还是这些过程的某种组合来最好地解释的？在大多数海洋人口中，对当地人口新兵的来源和移民在人口之间流动的可行性的分析了解甚少。然而，这种理解对于有效管理海洋生物资源是必不可少的。这项研究的数据将用于开展解决上述问题所需的密集种群遗传分析。这样的分析对红海胆来说尤其及时，红海胆目前在加利福尼亚海岸的大部分地区面临着巨大的捕食压力——来自加利福尼亚中部的海獭和其他地区的人类捕鱼活动。圣弗朗西斯卡现在是加州海岸最有价值的无脊椎动物渔场之一。

9415669 Burton PROJECT ABSTRACT The overall research objective of the proposed study is to determine the genetic structure of natural populations of two congeneric species of temperate water sea urchins: (1) the purple urchin, Strongylocentrotus purpuratus, and (2) the red urchin, S. franciscanus. In addition to the population genetic survey, the study will determine size- specific allozyme frequencies in several populations of sea urchins sampled three times over an eighteen month period in order to asses contemporary levels of interpopulation gene flow. The research seeks to fill two important questions in the understanding of the population structure of marine invertebrates: 1) To what extent are biogeographic boundaries reflected in the genetic structure of species which span the boundaries? and 2) Are patterns of genetic differentiation best explained by impediments of gene flow among specific populations, by ongoing natural selection, or by some combination of these processes? Analysis of sources of recruits to local populations and the viability of immigrants moving between populations is poorly understood in most marine populations. Yet such an understanding is essential to the effective management of marine biotic resources. The data from this study will be used to initiate an intensive population genetic analysis required to address the issues mentioned above. Such analyses are especially timely in the case of the red urchin, which currently faces intense predation pressure over much of the California Coast - from sea otters in central California and from human fishing activities in other regions. S. franciscanus now supports one of the most valuable invertebrate fisheries on the California coast.