Population Structure and Dynamics of the Lemon Shark, Negaprion Brevirostris on a Local and Global Scale: Microsatelite and Mitochondrial DNA Analysis

将进行全面的实地和实验室调查，以确定当地的交配系统和柠檬鲨，Negaprion brevirostris，一个大型的沿海鲨鱼和热带顶端捕食者的地理种群结构。 研究目标是：1）遗传特性，首次，软骨鱼的交配系统; 2）澄清使用的热带苗圃地的幼鲨和女性在paturition;和3）检查人口结构在当地和广泛的地理范围。 在比米尼的研究地点是独一无二的，因为几乎所有的少年人口在泻湖可以和将采样，这些样本的遗传分析将在很大程度上提供数据的前两个目标。具体而言，实地部分包括一个五年抽样方案，其中三年已经完成。 青少年的数据将通过在比米尼及其周围地区采样的成年人的基因分型来补充。 遗传数据和实地数据将共同提供幼仔总人口规模的估计，它们的生长，存活和运动，使用Bimini作为苗圃的雌性数量，以及多年内和跨年的雄性和雌性的相对繁殖成功率。 最后，这些数据可以记录个别雌性是否返回Bimini保育区生产，如果是，雌性的生育间隔和雄性生育后代的数量。 研究的第三个目标是将在比米尼记录的详细的当地遗传结构置于整个物种遗传结构的框架内。将通过在其他四个代表多个空间尺度和潜在扩散障碍的地点对20-30条柠檬鲨进行抽样，实现更大地理尺度的种群结构。 这些地点包括：1）第二个巴哈马地点（大巴哈马岛）从比米尼跨越西北普罗维登斯海峡约100公里; 2）佛罗里达群岛以西的第二个已知柠檬鲨托儿所（Marquesas）与Bimini相隔350 km和佛罗里达海流; 3）远离巴西东海岸的大西洋站点，距离Bimini约5000 km;和4）来自墨西哥太平洋沿岸的样本，通过巴拿马地峡与大西洋站点完全隔离。 本研究将采用微卫星和线粒体DNA两种遗传分析方法。微卫星表现出的变异水平，推断父母/子女和同胞关系在比米尼，特别是当补充由母系遗传的mtDNA提供的额外的遗传信息。 使用非连锁遗传标记具有不同的传输遗传学（mtDNA是母系遗传和微卫星位点表现出孟德尔遗传）将提供单独的，但互补的估计群体内和群体间的遗传变异，提供估计的人口分化和迁移率之间的五个网站在我们的研究，并区分男性和女性介导的基因流模式的推定差异。

Comprehensive field and laboratory investigations will be undertaken to determine the local mating system and geographic population structure of the lemon shark, Negaprion brevirostris, a large coastal shark and a tropical apex predator. The research objectives are to: 1) genetically characterize, for the first time, the mating system of a cartilaginous fish; 2) clarify the use of a tropical nursery ground by juvenile sharks and females in paturition; and 3) examine population structure at both a local and extensive geographic scale. The study site at Bimini is unique in that nearly the entire juvenile population in the lagoon can and will be sampled, and genetic analysis of these samples will in large part provide the data for the first two objectives. Specifically, the field component includes a five-year sampling program of which three years have been completed. The data from juveniles will be supplemented by genotyping adults sampled in and around Bimini. The genetic and field data together will provide estimates of the total population size of pups, their growth, survival and movements, the number of females using Bimini as a nursery ground, and the relative reproductive success of males and females within and across years. Finally, the data can document whether individual females are returning to the Bimini nursery areas to give birth and if so, the interbirth intervals for females and the number of males siring their young. The third objective of the study will allow placement of the detailed local genetic structure documented at Bimini within the framework of the species genetic structure as a whole. Population structure at larger geographic scales will be accomplished through sampling 20-30 lemon sharks at four other locations that represent multiple spatial scales and potential barriers to dispersal. These sites include 1) a second Bahamian site (Grand Bahama Island) approximately 100 km across the NW providence channel from Bimini; 2) a second known lemon shark nursery west of the Florida Keys (Marquesas) separated from Bimini by 350 km and the Florida current; 3) a distant Atlantic site off the east coast of Brazil approximately 5000 km from Bimini; and 4) samples from the Pacific coast of Mexico completely isolated from the Atlantic sites by the Isthmus of Panama. Two methods of genetic analysis, microsatellites and mitochodrial DNA (mtDNA), will be employed in this study. Microsatellites exhibit the levels of variability necessary for inferring parent/offspring and sibship relationships at Bimini, especially when supplemented by additional genetic information provided by the maternally inherited mtDNA. The use of unlinked genetic markers having different transmission genetics (mtDNA is maternally inherited and microsatellite loci exhibit Mendelian inheritance) will provide separate but complementary estimates of genetic variation within and among populations, provide estimates of population differentiation and migration rates between the five sites in our study, and distinguish putative differences in patterns of male and female mediated gene flow.