Hamm DE, Burton RS
Marine Biology Research Division, Scripps Institution of Oceanography, University of California, San Diego, 92093-0202, La Jolla, CA, USA
J Exp Mar Biol Ecol. 2000 Nov 20;254(2):235-247. doi: 10.1016/s0022-0981(00)00283-5.
Over the past three decades, the black abalone, Haliotis cracherodii, has experienced precipitous declines in abundance over portions of its range in southern and central California. The potential for recovery of these populations is dependent in part on dispersal processes; that is, can distant populations serve as sources of recruits to locales that no longer harbor H. cracherodii? Here we use population genetic analysis to assess levels of population subdivision and infer recruitment processes. Epipodial tissue samples were obtained from over 400 black abalone from seven geographic sites between Santa Cruz and Santa Barbara counties in central California. Allelic frequencies were determined for each population at three polymorphic enzyme-encoding loci (GPI, AAT-1 and PGM). Significant allelic frequency differentiation among sites was observed at all three loci. Genetic distance was found to be independent of geographic distance over the approximately 300-km sampling range. In addition, a limited number of DNA sequences (total N=51) were obtained for the mitochondrial cytochrome oxidase subunit I gene (COI) from five of the populations. Since the same common COI haplotype dominated each population, this analysis had little statistical power and failed to detect population structure. The observed level of population differentiation at allozyme loci was three-fold higher than that observed in California red abalone, H. rufescens. The species differ in their breeding period and it is suggested that the relatively short, summer breeding season of black abalone limits dispersal because larvae experience reduced variance in oceanographic conditions relative to red abalone that spawn year-round. Based on these results, rates of recolonization and recovery of locally depressed or extirpated black abalone populations are likely to be slow despite harvest restrictions.
在过去三十年中，黑鲍（Haliotis cracherodii）在加利福尼亚州南部和中部的部分分布范围内数量急剧下降。这些种群恢复的潜力部分取决于扩散过程；也就是说，远处的种群能否作为不再有黑鲍栖息地区的补充来源？在这里，我们使用种群遗传分析来评估种群细分水平并推断补充过程。从加利福尼亚州中部圣克鲁斯县和圣巴巴拉县之间七个地理地点的400多只黑鲍中获取了外套膜组织样本。在三个多态性酶编码位点（GPI、AAT-1和PGM）上测定了每个种群的等位基因频率。在所有三个位点上均观察到各地点之间显著的等位基因频率差异。在大约300公里的采样范围内，发现遗传距离与地理距离无关。此外，从五个种群中获得了线粒体细胞色素氧化酶亚基I基因（COI）的有限数量的DNA序列（总数N = 51）。由于相同的常见COI单倍型在每个种群中占主导地位，该分析的统计效力很小，未能检测到种群结构。在等位酶位点观察到的种群分化水平比加利福尼亚红鲍（H. rufescens）中观察到的水平高三倍。这两个物种的繁殖期不同，有人认为黑鲍相对较短的夏季繁殖季节限制了扩散，因为相对于全年产卵的红鲍，黑鲍的幼虫在海洋学条件下的差异较小。基于这些结果，尽管有捕捞限制，但当地数量减少或灭绝的黑鲍种群的重新定殖和恢复速度可能会很慢。
