Population genetic analysis of a recent range expansion: mechanisms regulating the poleward range limit in the volcano barnacle Tetraclita rubescens
Population genetic analysis of a recent range expansion: mechanisms regulating the poleward range limit in the volcano barnacle Tetraclita rubescens
复制标题
DOI：
10.1111/j.1365-294x.2010.04588.x
复制
发表时间：
2010-04-01
影响因子：
4.9
通讯作者：
Sanford, Eric
中科院分区：
文献类型：
--
作者：
Dawson, Michael N.;Grosberg, Richard K.;Sanford, Eric
随着与气候变化同时发生的范围变化的记录越来越多，描述范围边界原因的努力也随之增加。三种机制——遗传贫困、迁移负荷或扩散的物理障碍——在理论上得到了很好的描述，但区分它们所需的数据却很少收集。我们描述了冬青藤壶 (Tetraclita rubescens) 的分布、丰度、遗传变异和环境，这是一种潮间带藤壶，自 20 世纪 70 年代以来，其北部范围范围从美国加利福尼亚州旧金山扩大了数百公里。我们将丰度的地理变化与非生物和生物模式进行比较，包括海面温度和 387 个共生物种的分布，并描述了细胞色素 C 氧化酶亚基 I、线粒体非编码区和来自巴伊亚马格达莱纳（加利福尼亚州下加利福尼亚州，墨西哥）和门多西诺角（美国加利福尼亚州）之间 27 个地点的 9 个微卫星位点的遗传变异。我们发现非常高的基因流、高遗传多样性以及与范围限制一致的物理环境变化梯度。我们推断，冬凌草北部范围边界的主要原因是不适应的等位基因流入外围位置所产生的迁移负荷，而环境变化可能减少了对迁移到该范围新殖民部分的基因型的选择，是观察到的范围扩张的最可能原因。由于环境变化可能同样影响一个区域中的所有类群，其分布限制是由迁移负荷确定的，因此这些机制可能是范围边界和很大程度上同步的多物种范围扩张的常见原因。
As range shifts coincident with climate change have become increasingly well documented, efforts to describe the causes of range boundaries have increased. Three mechanisms-genetic impoverishment, migration load, or a physical barrier to dispersal-are well described theoretically, but the data needed to distinguish among them have rarely been collected. We describe the distribution, abundance, genetic variation, and environment of Tetraclita rubescens, an intertidal barnacle that expanded its northern range limit by several hundreds of kilometres from San Francisco, CA, USA, since the 1970s. We compare geographic variation in abundance with abiotic and biotic patterns, including sea surface temperatures and the distributions of 387 co-occurring species, and describe genetic variation in cytochrome c oxidase subunit I, mitochondrial noncoding region, and nine microsatellite loci from 27 locations between Bahia Magdalena (California Baja Sur, Mexico) and Cape Mendocino (CA, USA). We find very high gene flow, high genetic diversity, and a gradient in physical environmental variation coincident with the range limit. We infer that the primary cause of the northern range boundary in T. rubescens is migration load arising from flow of maladapted alleles into peripheral locations and that environmental change, which could have reduced selection against genotypes immigrating into the newly colonized portion of the range, is the most likely cause of the observed range expansion. Because environmental change could similarly affect all taxa in a region whose distributional limits are established by migration load, these mechanisms may be common causes of range boundaries and largely synchronous multi-species range expansions.