Private Bag 129, Institute for Marine and Antarctic Studies, University of Tasmania, Hobart, Tasmania 7001, Australia.
Mol Ecol. 2011 Aug;20(16):3439-54. doi: 10.1111/j.1365-294X.2011.05173.x. Epub 2011 Jul 6.
Recent molecular research on Antarctic benthic organisms has challenged traditional taxonomic classifications, suggesting that our current perceptions of Antarctic biodiversity and species distributions must be thoroughly revised. Furthermore, genetic differentiation at the intraspecific level remains poorly understood, particularly in eastern Antarctica. We addressed these issues using DNA sequence data for two sibling amphipod species that could be collected on a circum-Antarctic scale: Eusirus perdentatus and Eusirus giganteus. Haplotype networks and Bayesian phylogenies based on mitochondrial (COI, CytB) and nuclear (ITS2) DNA provided strong evidence of multiple cryptic species of Eusirus, with several occurring in sympatry and at least one likely to have a true circum-Antarctic distribution. Within species, gene flow was often highly restricted, consistent with a brooding life history and in some cases suggestive of current or future allopatric speciation. Patterns of genetic structure were not always predictable: one cryptic species showed preliminary evidence of high genetic differentiation across ∼150 km in eastern Antarctica (F(ST) > 0.47, P < 0.01), yet another was remarkably homogenous across ∼5000 km (F(ST) = 0.00, P = 1.00). Genetic diversity also varied among cryptic species, independent of sample size (π = 0.00-0.99). These results indicate several hidden levels of genetic complexity in these Antarctic amphipods that are neither apparent from previous taxonomic or ecological studies nor predictable from their life history. Such genetic diversity and structure may reflect different modes of survival for Antarctic benthic organisms during historic glacial cycles, and/or subsequent re-establishment of populations on the shelf, and highlight our misunderstanding of Antarctic marine species diversity.
最近对南极底栖生物的分子研究挑战了传统的分类学分类，这表明我们目前对南极生物多样性和物种分布的认识必须彻底修订。此外，种内水平的遗传分化仍然知之甚少，特别是在东南极洲。我们使用可以在环南极范围内收集的两种有亲缘关系的片脚类动物（Eusirus perdentatus 和 Eusirus giganteus）的 DNA 序列数据来解决这些问题：Eusirus 有多个隐种，线粒体（COI、CytB）和核（ITS2）DNA 的单倍型网络和贝叶斯系统发育为这些隐种提供了强有力的证据，其中一些在同域共存，至少有一种可能具有真正的环南极分布。在种内，基因流通常受到高度限制，这与亲代抚育的生活史一致，在某些情况下表明存在当前或未来的异域物种形成。遗传结构模式并不总是可预测的：一个隐种在东南极洲约 150 公里的范围内表现出初步的高遗传分化证据（F(ST) > 0.47，P < 0.01），而另一个种在约 5000 公里的范围内却非常同质（F(ST) = 0.00，P = 1.00）。遗传多样性也因隐种而异，与样本量无关（π = 0.00-0.99）。这些结果表明，这些南极片脚类动物存在几种隐藏的遗传复杂性，这些复杂性既不是从以前的分类学或生态学研究中明显的，也不是从它们的生活史中可预测的。这种遗传多样性和结构可能反映了南极底栖生物在历史冰川周期中的不同生存模式，以及/或随后在大陆架上重新建立种群，并突出了我们对南极海洋物种多样性的误解。
