Ocean barriers and glaciation: evidence for explosive radiation of mitochondrial lineages in the Antarctic sea slug Doris kerguelenensis (Mollusca, Nudibranchia)
Ocean barriers and glaciation: evidence for explosive radiation of mitochondrial lineages in the Antarctic sea slug Doris kerguelenensis (Mollusca, Nudibranchia)
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DOI：
10.1111/j.1365-294x.2008.04071.x
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发表时间：
2009-03
影响因子：
4.9
通讯作者：
N. Wilson;M. Schrödl;K. Halanych
中科院分区：
文献类型：
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作者：
N. Wilson;M. Schrödl;K. Halanych
强劲的水流和深水通道可能成为大陆海洋动物幼体扩散的障碍，但对直接发育者的潜在影响尚未得到充分研究。我们检查了 Doris kerguelenensis 的遗传结构，Doris kerguelenensis 是一种直接发育的海蛞蝓，出现在德雷克海峡（将南极洲与南美洲分隔开的水体）上。我们发现德雷克海峡两岸的种群内存在深刻的线粒体分歧，南美动物与南极动物形成了多个姐妹群关系。广义分子钟表明，这些跨德雷克对在上新世-更新世期间，德雷克海峡形成后发生了分歧。统计简约方法恢复了 29 个独立的单倍型网络（许多是同域的），这些网络可能与重复的冰川周期引起的异域事件相关。 16S 的数据一致，但比 COI 更保守，并且估计的祖先 16S 单倍型广泛存在。这两个线粒体基因之间的替代率的显着差异导致了对连接性的不同估计。对网络的人口统计分析揭示了一些选择和扩大人口的证据。与北半球相比，南极洲的冰川作用似乎增加了而不是减少了遗传多样性。这表明基于北半球系统发育地理学的轨道强迫范围动力学并不适用于南极洲。在 D. kerguelenensis 中发现的不同谱系表明最近存在爆炸性辐射，这可能反映了冰川事件期间的多个避难所，以及随后有限的扩散。无论是否被认为是隐秘物种，南极海洋无脊椎动物的遗传多样性似乎高于形态分析的预期，并支持南极生物多样性泵现象。
Strong currents and deep passages of water can be barriers for larval dispersal of continental marine animals, but potential effects on direct developers are under‐investigated. We examined the genetic structure of Doris kerguelenensis, a directly developing sea slug that occurs across the Drake Passage, the body of water separating Antarctica from South America. We found deep mitochondrial divergences within populations on both sides of the Drake Passage, and South American animals formed multiple sister‐group relationships with Antarctic animals. A generalised molecular clock suggested these trans‐Drake pairs diverged during the Pliocene–Pleistocene, after the formation of the Drake Passage. Statistical parsimony methods recovered 29 separate haplotype networks (many sympatric) that likely correlate with allopatric events caused by repeated glacial cycles. Data from 16S were congruent but more conserved than COI, and the estimated ancestral 16S haplotype was widespread. The marked difference in the substitution rates between these two mitochondrial genes results in different estimates of connectivity. Demographic analyses on networks revealed some evidence for selection and expanding populations. Contrasting with the Northern Hemisphere, glaciation in Antarctica appears to have increased rather than reduced genetic diversity. This suggests orbitally forced range dynamics based on Northern Hemisphere phylogeography do not hold for Antarctica. The diverse lineages found in D. kerguelenensis point towards a recent, explosive radiation, likely reflecting multiple refuges during glaciation events, combined with limited subsequent dispersal. Whether recognised as cryptic species or not, genetic diversity in Antarctic marine invertebrates appears higher than expected from morphological analyses, and supports the Antarctic biodiversity pump phenomenon.