Beringian sub-refugia revealed in blackfish (Dallia): implications for understanding the effects of Pleistocene glaciations on Beringian taxa and other Arctic aquatic fauna.
Beringian sub-refugia revealed in blackfish (Dallia): implications for understanding the effects of Pleistocene glaciations on Beringian taxa and other Arctic aquatic fauna.
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DOI：
10.1186/s12862-015-0413-2
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发表时间：
2015-07-19
影响因子：
3.4
通讯作者：
López JA
中科院分区：
文献类型：
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作者：
Campbell MA;Takebayashi N;López JA
更新世气候的不稳定性对北极生物的分布和丰度产生了深远而多样的影响，这一点可以从现存北极种群中记录的生物地理格局的变化中得到揭示。为了更好地了解地理和古气候对白令海淡水鱼的影响，我们研究了属Dallia（黑鱼：Esociformes：Esocidae）的遗传变异。白令海鱼属（Dallia）包括一至三种小型、耐寒和耐缺氧的淡水鱼，分布范围仅限于从费尔班克斯附近的育空地区河流域向西包括阿拉斯加西部的Kuskokwim河流域和低洼地区，到楚科奇半岛北侧的Amguema河和楚科奇半岛南侧的Mechigmen湾。该属有一个不连续的分布由白令海峡和布鲁克斯范围划分。我们研究了在这一范围内的遗传变异的分布，以确定潜在的子避难所内的大白令岛避难所的数量和位置，以及白令陆桥，布鲁克斯范围内的作用，和大的河流白令岛内塑造目前的分布的Dallia的人口。我们的分析是基于DNA序列数据从两个核基因内含子（S7和RAG 1）和两个线粒体基因组片段从十九个采样点。这些数据进行了研究，根据遗传聚类和合并的框架，以确定子避难所内的更大的Beringia避难所，并推断不同人群的Dallia的人口历史。我们确定了多达五个不同的Dallia基因簇。这些基因簇中有四个存在于阿拉斯加：（1）在布鲁克斯山脉北部发现的北极沿海平原遗传簇，（2）位于Kuskokwim和育空地区河流域上游位置的阿拉斯加内陆遗传簇，（3）在苏厄德半岛发现的遗传簇，以及（4）阿拉斯加沿海遗传集群，包括Kuskokwim河下游和育空地区河流域样本位置，以及来自阿拉斯加西南部的样本，这些排水管。楚科奇样品被分配到自己的遗传聚类（5），类似于阿拉斯加沿海的遗传聚类。在主成分判别分析（DAPC）和结构中实施的聚类和排序分析显示，大多数一致的分组和组间的高度分化。被确定为遗传簇的采样地点组对应于由可能的地理障碍划分的地理区域，包括布鲁克斯山脉和白令海峡。在白令海附近的育空地区河和Kuskokwim河流域，序列多样性（θ）估计值最高。我们还推断遗传簇之间的不对称迁移率。在阿拉斯加的北极沿海平原上的Dallia的隔离与阿拉斯加沿海遗传集群和北极沿海平原遗传集群之间的极低估计迁移率相关。我们的研究结果支持一个方案，多个水生子避难所在白令海在更新世和保存现存的人口Dallia的结构。通过白令陆桥推断出的Dallia的历史存在解释了西白令尼亚和阿拉斯加西部沿海Dallia遗传组成的相似性。相比之下，布鲁克斯山脉在历史上和当代的孤立形成了今天北极沿海平原Dallia的独特性。总的来说，这项研究发现了高度的遗传结构之间的人群Dallia支持多个白令亚避难所的想法在更新世，这似乎是保持到现在，由于严格的淡水性质和低扩散能力的属。本文的在线版本（doi：10.1186/s12862-015-0413-2）包含补充材料，可供授权用户使用。
Pleistocene climatic instability had profound and diverse effects on the distribution and abundance of Arctic organisms revealed by variation in phylogeographic patterns documented in extant Arctic populations. To better understand the effects of geography and paleoclimate on Beringian freshwater fishes, we examined genetic variability in the genus Dallia (blackfish: Esociformes: Esocidae). The genus Dallia groups between one and three nominal species of small, cold- and hypoxia-tolerant freshwater fishes restricted entirely in distribution to Beringia from the Yukon River basin near Fairbanks, Alaska westward including the Kuskokwim River basin and low-lying areas of Western Alaska to the Amguema River on the north side of the Chukotka Peninsula and Mechigmen Bay on the south side of the Chukotka Peninsula. The genus has a non-continuous distribution divided by the Bering Strait and the Brooks Range. We examined the distribution of genetic variation across this range to determine the number and location of potential sub-refugia within the greater Beringian refugium as well as the roles of the Bering land bridge, Brooks Range, and large rivers within Beringia in shaping the current distribution of populations of Dallia. Our analyses were based on DNA sequence data from two nuclear gene introns (S7 and RAG1) and two mitochondrial genome fragments from nineteen sampling locations. These data were examined under genetic clustering and coalescent frameworks to identify sub-refugia within the greater Beringia refugium and to infer the demographic history of different populations of Dallia. We identified up to five distinct genetic clusters of Dallia. Four of these genetic clusters are present in Alaska: (1) Arctic Coastal Plain genetic cluster found north of the Brooks Range, (2) interior Alaska genetic cluster placed in upstream locations in the Kuskokwim and Yukon river basins, (3) a genetic cluster found on the Seward Peninsula, and (4) a coastal Alaska genetic cluster encompassing downstream Kuskokwim River and Yukon River basin sample locations and samples from Southwest Alaska not in either of these drainages. The Chukotka samples are assigned to their own genetic cluster (5) similar to the coastal Alaska genetic cluster. The clustering and ordination analyses implemented in Discriminant Analysis of Principal Components (DAPC) and STRUCTURE showed mostly concordant groupings and a high degree of differentiation among groups. The groups of sampling locations identified as genetic clusters correspond to geographic areas divided by likely biogeographic barriers including the Brooks Range and the Bering Strait. Estimates of sequence diversity (θ) are highest in the Yukon River and Kuskokwim River drainages near the Bering Sea. We also infer asymmetric migration rates between genetic clusters. The isolation of Dallia on the Arctic Coastal Plain of Alaska is associated with very low estimated migration rates between the coastal Alaska genetic cluster and the Arctic Coastal Plain genetic cluster. Our results support a scenario with multiple aquatic sub-refugia in Beringia during the Pleistocene and the preservation of that structure in extant populations of Dallia. An inferred historical presence of Dallia across the Bering land bridge explains the similarities in the genetic composition of Dallia in West Beringia and western coastal Alaska. In contrast, historic and contemporary isolation across the Brooks Range shaped the distinctiveness of present day Arctic Coastal Plain Dallia. Overall this study uncovered a high degree of genetic structuring among populations of Dallia supporting the idea of multiple Beringian sub-refugia during the Pleistocene and which appears to be maintained to the present due to the strictly freshwater nature and low dispersal ability of this genus. The online version of this article (doi:10.1186/s12862-015-0413-2) contains supplementary material, which is available to authorized users.