Natural hybridization between Calanus finmarchicus and C. glacialis (Copepoda) in the Arctic and Northwest Atlantic
Natural hybridization between Calanus finmarchicus and C. glacialis (Copepoda) in the Arctic and Northwest Atlantic
复制标题
北极和西北大西洋的 Calanus finmarchicus 和 C. glacialis (Copepoda) 的自然杂交
DOI：
10.4319/lo.2012.57.4.1057
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发表时间：
2012
影响因子：
4.5
通讯作者：
J. Turgeon
中科院分区：
文献类型：
--
作者：
G. Parent;S. Plourde;J. Turgeon
Calanus glacialis 和 Calanus finmarchicus 分别在北极和北大西洋的浮游动物群落中占主导地位。这些物种之间巨大的同源区、繁殖季节重叠的可能性以及判别性状中间值的证据表明这些物种存在杂交。我们使用 1 个线粒体 (16S) 和 10 个核位点（微卫星）对来自 14 个北极到大西洋站点的 684 个人进行了基因分型。亲本物种之间强烈的遗传差异可以自信地识别出同源地区的杂种。混合频率在各站之间变化很大，并且与年平均海面温度不一致。在圣劳伦斯河口，亲本和杂交基因型在不同的采样日期和深度层（300-100 m 和 100-0 m）之间非随机分布，且杂交在 7 月似乎比 5 月和 9 月更为频繁。总体而言，亲本和杂种基因型的双峰频率分布表明生殖障碍限制了这些物种之间的基因流动。杂交的机会更可能受到物种繁殖物候差异的限制，而不是扩散的限制。杂交还会影响前体长度，这是一种广泛用于区分哲水蚤物种的形态特征，因此可能导致物种错误识别。高度渗入的个体表明杂交种具有繁殖力和繁殖力，这表明杂交适应性可能会影响这些物种种群动态的估计和模型。这是海洋浮游动物物种之间种间杂交的第一个证据，但使用核遗传标记可以在密切相关且形态相似的海洋浮游动物物种群体中发现类似的情况。
Calanus glacialis and Calanus finmarchicus dominate the zooplankton community in the Arctic and North Atlantic, respectively. The vast zone of sympatry between these species, the potential for overlap between reproductive seasons, and the evidence for intermediate values of discriminant traits suggest that these species hybridize. We genotyped 684 individuals from 14 Arctic to Atlantic stations using one mitochondrial (16S) and 10 nuclear loci (microsatellites). Strong genetic differentiation between parental species confidently identified hybrids in areas of sympatry. Hybrid frequency was highly variable among stations and did not covary with mean annual sea surface temperature. In the St. Lawrence Estuary, parental and hybrid genotypes were nonrandomly distributed between depth layers (300–100 m and 100–0 m) and across sampling dates, and hybrids seemed more frequent in July than in May and September. Overall, the bimodal frequency distribution of parental and hybrid genotypes suggests that reproductive barriers limit gene flow between these species. The opportunity for interbreeding is more likely restricted by differences in species reproductive phenology than by dispersal. Hybridization also affects prosome length, a morphological trait widely used to discriminate Calanus species, and thus possibly contributes to species misidentification. Highly introgressed individuals indicate that hybrids are fertile and reproduce, suggesting that hybrid fitness could affect estimates and models of these species population dynamics. This is the first evidence for interspecific hybridization between marine zooplankton species, but similar cases could be uncovered using nuclear genetic markers in groups of closely related and morphologically similar marine zooplankton species.