Berg Florian, Almeland Oda W, Skadal Julie, Slotte Aril, Andersson Leif, Folkvord Arild
University of Bergen, Department of Biology, Bergen, Norway.
Institute of Marine Research (IMR), Nordnes, Bergen, Norway.
PLoS One. 2018 Jan 11;13(1):e0190995. doi: 10.1371/journal.pone.0190995. eCollection 2018.
Atlantic herring, Clupea harengus, have complex population structures. Mixing of populations is known, but the extent of connectivity is still unclear. Phenotypic plasticity results in divergent phenotypes in response to environmental factors. A marked salinity gradient occurs from Atlantic Ocean (salinity 35) into the Baltic Sea (salinity range 2-12). Herring from both habitats display phenotypic and genetic variability. To explore how genetic factors and salinity influence phenotypic traits like growth, number of vertebrae and otolith shape an experimental population consisting of Atlantic purebreds and Atlantic/Baltic F1 hybrids were incubated and co-reared at two different salinities, 16 and 35, for three years. The F1-generation was repeatedly sampled to evaluate temporal variation. A von Bertalanffy growth model indicated that reared Atlantic purebreds had a higher maximum length (26.2 cm) than Atlantic/Baltic hybrids (24.8 cm) at salinity 35, but not at salinity 16 (25.0 and 24.8 cm, respectively). In contrast, Atlantic/Baltic hybrids achieved larger size-at-age than the wild caught Baltic parental group. Mean vertebral counts and otolith aspect ratios were higher for reared Atlantic purebreds than Atlantic/Baltic hybrids, consistent with the differences between parental groups. There were no significant differences in vertebral counts and otolith aspect ratios between herring with the same genotype but raised in different salinities. A Canonical Analysis of Principal Coordinates was applied to analyze the variation in wavelet coefficients that described otolith shape. The first discriminating axis identified the differences between Atlantic purebreds and Atlantic/Baltic hybrids, while the second axis represented salinity differences. Assigning otoliths based on genetic groups (Atlantic purebreds vs. Atlantic/Baltic hybrids) yielded higher classification success (~90%) than based on salinities (16 vs. 35; ~60%). Our results demonstrate that otolith shape and vertebral counts have a significant genetic component and are therefore useful for studies on population dynamics and connectivity.
大西洋鲱（Clupea harengus）具有复杂的种群结构。种群混合现象是已知的，但连通程度仍不明确。表型可塑性导致其在应对环境因素时出现不同的表型。从大西洋（盐度35）到波罗的海（盐度范围为2 - 12）存在明显的盐度梯度。来自这两个栖息地的鲱鱼都表现出表型和遗传变异性。为了探究遗传因素和盐度如何影响生长、椎骨数量和耳石形状等表型特征，将由大西洋纯种和大西洋/波罗的海F1杂种组成的实验种群在16和35这两种不同盐度下孵化并共同饲养三年。对F1代进行多次采样以评估时间变化。冯·贝塔朗菲生长模型表明，在盐度35时，养殖的大西洋纯种的最大体长（26.2厘米）高于大西洋/波罗的海杂种（24.8厘米），但在盐度16时并非如此（分别为25.0厘米和24.8厘米）。相反，大西洋/波罗的海杂种在特定年龄时的体型比野生捕获的波罗的海亲本群体更大。养殖的大西洋纯种的平均椎骨数量和耳石纵横比高于大西洋/波罗的海杂种，这与亲本群体之间的差异一致。具有相同基因型但在不同盐度下饲养的鲱鱼之间，椎骨数量和耳石纵横比没有显著差异。应用主坐标典型分析来分析描述耳石形状的小波系数的变化。第一个判别轴确定了大西洋纯种和大西洋/波罗的海杂种之间的差异，而第二个轴代表盐度差异。基于遗传群体（大西洋纯种与大西洋/波罗的海杂种）对耳石进行分类的成功率（约90%）高于基于盐度（16与35；约60%）。我们的结果表明，耳石形状和椎骨数量具有显著的遗传成分，因此对于种群动态和连通性研究很有用。
