Data from: Lateral plate number in low-plated threespine stickleback: a study of plasticity and heritability

In the threespine stickleback Gasterosteus aculeatus model system, phenotypes are often classified into three morphs according to lateral plate number. Morph identity has been shown to be largely genetically determined, but substantial within-morph variation in plate number exists. In this study, we test whether plate number has a plastic component in response to salinity in the low-plated morph using a split-clutch experiment where families were split in two, one half raised in water at 0 and the other at 30 ppt salt. We find a small salinity-induced plastic effect on plate number in an unexpected direction, opposite to what we predicted: Fish raised in freshwater on average have slightly more plates than fish raised in saltwater. Our results confirm that heritability of plate number is high. Additionally, we find that variance in plate number at the family level can be predicted from other family level traits, which might indicate that epistatic interactions play a role in creating the observed pattern of lateral plate number variation.在三棘刺鱼（Gasterosteus aculeatus）模式系统中，研究者通常根据侧骨板数量将其表型划分为三种形态型。已有研究证实，形态型特征主要由遗传因素决定，但同一形态型内的骨板数量仍存在显著变异。本研究以低骨板形态型的三棘刺鱼为对象，采用分窝实验设计：将每个家系分为两组，分别置于盐度0 ppt与30 ppt的水环境中饲养，以此探究骨板数量是否存在响应盐度的可塑性组分。本研究发现，盐度诱导的骨板数量可塑性效应虽小，但方向与预期完全相反：淡水饲养的刺鱼平均骨板数量略高于海水饲养个体。本研究结果证实骨板数量的遗传力较高。此外，我们发现家系水平的骨板数量方差可通过其他家系水平性状进行预测，这提示上位性互作可能在塑造侧骨板数量变异的观测模式中发挥作用。