Dieker Petra, Beckmann Luisa, Teckentrup Julia, Schielzeth Holger
Department of Evolutionary Biology Bielefeld University Bielefeld Germany.
Department of Population Ecology Institute of Ecology and Evolution Friedrich Schiller University Jena Jena Germany.
Ecol Evol. 2018 Jun 27;8(15):7273-7284. doi: 10.1002/ece3.4156. eCollection 2018 Aug.
Discrete color polymorphisms represent a fascinating aspect of intraspecific diversity. Color morph ratios often vary clinally, but in some cases, there are no marked clines and mixes of different morphs occur at appreciable frequencies in most populations. This poses the questions of how polymorphisms are maintained. We here study the spatial and temporal distribution of a very conspicuous color polymorphism in the club-legged grasshopper . The species occurs in a green and a nongreen (predominately brown) morph, a green-brown polymorphism that is common among Orthopteran insects. We sampled color morph ratios at 42 sites across the alpine range of the species and related color morph ratios to local habitat parameters and climatic conditions. Green morphs occurred in both sexes, and their morph ratios were highly correlated among sites, suggesting shared control of the polymorphism in females and males. We found that in at least 40 of 42 sites green and brown morphs co-occurred with proportions of green ranging from 0% to 70% with significant spatial heterogeneity. The proportion of green individuals tended to increase with decreasing summer and winter precipitations. Nongreen individuals can be further distinguished into brown and pied individuals, and again, this polymorphism is shared with other grasshopper species. We found pied individuals at all sites with proportions ranging from 3% to 75%, with slight, but significant variation between years. Pied morphs show a clinal increase in frequency from east to west and decreased with altitude and lower temperatures and were more common on grazed sites. The results suggest that both small-scale and large-scale spatial heterogeneity affects color morph ratios. The almost universal co-occurrence of all three color morphs argues against strong effects of genetic drift. Instead, the data suggest that small-scale migration-selection balance and/or local balancing selection maintain populations polymorphic.
离散颜色多态性是种内多样性的一个迷人方面。颜色形态比例通常呈渐变群变化，但在某些情况下，没有明显的渐变群，不同形态的混合在大多数种群中以可观的频率出现。这就提出了多态性如何维持的问题。我们在此研究棒足蝗中一种非常显著的颜色多态性的时空分布。该物种存在绿色和非绿色（主要为棕色）两种形态，这种绿棕多态性在直翅目昆虫中很常见。我们在该物种高山分布范围内的42个地点对颜色形态比例进行了采样，并将颜色形态比例与当地栖息地参数和气候条件相关联。绿色形态在两性中都有出现，且其形态比例在各地点间高度相关，这表明雌性和雄性的多态性受到共同控制。我们发现，在42个地点中的至少40个，绿色和棕色形态共存，绿色形态的比例从0%到70%不等，存在显著的空间异质性。绿色个体的比例往往随着夏季和冬季降水量的减少而增加。非绿色个体可进一步分为棕色和杂色个体，同样，这种多态性也存在于其他蝗虫物种中。我们在所有地点都发现了杂色个体，其比例从3%到75%不等，年份间有轻微但显著的差异。杂色形态的频率从东到西呈渐变增加，随海拔和温度降低而减少，在放牧地更为常见。结果表明，小尺度和大尺度的空间异质性都会影响颜色形态比例。所有三种颜色形态几乎普遍共存，这与遗传漂变的强烈影响相悖。相反，数据表明小尺度的迁移 - 选择平衡和/或局部平衡选择使种群保持多态性。
