Department of Biological Sciences, University of Cincinnati, Rieveschl Hall, Cincinnati, OH, 45221, USA.
Section for Animal Ecology, Department of Ecology and Genetics, Evolutionary Biology Centre, Uppsala University, Norbyvägen 18D, 75236, Uppsala, Sweden.
Sci Rep. 2021 Sep 20;11(1):18642. doi: 10.1038/s41598-021-97829-9.
Large-scale latitudinal studies that include both north and south edge populations and address sex differences are needed to understand how selection has shaped trait variation. We quantified the variation of flight-related morphological traits (body size, wing size, ratio between wing size and body size, and wing shape) along the whole latitudinal distribution of the damselfly Lestes sponsa, spanning over 2700 km. We tested predictions of geographic variation in the flight-related traits as a signature of: (1) stronger natural selection to improve dispersal in males and females at edge populations; (2) stronger sexual selection to improve reproduction (fecundity in females and sexual behaviors in males) at edge populations. We found that body size and wing size showed a U-shaped latitudinal pattern, while wing ratio showed the inverse shape. However, wing shape varied very little along the latitudinal gradient. We also detected sex-differences in the latitudinal patterns of variation. We discuss how latitudinal differences in natural and sexual selection regimes can lead to the observed quadratic patterns of variation in body and wing morphology via direct or indirect selection. We also discuss the lack of latitudinal variation in wing shape, possibly due to aerodynamic constraints.
需要进行大规模的南北边缘种群的纬度研究，并解决性别差异问题，以了解选择是如何塑造特征变异的。我们沿着蜻蛉属的整个纬度分布（跨越 2700 公里），量化了与飞行相关的形态特征（体型、翅型、翅型与体型的比例和翅型）的变异。我们检验了飞行相关特征的地理变异预测，作为以下两种假设的特征：（1）在边缘种群中，为了提高雄性和雌性的扩散能力，自然选择更强；（2）在边缘种群中，为了提高繁殖（雌性的繁殖力和雄性的性行为）能力，性选择更强。我们发现，体型和翅型呈现出 U 形的纬度模式，而翅比例则呈现出相反的形状。然而，翅型在纬度梯度上变化很小。我们还检测到了性别差异在变异的纬度模式中的表现。我们讨论了自然选择和性选择制度的纬度差异如何通过直接或间接选择导致身体和翅膀形态的变异呈现二次模式。我们还讨论了翅膀形状缺乏纬度变化的可能原因，这可能是由于空气动力学的限制。
