Wing morphological responses to latitude and colonisation in a range expanding butterfly.
Wing morphological responses to latitude and colonisation in a range expanding butterfly.
复制标题
翼对纬度和定殖的形态反应在扩大蝴蝶的范围内。
作者：
Taylor-Cox ED;Macgregor CJ;Corthine A;Hill JK;Hodgson JA;Saccheri IJ
人口经历快速的气候驱动的范围扩张的经验，不同的选择制度占主导地位的增加分散在前沿和陡峭的环境梯度。与这种扩张相关的性状的表征提供了对选择压力和进化约束的深入了解，这些压力和约束塑造了人口和进化反应。在这里，我们调查模式的三个组成部分的翅膀形态（大小，形状，颜色）往往与分散能力和温度调节，沿着纬度梯度的范围扩展的斑点木蝴蝶（Pararge aegeria）在英国（两个地区的扩展在英格兰和苏格兰）。我们测量了来自54个地点的774名男性，跨越799公里，10年平均温度梯度为4 °C。一个几何形态测量方法被用来调查前翅和后翅的大小和形状的变化;颜色，图案和翅膀的对比度进行了检查，使用的亮度（黑度的倒数）的措施。总的来说，机翼的尺寸随着纬度的增加而增加，每100公里增加0.2%，与伯格曼的规则一致。前翅变得更圆，后翅更拉长的殖民历史，可能反映了增加扩散能力的选择。相反的热黑化的预期，翅膀的颜色是较轻的幼虫在较冷的温度和无关的长期温度。翅斑模式的变化也被检测到。高异质性研究的所有特征的网站之间的方差可能反映了进化的时间滞后和遗传漂变，由于殖民新的栖息地。我们的研究表明，温度敏感的塑料反应的大小和颜色与选择的传播特性（翅膀的大小和形状）。虽然在某些情况下，可塑性和进化反应可能会相互对抗，但P. aegeria的快速扩张意味着这两种机制之间的整体增强效应。
Populations undergoing rapid climate-driven range expansion experience distinct selection regimes dominated both by increased dispersal at the leading edges and steep environmental gradients. Characterisation of traits associated with such expansions provides insight into the selection pressures and evolutionary constraints that shape demographic and evolutionary responses. Here we investigate patterns in three components of wing morphology (size, shape, colour) often linked to dispersal ability and thermoregulation, along latitudinal gradients of range expansion in the Speckled Wood butterfly (Pararge aegeria) in Britain (two regions of expansion in England and Scotland). We measured 774 males from 54 sites spanning 799 km with a 10-year mean average temperature gradient of 4 °C. A geometric morphometric method was used to investigate variation in size and shape of forewings and hindwings; colour, pattern, and contrast of the wings were examined using a measure of lightness (inverse degree of melanism). Overall, wing size increased with latitude by ∼2% per 100 km, consistent with Bergmann’s rule. Forewings became more rounded and hindwings more elongated with history of colonisation, possibly reflecting selection for increased dispersal ability. Contrary to thermal melanism expectations, wing colour was lighter where larvae developed at cooler temperatures and unrelated to long-term temperature. Changes in wing spot pattern were also detected. High heterogeneity in variance among sites for all of the traits studied may reflect evolutionary time-lags and genetic drift due to colonisation of new habitats. Our study suggests that temperature-sensitive plastic responses for size and colour interact with selection for dispersal traits (wing size and shape). Whilst the plastic and evolutionary responses may in some cases act antagonistically, the rapid expansion of P. aegeria implies an overall reinforcing effect between these two mechanisms.