Moth body size increases with elevation along a complete tropical elevational gradient for two hyperdiverse clades
Moth body size increases with elevation along a complete tropical elevational gradient for two hyperdiverse clades
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DOI：
10.1111/ecog.03917
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发表时间：
2019-04-01
期刊：
影响因子：
5.9
通讯作者：
Colwell, Robert K.
中科院分区：
文献类型：
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作者：
Brehm, Gunnar;Zeuss, Dirk;Colwell, Robert K.
动物的体型大小可能是其最重要的功能特征。对于节肢动物来说，体型变化的环境驱动因素仍然缺乏记录和了解，特别是在热带地区。我们使用沿着哥斯达黎加广泛的热带海拔梯度收集的两个物种丰富、系统发育独立的蛾类群（鳞翅目：尺蛾科；牛蒡子亚科）的独特数据集，来研究体型变化的相关性和可能的原因。我们研究了 15 047 件尺蛾科标本（794 种）和 4167 件牛蒡子科标本（308 种），以检验以下假设：1）体型随着环境温度的降低而增加，正如温度-体型规则所预测的那样； 2) 体型随着降雨量和初级生产力的增加而增加，正如从抗饥饿性考虑中预测的那样； 3）随着高度的增加，机身尺寸与机翼面积异速缩放，使得机翼载荷（机身尺寸与机翼面积的比率）随着高度的增加而减小，以补偿较低的空气密度。为了检验这些假设，我们检查了前翅长度作为身体大小的代理与环境温度、降雨量、植被指数和海拔的关系，作为线性和多项式空间回归模型的解释变量。我们使用两种主要方法分别分析了雄性和雌性的数据：每个地点物种的平均前翅长度，以及完整的当地组合的平均前翅长度，按丰度加权。在两个类群、两种途径、两种性别以及物种内，体型都随着海拔的升高而持续增加。温度是这种模式的最佳预测因子（-0.98 < r < -0.74），而体型与降雨量和增强植被指数不相关或弱相关。机翼载荷随高度增加而增加。我们的结果支持温度-体型规则是节肢动物沿热带海拔梯度体型变化的重要机制，而抗饥饿性和飞行力学的优化似乎不太重要。
The body size of an animal is probably its most important functional trait. For arthropods, environmental drivers of body size variation are still poorly documented and understood, especially in tropical regions. We use a unique dataset for two species-rich, phylogenetically independent moth taxa (Lepidoptera: Geometridae; Arctiinae), collected along an extensive tropical elevational gradient in Costa Rica, to investigate the correlates and possible causes of body-size variation. We studied 15 047 specimens (794 species) of Geometridae and 4167 specimens (308 species) of Arctiinae to test the following hypotheses: 1) body size increases with decreasing ambient temperature, as predicted by the temperature-size rule; 2) body size increases with increasing rainfall and primary productivity, as predicted from considerations of starvation resistance; and 3) body size scales allometrically with wing area, as elevation increases, such that wing loading (the ratio of body size to wing area) decreases with increasing elevation to compensate for lower air density. To test these hypotheses, we examined forewing length as a proxy for body size in relation to ambient temperature, rainfall, vegetation index and elevation as explanatory variables in linear and polynomial spatial regression models. We analysed our data separately for males and females using two principal approaches: mean forewing length of species at each site, and mean forewing length of complete local assemblages, weighted by abundance. Body size consistently increased with elevation in both taxa, both approaches, both sexes, and also within species. Temperature was the best predictor for this pattern (-0.98 < r < -0.74), whereas body size was uncorrelated or weakly correlated with rainfall and enhanced vegetation index. Wing loading increased with elevation. Our results support the temperature-size rule as an important mechanism for body size variation in arthropods along tropical elevational gradients, whereas starvation resistance and optimization of flight mechanics seem to be of minor importance.