Data from: Insect temperature-body size trends common to laboratory, latitudinal and seasonal gradients are not found across altitudes

1. Body size affects rates of most biological and ecological processes, from individual performance to ecosystem function, and is fundamentally linked to organism fitness. Within species, size at maturity can vary systematically with environmental temperature in the laboratory and across seasons, as well as over latitudinal gradients. Recent meta-analyses have revealed a close match in the magnitude and direction of these size gradients in various arthropod orders, suggesting that these size responses share common drivers.
2. As with increasing latitude, temperature also decreases with increasing altitude. Although the general direction of body size clines along altitudinal gradients has been examined previously, to our knowledge altitude-body size (A-S) clines have never been synthesised quantitatively, nor compared with temperature-size (T-S) responses measured under controlled laboratory conditions.
3. Here we quantitatively examine variation in intraspecific A-S clines among 121 insect species from 50 different global locations, representing 12 taxonomic orders. While some taxa were better represented in the literature than others, our analysis reveals extensive variation in the magnitude and direction of A-S clines. Following the assumption that temperature on average declines by 1°C per 150m increase in altitude, order-specific A-S clines in the field appear to deviate from laboratory T-S responses. Specifically, the magnitude of A-S clines and T-S responses are more closely matched in some taxonomic orders (e.g. Diptera) than others (e.g. Orthoptera). These findings contrast with the strong co-variation observed between latitude-size clines and T-S responses, and between laboratory and seasonal T-S responses.
4. The lack of clear size relationships with elevation, and hence temperature, is likely due to the counteracting effects of other major drivers with altitude, including season length and oxygen partial pressure. Switches in voltinism within species across altitude, and the dispersal of individuals across different elevations, may also obscure trends.

1. 体型是绝大多数生物与生态过程速率的核心调控因子，其影响范围覆盖个体表现直至生态系统功能，且与生物体的适合度存在本质关联。在物种内部，成熟个体体型会随环境温度呈现系统性变化——无论是实验室环境、野外季节波动，还是沿纬度梯度的分布格局均是如此。近期的元分析（meta-analyses）显示，多个节肢动物（arthropod）类群的体型渐变群在幅度与方向上均高度吻合，表明这类体型响应机制存在共同的驱动因素。
2. 与纬度升高类似，气温也会随海拔升高而降低。此前虽已有研究探讨了沿海拔梯度的体型渐变群的总体趋势，但据我们所知，目前尚未有研究对种内（intraspecific）海拔-体型（altitude-body size, A-S）渐变群进行定量综合分析，也未将其与受控实验室条件下测得的温度-体型（temperature-size, T-S）响应进行对比。
3. 本研究针对来自全球50个采样点、隶属于12个分类学目共计121种昆虫的种内海拔-体型渐变群变异展开定量分析。尽管部分类群在已有文献中的记录量多于其他类群，但我们的分析结果显示，海拔-体型渐变群的幅度与方向存在广泛变异。基于“海拔每升高150米，平均气温下降1℃”的假设，野外观测到的目级尺度海拔-体型渐变群与实验室条件下的温度-体型响应并不一致。具体而言，部分类群（如双翅目Diptera）的海拔-体型渐变群幅度与温度-体型响应的匹配度要高于其他类群（如直翅目Orthoptera）。这一发现与此前观测到的纬度-体型渐变群与温度-体型响应、实验室与季节型温度-体型响应之间的强共变关系形成鲜明对比。
4. 目前尚未观测到体型与海拔（进而与温度）间存在明确的关联，这一现象可能源于其他随海拔变化的主要驱动因子的抵消作用，比如生长季长度与氧分压（oxygen partial pressure）。此外，物种沿海拔梯度的世代数（voltinism）变化，以及不同海拔间个体的扩散行为，也可能掩盖了潜在的体型渐变趋势。