Ant assemblages have darker and larger members in cold environments
Ant assemblages have darker and larger members in cold environments
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DOI：
10.1111/geb.12516
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发表时间：
2016-12-01
影响因子：
6.4
通讯作者：
Parr, Catherine L.
中科院分区：
文献类型：
--
作者：
Bishop, Tom R.;Robertson, Mark P.;Parr, Catherine L.
在变温动物中，个体角质层的颜色可能具有重要的体温调节和保护作用。在凉爽的环境中，变温动物应该颜色更深，以最大限度地增加热量，而更大，以最大限度地减少热量损失。在高UV-B条件下，深色也应该占主导地位，因为黑色素提供了保护。我们在蚂蚁（膜翅目：蚁科）中测试了这些预测，基于新的、空间和时间上明确的、全球尺度的组合水平和环境数据。地理位置：非洲、澳大利亚和南美洲。方法对三大洲14个海拔样带的274个蚁群进行取样。个别组合的范围为250至3000米a.s.l.（夏季温度为0.5-35摄氏度的最小至最大范围）。我们使用混合效应模型来解释组合角质层亮度的变化。解释变量为平均组合体大小、温度和UV-B辐照。对数据的一个子集检查了亮度的年时间变化。结果体型大的鱼群比体型小的鱼群颜色更深。随着温度的升高，组合物的颜色变浅，但在UV-B含量高的最高温度下，颜色又变暗了。随着时间的推移，温度和体型解释了亮度的变化。空间和时间模型都能解释50%的亮度变化。主要结论本研究结果与热变黑假说一致，说明了在解释昆虫角质层颜色时考虑体型和UV-B辐射的重要性。至关重要的是，这一发现是在组合水平上发现的。因此，蚁群中蚁种的相对丰度和特征会随着海拔、纬度和相对较短时间跨度的环境条件而变化。这些发现表明，对于变温动物组合如何能够对快速变化的环境条件做出反应，存在重要的限制。
AimIn ectotherms, the colour of an individual's cuticle may have important thermoregulatory and protective consequences. In cool environments, ectotherms should be darker, to maximize heat gain, and larger, to minimize heat loss. Dark colours should also predominate under high UV-B conditions because melanin offers protection. We test these predictions in ants (Hymenoptera: Formicidae) across space and through time based on a new, spatially and temporally explicit, global-scale combination of assemblage-level and environmental data.LocationAfrica, Australia and South America.MethodsWe sampled ant assemblages (n=274) along 14 elevational transects on three continents. Individual assemblages ranged from 250 to 3000 m a.s.l. (minimum to maximum range in summer temperature of 0.5-35 degrees C). We used mixed-effects models to explain variation in assemblage cuticle lightness. Explanatory variables were average assemblage body size, temperature and UV-B irradiation. Annual temporal changes in lightness were examined for a subset of the data.ResultsAssemblages with large average body sizes were darker in colour than those with small body sizes. Assemblages became lighter in colour with increasing temperature, but darkened again at the highest temperatures when there were high levels of UV-B. Through time, temperature and body size explained variation in lightness. Both the spatial and temporal models explained c. 50% of the variation in lightness.Main conclusionsOur results are consistent with the thermal melanism hypothesis, and demonstrate the importance of considering body size and UV-B radiation exposure in explaining the colour of insect cuticle. Crucially, this finding is at the assemblage level. Consequently, the relative abundances and identities of ant species that are present in an assemblage can change in accordance with environmental conditions over elevation, latitude and relatively short time spans. These findings suggest that there are important constraints on how ectotherm assemblages may be able to respond to rapidly changing environmental conditions.