Darker ants dominate the canopy: Testing macroecological hypotheses for patterns in colour along a microclimatic gradient.
Darker ants dominate the canopy: Testing macroecological hypotheses for patterns in colour along a microclimatic gradient.
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颜色较深的蚂蚁在树冠上占主导地位：测试宏观生态学假设，以了解沿小气候梯度的颜色模式。
DOI：
10.1111/1365-2656.13110
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发表时间：
2020
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影响因子：
--
通讯作者：
Law SJ
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文献类型：
--
作者：
Law SJ
不同纬度和海拔的外胚层的角质层亮度的梯度已经被证明。三个关键假说被用来解释这些宏观生态模式：热黑化假说(TMH)、黑化-干燥假说(MDH)和光保护假说(PPH)。然而，广泛的非生物测量，如温度、湿度和UV-B辐射，通常用于检测这些生态地理格局，并不能很好地指示蚂蚁等小型曲线型外温动物所经历的微环境。我们测试了这些宏观生态假说是否通过热带雨林中的垂直梯度来解释栖息地和小气候水平上的角质层亮度。我们在低地、热带雨林的四个垂直层次上采样了222种蚂蚁：地下、地下、林下和树冠。我们记录了每个物种的角质层亮度、丰度和估计的身体大小，并计算了每个垂直层的角质层亮度和身体大小的集合加权平均值。记录了每一垂直层的非生物变量(气温、水汽压差和UV-B辐射)，发现蚂蚁群落的角质层亮度是垂直分层的：冠层和林下蚂蚁群落的暗度是地上和地下群落的两倍。角质层的亮度与身体大小无关，也不支持TMH。相反，我们将这种角质层亮度的变化归因于MDH和PPhH的结合。我们的发现表明，在更小的空间尺度上可以检测到广泛的宏观生态格局，而小气候梯度可以塑造特征变化，特别是蚂蚁的角质层亮度。这些结果表明，由于土地利用变化或气候变暖而导致的小气候变化，可能会促使蚂蚁根据角质层的颜色进行选择，从而改变群落结构，并可能改变生态系统的功能。
Gradients in cuticle lightness of ectotherms have been demonstrated across latitudes and elevations. Three key hypotheses have been used to explain these macroecological patterns: the thermal melanism hypothesis (TMH), the melanism‐desiccation hypothesis (MDH) and the photo‐protection hypothesis (PPH). Yet the broad abiotic measures, such as temperature, humidity and UV‐B radiation, typically used to detect these ecogeographical patterns, are a poor indication of the microenvironment experienced by small, cursorial ectotherms like ants.We tested whether these macroecological hypotheses explaining cuticle lightness held at habitat and microclimatic level by using a vertical gradient within a tropical rainforest.We sampled 222 ant species in lowland, tropical rainforest across four vertical strata: subterranean, ground, understory and canopy. We recorded cuticle lightness, abundance and estimated body size for each species and calculated an assemblage‐weighted mean for cuticle lightness and body size for each vertical stratum. Abiotic variables (air temperature, vapour pressure deficit and UV‐B radiation) were recorded for each vertical stratum.We found that cuticle lightness of ant assemblages was vertically stratified: ant assemblages in the canopy and understory were twice as dark as assemblages in ground and subterranean strata. Cuticle lightness was not correlated with body size, and there was no support for the TMH. Rather, we attribute this cline in cuticle lightness to a combination of the MDH and the PPH.Our findings indicate that broad macroecological patterns can be detected at much smaller spatial scales and that microclimatic gradients can shape trait variation, specifically the cuticle lightness of ants. These results suggest that any changes to microclimate that occur due to land‐use change or climate warming could drive selection of ants based on cuticle colour, altering assemblage structure and potentially ecosystem functioning.