Limited tolerance by insects to high temperatures across tropical elevational gradients and the implications of global warming for extinction
Limited tolerance by insects to high temperatures across tropical elevational gradients and the implications of global warming for extinction
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DOI：
10.1073/pnas.1507681113
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发表时间：
2016-01-19
影响因子：
11.1
通讯作者：
Kress, W. John
中科院分区：
文献类型：
--
作者：
Garcia-Robledo, Carlos;Kuprewicz, Erin K.;Kress, W. John
临界热最大值 (CTmax)，即动物失去运动控制的温度，有可能决定物种是否能够忍受全球变暖。对于昆虫来说，对高温的耐受力随着纬度的增加而降低，这表明类似的模式也可能沿着海拔梯度存在。这项研究探讨了不同热带食草昆虫（卷叶甲虫）的物种和种群之间 CTmax 在宽和窄海拔梯度上的变化。来自 6,948 次实地观察和 8,700 个博物馆标本的数据被用来绘制哥斯达黎加两座山上卷叶甲虫的海拔分布图。 CTmax 是针对代表梯度上所有种群的 1,252 只甲虫个体确定的。初步形态学鉴定表明，共有 26 个物种，其种群在不同海拔地区表现出不同的温度上限。然而，与形态学鉴定相比，DNA条形码（细胞色素氧化酶I）揭示了显着的隐秘物种多样性。 DNA 条形码识别出 11 个物种复合体中的 42 个物种和单倍型。这 42 个物种的海拔分布和 CTmax 值比 26 个形态定义的物种窄得多。一般来说，在中海拔和山顶发现的物种比低地栖息地的物种对高温的耐受性较差。海拔分布广泛的物种在其分布范围内表现出较高的 CTmax。我们在 CTmax、地理或海拔范围方面没有发现显着的系统发育信号。大多数卷叶甲虫（尤其是高海拔物种）的 CTmax 值差异较小，这表明在某些预计的全球变暖速度下，昆虫灭绝的风险可能很大。
The critical thermal maximum (CTmax), the temperature at which motor control is lost in animals, has the potential to determine if species will tolerate global warming. For insects, tolerance to high temperatures decreases with latitude, suggesting that similar patterns may exist along elevational gradients as well. This study explored how CTmax varies among species and populations of a group of diverse tropical insect herbivores, the rolled-leaf beetles, across both broad and narrow elevational gradients. Data from 6,948 field observations and 8,700 museum specimens were used to map the elevational distributions of rolled-leaf beetles on two mountains in Costa Rica. CTmax was determined for 1,252 individual beetles representing all populations across the gradients. Initial morphological identifications suggested a total of 26 species with populations at different elevations displaying contrasting upper thermal limits. However, compared with morphological identifications, DNA barcodes (cytochrome oxidase I) revealed significant cryptic species diversity. DNA barcodes identified 42 species and haplotypes across 11 species complexes. These 42 species displayed much narrower elevational distributions and values of CTmax than the 26 morphologically defined species. In general, species found at middle elevations and on mountaintops are less tolerant to high temperatures than species restricted to lowland habitats. Species with broad elevational distributions display high CTmax throughout their ranges. We found no significant phylogenetic signal in CTmax, geography, or elevational range. The narrow variance in CTmax values for most rolled-leaf beetles, especially high-elevation species, suggests that the risk of extinction of insects may be substantial under some projected rates of global warming.