Cities are often hotter and drier compared with nearby undeveloped areas, but how organisms respond to these multifarious stressors associated with urban heat islands is largely unknown. Terrestrial isopods are especially susceptible to temperature and aridity stress as they have retained highly permeable gills from their aquatic ancestors. We performed a two temperature common garden experiment with urban and rural populations of the terrestrial isopod, Oniscus asellus, to uncover evidence for plastic and evolutionary responses to urban heat islands. We focused on physiological tolerance traits including tolerance of heat, cold, and desiccation. We also examined body size responses to urban heat islands, as size can modulate physiological tolerances. We found that different mechanisms underlie responses to urban heat islands. While evidence suggests urban isopods may have evolved higher heat tolerance, urban and rural isopods had statistically indistinguishable cold and desiccation tolerances. In both populations, plasticity to warmer rearing temperature diminished cold tolerance. Although field‐collected urban and rural isopods were the same size, rearing temperature positively affected body size. Finally, larger size improved desiccation tolerance, which itself was influenced by rearing temperature. Our study demonstrates how multifarious changes associated with urban heat islands will not necessarily contribute to contemporary evolution in each of the corresponding physiological traits.

中文翻译：

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证据表明，国际化的陆地等足类动物为了应对更热、更干燥的城市条件，进化出了耐热性，但没有进化出耐干燥性


与附近的未开发地区相比，城市通常更热、更干燥，但生物体如何应对与城市热岛相关的多种压力源在很大程度上尚不清楚。陆生等足类动物特别容易受到温度和干旱胁迫的影响，因为它们保留了水生祖先的高度渗透性的鳃。我们对陆地等脚类动物Oniscus asellus的城市和农村种群进行了两种温度的普通花园实验，以发现城市热岛的可塑性和进化反应的证据。我们关注生理耐受性特征，包括耐热、耐寒和干燥。我们还研究了体型对城市热岛的反应，因为体型可以调节生理耐受性。我们发现城市热岛反应有不同的机制。虽然有证据表明城市等足类动物可能进化出了更高的耐热性，但城市和农村等足类动物在统计上没有区分寒冷和干燥的耐受性。在这两个种群中，对较高饲养温度的可塑性降低了耐寒性。尽管野外收集的城市和乡村等足类动物体型相同，但饲养温度对体型有积极影响。最后，较大的尺寸提高了耐干燥性，这本身受到饲养温度的影响。我们的研究表明，与城市热岛相关的多种多样的变化并不一定会促进当代各个相应生理特征的进化。