Abstract:
Despite the generally negative impact of urbanization on insect biodiversity, some insect species persist in urban habitats. Understanding the mechanisms underpinning the ability of insects to tolerate urban habitats is critical given the contribution of land-use change to the global insect decline. Compensatory mechanisms such as phenotypic plasticity and evolutionary change in thermal physiological traits could allow urban populations to persist under the altered thermal regimes of urban habitats. It is important to understand the contributions of plasticity and evolution to trait change along urbanization gradients as the two mechanisms operate under different constraints and timescales. Here, we examine the plastic and evolutionary responses of heat and cold tolerance (critical thermal maximum [CTmax] and critical thermal minimum [CTmin]) to warming among populations of the cabbage white butterfly, Pieris rapae, from urban and non-urban (rural) habitats using a two-temperature common garden experiment. Although we expected populations experiencing urban warming to exhibit greater CTmax and diminished CTmin through plastic and evolutionary mechanisms, our study revealed evidence only for plasticity in the expected direction of both thermal tolerance traits. We found no evidence of evolutionary divergence in either heat or cold tolerance, despite each trait showing evolutionary potential. Our results suggest that thermal tolerance plasticity contributes to urban persistence in this system. However, as the magnitude of the plastic response was low and comparable to other insect species, other compensatory mechanisms likely further underpin this species\' success in urban habitats.
摘要:
尽管城市化对昆虫生物多样性普遍产生负面影响,一些昆虫物种持续存在于城市栖息地。鉴于土地利用变化对全球昆虫减少的贡献,了解昆虫耐受城市栖息地能力的机制至关重要。诸如表型可塑性和热生理特征的进化变化之类的补偿机制可以使城市人口在城市栖息地的热态变化下持续存在。重要的是要了解可塑性和进化对沿城市化梯度的性状变化的贡献,因为这两种机制在不同的约束和时间尺度下运作。这里,我们研究了卷心菜白蝴蝶种群对增温的热和冷耐受性(临界热最大值[CTmax]和临界热最小值[CTmin])的塑性和进化响应,菜鸟,从城市和非城市(农村)栖息地使用双温度普通花园实验。尽管我们预计经历城市变暖的人群会通过可塑性和进化机制表现出更大的CTmax和减少的CTmin,我们的研究仅揭示了两种耐热性性状在预期方向上的可塑性。我们没有发现耐热性或耐寒性的进化差异的证据,尽管每个性状都显示出进化潜力。我们的结果表明,耐热可塑性有助于该系统中的城市持久性。然而,由于塑料反应的幅度很低,与其他昆虫物种相当,其他补偿机制可能进一步支持该物种在城市栖息地的成功。