Evidence of plasticity, but not evolutionary divergence, in the thermal limits of a highly successful urban butterfly

• Published in: Journal of insect physiology Vol. 155; p. 104648
• Main Authors: Lenard, Angie, Diamond, Sarah E.
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.06.2024
• Subjects: Animals; Biological Evolution; Butterflies - physiology; Cold Temperature; Common garden experiment; Critical thermal maximum; Critical thermal minimum; Ecosystem; Lepidoptera; Thermal physiology; Thermotolerance; Urban tolerance; Urbanization; Critical thermal minimum; Urban tolerance; Critical thermal maximum; Thermal physiology; Common garden experiment; Lepidoptera
• ISSN: 0022-1910; 1879-1611; 1879-1611
• DOI: 10.1016/j.jinsphys.2024.104648

[Display omitted] •Urban and rural populations ofP. rapaeboth display beneficial acclimation in heat and cold tolerance traits.•Heat and cold tolerance traits show evolutionary potential that is population-specific and temperature-dependent.•Despite displaying evolutionary potential, tolerance traits have not evolved between rural and urbanP. rapaepopulations. 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.