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Synopsis Cities, through the generation of urban heat islands, provide a venue for exploring contemporary convergent evolution to climatic warming. We quantified how repeatable the evolution of heat tolerance, cold tolerance, and body size was among diverse lineages in response to urban heat islands. Our study revealed significant shifts toward higher heat tolerance and diminished cold tolerance among urban populations. We further found that the magnitude of trait divergence was significantly and positively associated with the magnitude of the urban heat island, suggesting that temperature played a major role in the observed divergence in thermal tolerance. Despite these trends, the magnitude of trait responses lagged behind environmental warming. Heat tolerance responses exhibited a deficit of 0.84°C for every 1°C increase in warming, suggesting limits on adaptive evolution and consequent adaptational lags. Other moderators were predictive of greater divergence in heat tolerance, including lower baseline tolerance and greater divergence in body size. Although terrestrial species did not exhibit systematic shifts toward larger or smaller body size, aquatic species exhibited significant shifts toward smaller body size in urban habitats. Our study demonstrates how cities can be used to address long-standing questions in evolutionary biology regarding the repeatability of evolution. Importantly, this work also shows how cities can be used as forecasting tools by quantifying adaptational lags and by developing trait-based associations with responses to contemporary warming.
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Invasive Spotted Lanternflies ( Lycorma delicatula ) Are Larger in More Urban Areas
Synopsis Urbanization promotes the formation of heat islands. For ectothermic animals in cities, the urban heat island effect can increase developmental rate and result in smaller adult body size (i.e., the temperature-size rule). A smaller adult body size could be consequential for invasive urban ectotherms due to potential effects of body size on thermal tolerance, dispersal distance, and fecundity. Here, we explored the effect of urbanization on body size in the spotted lanternfly (Lycorma delicatula), an invasive planthopper (Hemiptera: Fulgoridae) that is rapidly spreading across urban and non-urban settings in the United States. We then evaluated the consequences of spotted lanternfly body size for heat tolerance, a trait with importance for ectotherm survival in urban heat islands. Contrary to our expectations, we found that both male (P = 0.011) and female (P < 0.001) spotted lanternflies were larger in more urbanized areas and that females displayed a positive effect of body size on resistance to hot temperatures (P = 0.018). These results reject plasticity in developmental rate due to the urban heat island effect as an explanation for spotted lanternfly body size and instead lend necessary (but insufficient) support to an adaptive explanation stemming from advantages of larger body size in cities. This study demonstrates a positive effect of urbanization on spotted lanternfly body size, with potential implications for dispersal distance, fecundity, and thermal tolerance in urban areas.
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- Award ID(s):
- 2312129
- PAR ID:
- 10636910
- Publisher / Repository:
- Oxford University Press
- Date Published:
- Journal Name:
- Integrative And Comparative Biology
- Volume:
- 65
- Issue:
- 2
- ISSN:
- 1540-7063
- Format(s):
- Medium: X Size: p. 276-284
- Size(s):
- p. 276-284
- Sponsoring Org:
- National Science Foundation
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