Variation in flower size and shape of Impatiens capensis is correlated with urbanization in Montreal, Canada

• Published in: Ecology and evolution Vol. 13; no. 12; pp. e10826 - n/a
• Main Authors: Faure, Julie, Volz, Valentine, Joly, Simon
• Format: Journal Article
• Language: English
• Published: England John Wiley & Sons, Inc 01.12.2023; John Wiley and Sons Inc; Wiley
• Subjects: Abiotic factors; Animals; Botany; Bumblebees; Cities; Environmental impact; Evolutionary Ecology; flower shape and size; Flowers; Flowers & plants; geometric morphometrics; Habitat fragmentation; Habitats; Herbivory; Impatiens capensis; Morphometry; Organisms; Phenology; Plant nectar; Plant reproduction; Plants (botany); Pollination; pollinator visitation rates; Pollinators; Soil properties; Soil temperature; Soil water; Urban Ecology; Urbanization; Variation; Vegetation; Vegetation index; Water availability; Canada; Montreal Quebec Canada; flower shape and size; pollinator visitation rates; urbanization; geometric morphometrics
• ISSN: 2045-7758; 2045-7758
• DOI: 10.1002/ece3.10826

Urbanization is changing the conditions in which many species live, forcing them to adjust to these novel environments. Floral size and shape are critical traits for the reproduction of plants pollinated by animals as they are involved in the attraction of pollinators and in efficient pollination. Variation in size and shape could be affected by urbanization via its modification of the abiotic environment (habitat fragmentation, water availability, temperature, soil properties), or via its impact on the biotic environment of plants (pollination, herbivory). Although numerous studies have assessed the impact of urbanization on pollinator communities and many plant traits, few have investigated its impact on floral size and shape while quantifying the proportion of the total urbanization effect that is due to biotic interactions. In this study, we tested if urbanization and pollinator visitation rates affect the flower shape of the spotted jewelweed, Impatiens capensis. We quantified the size and shape of flowers in frontal and profile views using geometric morphometrics for 228 individuals from six populations from the region of Montreal, Canada. Pollinator visitation rates were estimated at each site and the main pollinators were found to be bumblebees, honeybees and hummingbirds. We found that floral size and shape are significantly correlated with urbanization as measured by the amount of vegetation in the surrounding environment of the plants (mean normalized vegetation index, NDVI) and by the visitation rates of bumblebees and honey bees. Partitioning of the total flower shape variation suggests that urbanization affects flower shape through abiotic factors and via its impact on pollinator visitation rates. While further studies from other cities are necessary to confirm the role of urbanization in shaping the floral shape of I. capensis, these results support the idea that urbanization could affect flower shapes. We found that the flower shape and size of the jewelweed is correlated with urbanization. Urban populations tend to have smaller flowers and sepals with shorter spurs. These changes are partly explained by vegetation cover and by variations in pollinator communities.