Urban conditions are driving adaptive radiation in a plant species, with significant differences in traits like height and flowering period across habitats such as farmland, parks, and roadside environments within the Keihanshin region.

Adaptation appears linked to urban factors—higher ground temperatures from the heat island effect, artificial shading, and lower soil acidity—collectively contributing to trait diversification, including an observed rise in maximum ground temperature by about 8°C in cities.

Researchers conducted field comparisons across diverse urban habitats in Osaka, Kyoto, and Kobe to understand how urban habitat diversity shapes evolution.

The work is published in the Journal of Ecology in 2025 and was funded by the Japan Science and Technology Agency and the Japan Society for the Promotion of Science, with collaboration from the University of Hyogo.

Funding and collaboration details note support from JST and JSPS, collaboration with the University of Hyogo, and the study being summarized in EurekAlert!

Prominent researchers cited include Kobe University ecologist Ushimaru Atushi and former graduate student Nakata Taichi, now at Kyushu University.

Future work will include cultivation experiments that simulate field conditions to test trait benefits and investigate the extent to which adaptations are embedded in the plants’ DNA.

Follow-up studies will use controlled yet field-like conditions to assess fitness advantages of different traits and determine genetic encoding of these adaptations.

In summary, researchers aim to clarify how cultivation under realistic conditions reveals the benefits of divergent traits and their possible genomic engravement.

This study serves as a starting point for broader research into how urban habitat diversity in megacities shapes plant evolution.

Source: Adaptive trait divergence of annual plants in response to urban habitat diversity in a megacity, Journal of Ecology, 2025 (DOI: 10.1111/1365-2745.70193).

The research provides evidence of rapid adaptive evolution—occurring in roughly six decades due to urbanization—ruling out founder effects as the sole cause and highlighting urban environments as a driver of adaptive diversification.

The trait differences emerged within about 60 years, indicating rapid adaptive evolution rather than drift from founding populations.