Accelerating adaptive trait divergence of annual plants in response to urban habitat diversity in a megacity
The urbanisation process brings about significant changes in natural habitats, with implications for the adaptation of plants to human-dominated environments. Urbanisation leads to habitat loss, fragmentation and changes in abiotic and biotic factors, resulting in reduced diversity and abundance of native plant species. However, it also creates novel selective pressures that drive adaptive evolution in many plant taxa. Traditional approaches to studying urban adaptation have focused primarily on urban-rural comparisons, overlooking the diversity of habitat types within cities. Urban habitats differ in environmental conditions, promoting phenotypic trait divergence in plants, a concept known as the urban divergence hypothesis. Understanding trait evolution in urban environments is complicated by the unclear distinction between local adaptation and neutral evolution, as well as the limited application of reciprocal transplant experiments in urban environments. To address these gaps, our study aims to test the urban divergence hypothesis using Commelina communis, a widely distributed herb in East Asia. Through field surveys, greenhouse experiments and genetic comparisons, we aim to elucidate the mechanisms driving the divergence of adaptive traits in response to urban habitat diversity.