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The spread of towns and cities is triggering the evolution of plants, reveals a new study. Scientists in Japan have discovered how growing urbanisation is having a major impact on flora as they adapt to urban environments.<\/p>\n
Some species even change the colour of their leaves when they grow in urban areas, reveals the study published in the journal Science Advances.<\/p>\n
The researchers explained that a key characteristic of such environments is the presence of impermeable, heat-retaining surfaces created using brick, stone, asphalt, and concrete. Such surfaces form urban “heat islands” – regions with elevated surface temperatures.<\/p>\n
An unexpected result of heat stress is the impact on the behaviour, physiology, and evolutionary trajectories of resident organisms, according to the findings<\/p>\n
Although previous studies have investigated the role of urban heat stress on evolution in animals, the researchers said its effects on plants remain largely unexplored.<\/p>\n
They investigated how urban heat islands affect the leaf colours of Oxalis corniculata, also known as the creeping woodsorrel. The plant displays diverse leaf colours – ranging from green to red – and is found in both urban and rural areas around the world.<\/p>\n
Research suggests that the colour variations serve as an evolutionary adaptation to protect the plant from environmental stress.<\/p>\n
Moreover, red pigments, called anthocyanins, in the leaves are thought to reduce heat and light-induced damage by intercepting light and forming antioxidants.<\/p>\n
Dr. Yuya Fukano and his team conducted field observations of the leaf colour distribution in the creeping woodsorrel, across urban and rural regions at the local, landscape, and global scales.<\/p>\n
Dr. Fukano said: \u201cWe noticed that the red-leaved variants of the creeping woodsorrel commonly grew near impervious surfaces in urban areas but rarely grew in farmlands or green spaces in and around the city.”<\/p>\n
READ MORE <\/strong> Orchid on remote island ‘pollinated by WASPS – because there are no bees’<\/strong><\/p>\n The team identified a pattern where green-leaved variants of the creeping woodsorrel dominated green spaces while their red-leaf counterparts dominated the urban sites of Tokyo at both the local and landscape levels.<\/p>\n Further examination of an online database showed that the geographical findings were “consistent” across the globe, thereby confirming a link between urbanisation and leaf colour variations in the creeping woodsorrel.<\/p>\n To quantify the adaptive benefits of the leaf colour variations, the research team examined their influence over biomass growth and photosynthetic ability under heat stress and non-heat stress conditions across controlled and uncontrolled cultivation experiments.<\/p>\n The researchers found that the red-leaf variants showed superior growth rates and higher photosynthetic efficiency under high temperatures, whereas green-leaf variants thrived in lower temperatures.<\/p>\n As a result, red-leaf variants tend to thrive in urban areas with low plant density due to high stress tolerance.<\/p>\n\n