A new study reveals that Asteraceae, the botanical family that includes daisies and sunflowers, forms the most diverse group of plants on dozens of islands worldwide. The humble daisies may turn out to be a gold mine for understanding why and how new species evolve in the world’s most isolated environments - that is, if we manage to study them before they go extinct.
The most diverseplant family
The research team, among which Naturalis researchers Luis Valente and Lizzie Roeble, has created a comprehensive global database of island Asteraceae species, revealing that it is the most diverse plant family on oceanic islands. The family consists of around 34,000 species with a wide global distribution. They include familiar names such as artichoke, chamomile, dahlia, and lettuce, daisies, and sunflowers. It was a surprise that more isolated islands tend to host higher numbers of unique species. With over 6,000 species analyzed, nearly 60% are found only on islands.
The treasure chestof tropic islands
Asteraceae have undergone rapid evolutionary changes on islands, resulting in species that often differ significantly from their mainland relatives. This evolutionary process is known as species radiation. Radiations often lead to striking differences in size, shape, and habitat preferences among the new species.
From the modest stickseeds (Bidens) of the Pacific Islands, to the alien-looking and highly endangered silverswords of Hawai’i, to the giant daisy trees (Scalesia) of the Galápagos. Although species radiations are more famously documented in animals, such as Darwin’s finches in the Galápagos, this research indicates that Asteraceae may host a record number of radiations on islands worldwide. Many of these radiations are yet to be formally discovered, mostly located on tropical islands such as the Caribbean, Madagascar, and New Guinea.
A surprising countof radiations
Lizzie Roeble
“Botanists had long suspected that the daisy family had evolved in remarkable ways on islands, but our study reveals that the extent of evolutionary innovation in this family may be much greater than previously imagined."
Global hotspotfor evolution
This discovery opens up new possibilities for understanding the mechanisms driving plant diversification. Many of these species, however, are critically endangered, with only a few individuals surviving in remote and often inaccessible island habitats. Given their restricted distributions and unique evolutionary history, the protection of these species is crucial. Island ecosystems harbor not only incredible diversity but also highly specialized species.
Island conservationis urgent
The study reminds us of the vulnerable biodiversity on islands. Many of these species are found in highly localized, inaccessible areas and face threats from habitat loss, climate change, and human activities. The daisy family has an incredible evolutionary potential. Their conservation is essential in preventing these unique species from disappearing forever.
