Oct. 16 () –
The islands represent just over 5% of the emerged territories, but are home to 31% of the world’s plant species.according to an international study published in Nature in which the Complutense University of Madrid (UCM) participates.
The School of Natural Sciences at Macquarie University (Australia) has led a dozen researchers from Australia, Germany, Spain, the USA, Greece and Japan in analyzing data on more than 304,103 vascular plants, essentially all species known to science throughout the world, discovering the treasure that island biodiversity means.
The team found that 94,052 species are native to islandsof which, 63,280 are endemic—found nowhere else in the world—representing 21% of global plant diversity.
The team’s research provides the first comprehensive assessment of native and endemic vascular plants on marine islands worldwide.
Vascular plants constitute the majority of plants on Earth and include trees, shrubs, herbs, such as grasses, and ferns, and are characterized by having a vascular system with lignin, unlike mosses and liverworts, also called non-vascular plants.
“This is the first time we have such a complete understanding of which species are where, globally. We can now explore the conservation status of some of our rarest plants and “Develop different strategies to conserve them, such as identifying botanical gardens that could house rescue populations.”says Julian Schrader, principal investigator of the work.
The participation of the UCM, providing quality floristic data from Equatorial Guinea and the islands of the Gulf of Guinea, demonstrates how these types of studies are still necessary. Citizen science applications and global diversity repositories do not yet cover 100% of the planet.
“Interestingly, the most diverse, and probably most threatened, areas are still the most unknown.. This work demonstrates how basic work and collaborative efforts produce relevant scientific results,” highlights Francisco J. Cabezas, researcher at the Department of Biodiversity, Ecology and Evolution of the UCM.
The study identified several centers of plant endemism, areas with a high number of species found nowhere else. Almost all are large tropical islands with complex topography and a long history of isolation.
Topping the list is Madagascar, home to a staggering 9,318 species of endemic plants. This African island nation is closely followed by New Guinea (8,793 endemic species), Borneo (5,765), Cuba (2,679) and New Caledonia (2,493).
“Large geographical distances, as well as climates and environments that differ from other archipelagos or continental regions, lead to a high rate of evolution of new species, or ‘speciation’” says Schrader.
Such isolation has given rise to some notable examples of plant evolution. In Hawaii, 126 species of lobelias trace their lineage to a single colonization event, while in the Canary Islands there are groups such as the bejeques (Crassulaceae) in which around fifty species have formed from a single ancestor, a lineage that has subsequently jumped to the rest of the Macaronesian archipelagos, and even to the African continent.
However, many plants that have evolved in isolation, developing unique adaptations to their original ecosystems, may be ill-equipped to compete with introduced species.
The study indicates that climate change “poses an additional threat“, as rising sea levels and the increased frequency of extreme weather events “are potentially devastating for low-lying islands and their unique flora.”
The team has created a standardized checklist of all known vascular plants that occur on islands, documenting their geographic and phylogenetic distribution and conservation risk.
The data set also provides a crucial basis for monitoring changes in island plant communities over time. and could offer a plan to prioritize protection efforts.
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