The evolutionary history of flowering plants are threatened with extinction

Climate change is not only pushing species to the brink of extinction, it is erasing a vast proportion of the ‘evolutionary history’ of the world’s flowering plants’ — or how these organisms relate to one another on the tree of life, which changes over time.

No less than a fifth (21 %) of the world’s understudied angiosperms’ (flowering plants) evolutionary history is at risk of extinction, nearly double that of jawed vertebrates (13%), according to a first wildlife assessment of its kind by researchers from the Royal Botanic Gardens, Kew, Zoological Society of London and their international collaborators, published in Science. 

Evolutionarily distinct and globally endangered species are found primarily in the world’s tropics, such as Madagascar (950 species), Borneo (561 species), and Ecuador. Scientists identified 9,945 “priority species” that are evolutionarily distinct and globally endangered.

For instance, the vibrant maidenhair tree, Ginkgo biloba, is the sole known descendant of an ancient lineage dating back more than 300 million years in East Asia. Afrothismia gesnerioides (Burmanniaceae) is a nonphotosynthetic mycoheterotrophic herb (which relies on fungi rather than photosynthesis for its nutrition) from the Nyangong forest in Cameroon. Another endangered angiosperm species, Hondurodendron urceolatum is a dioecious tree (with distinct male and female individuals) scattered across a single mountain range in the Parque Nacional El Cusuco, Honduras.

“Angiosperms comprise 1445 billion years (Gyr) of evolutionary history… of which more than one-fifth is threatened,” they found. In angiosperms, the proportion of threatened evolutionary history is higher than in most vertebrate clades, although within vertebrates, “it is comparable to crocodilians (21%),” said the paper.

Species that are the only representatives of ancient lineages contain a distinct evolutionary history, explained the paper, adding that “the conservation of evolutionary history is closely associated with the preservation of feature diversity (i.e., the variety of species’ traits).” This is inextricably linked with current and future benefits for society and nature that the floral diversity can provide, it said.

The authors studied phylogenetic information (the study of evolutionary relationships among organisms) and concluded that global biodiversity policies must recognise “the necessity to preserve [floral] evolutionary lineages, as their diversity underpins current and future benefits to people and the future of life on Earth.”

Biodiversity conservation should go beyond “species to preserve” and maximise the preservation of the “tree of life,” the authors added. With more than two in five plants estimated to be at risk of extinction… “now is the time to catalyze a new generation of conservation monitoring and action for the many distinct, overlooked, and threatened plant species on Earth.”

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