One study shows that large, long-lived, low-fertility living things at risk of extinction, whether plant or animal, are responsible for 80% of the functional diversity in the planet’s ecosystems. The work is published in the journal Science Advances by an international consortium with the participation of the Desertification Research Centre (CIDE, UV-CSIC-GVA).
The accelerated rate of species extinction could endanger the health of ecosystems around the planet. This could be due, among other causes, to the impact of the extinction of certain species whose role is key in maintaining the functions and services that ecosystems provide. This is the main conclusion of a study published in the prestigious journal Science Advances by an international consortium involving Francesco de Bello, a researcher at the Centre for Research on Desertification (CIDE), a joint centre of the Spanish National Research Council (CSIC), the University of Valencia (UV) and the Valencian Government (GVA). That is why they have analysed the functions of 75,000 species, plants and animals, of the more than one million considered endangered, calculating their importance in the functioning of terrestrial ecosystems.
The work is led by University of Tartu (Estonia) researcher Carlos Carmona, of whom Francesco de Bello was the former supervisor, and shows that the extinction of species considered endangered by the International Union for Conservation of Nature (IUCN) would significantly change, and on a global scale, the range of functions performed by plants, mammals, birds, amphibians, reptiles and freshwater fish in ecosystems.
From shrews and water lentils to blue whales and redwoods, animals and plants exhibit extraordinary variability in their functional and morphological characteristics, including wide differences in size, weight, shape, or reproductive capacity. These characteristics determine the role that species play in ecosystems, and also how they respond to the different impacts of global change.
The balance of ecosystems therefore depends not only on the number and variety of species that make them up and their relationships, but also on the role that different species play in maintaining this balance. This functional diversity means considering that not all species have the same role and that different species can be involved in the different processes that take place in ecosystems, and can play different or similar roles.
Thus, some particular functions performed by a taxonomic group such as plants, mammals or freshwater fish, may be redundant among many species or only supported by a few. If these functions are highly redundant, extinction of part of the species is unlikely to strongly affect the functions of the entire group. On the contrary, if certain functions are performed by one or a few species, their disappearance will lead to a reduction in the overall range of functions.
One million of endangered species
In the current context of global decline in biodiversity, with one million species estimated to be endangered, it is important to determine to what extent these extinctions will alter the functional characteristics of plants and animals. Through the analysis of the phylogenetic information and of various functional traits (morphological, physiological and phenological characteristics) of more than 75,000 species, the global functional spectrum of each of the groups studied has been characterised.
“We used information on functional traits of 39,260 species of vascular plants, 4,953 mammals, 9,802 birds, 6,567 reptiles, 6,776 amphibians and 10,705 freshwater fish from different published databases. For each of these groups, we choose a set of fundamental functional traits associated with different key aspects of their ecology”, explains CIDE researcher Francesco de Bello.
According to this work, more than half of the species are responsible for less than 20% of the functions performed by these groups, which implies that 80% of the remaining functions are performed by a few species, with unique functional characteristics, of which there are not many other functionally redundant species. Over the next century, if the extinctions fit the IUCN predictions, the functional decline would be between 0.3% (for reptiles) and 5.1% (for freshwater fish). Although this decline is still limited, it would be accompanied by a significant increase in the range of functions that a single species would support (from 17% to 23% depending on the group), increasing the impact of future extinctions.
More vulnerable to future extinctions
Given that the risk of extinction is not randomly distributed, but it is the species with the largest sizes, great longevity and late sexual maturity that are much more likely to be threatened, “their extinction would cause notable reorganisations in the functional spectra of the majority groups, making them more vulnerable to future extinctions in the future”, concludes Carlos Carmona, main researcher. “If extinctions occur faster than expected, there will be a marked increase in global functional decline, which seems likely given the current acceleration of changes on a planetary scale”, warns the researcher from the University of Tartu. In this sense, this type of research can be of great interest for biodiversity management and conservation policies.
Carlos P. Carmona, Riin Tamme, Meelis Pärtel, Francesco de Bello, Sébastien Brosse, Pol Capdevila, Roy González-M., Manuela González-Suárez, Roberto Salguero-Gómez, Maribel Vásquez-Valderrama, Aurèle Toussaint (2021). Erosion of global functional diversity across the tree of life. Science Advances.