New research finds that species with certain characteristics are at higher risk for extinction and perform unique functions within their environments.
(CN) — Species that have a larger risk of extinction also tend to have a bigger impact on the ecosystems in which they live and should be targeted for conservation, according to a study published Friday.
A group of researchers at the University of Tartu in Estonia considered the functions different plants and animals play in predicting what effects their disappearance would have in their Science Advances article.
Looking at over 75,000 different vascular plants, mammals, birds, reptiles and freshwater fish, the study found that species performing certain similar functions were more likely to be threatened with extinction than others.
Species that are large in size and slow to reproduce “are universally threatened,” the researchers said.
“We found that extinction risk is not randomly distributed but localized in certain areas of the functional space occupied by species with large size, slow pace of life, or low fecundity,” the study states.
These traits raised the risk of extinction for plants by three times, birds by six times and mammals by eight. The study also found that the risk for fish and reptiles increased the smaller a species is.
The researchers went further to see how the loss of these “megabiota” species would change global functional diversity.
Each species occupies a “functional space” in its ecosystem, the study found, meaning a plant or animal has specific traits that affect the way it interacts with its environment and with other species living in the same area.
The research group found that while many species have “functional redundancy,” or traits that cluster together in the same functional space “hot spots,” others are more unique.
One plant hot spot includes grasses and herbs. For fish, the hot spot is medium-sized species with generalized functions. Mammals have a major hot spot in species that reproduce quickly and often.
However, some functions in an ecosystem were performed by only a few species. For example, the researchers noted, there are plenty of plants that have the features and functions of grasses, but not many that have those of a redwood tree.
Lead author Carlos P. Carmona said in a statement, “A very interesting result that we found is that, in all these groups, more than half of the species are responsible for less than 20% of the functions performed by the group, therefore implying that 80% of the remaining functions are performed by few species which are functionally unique.”
These unique species could have a large impact on the overall functional organization of an ecosystem if they were to go extinct, while functional redundancy provides a buffer for others.
The data showed that losing threatened species performing key functions made a large impact on the range of functional spaces for mammals, freshwater fish and amphibians in particular.
“Considering the disproportionate importance of the largest species for ecological processes, our results emphasize the importance of actions to prevent the extinction of the megabiota,” the study states. “These results are in line with the notion that larger organisms are more sensitive to global change, a trend affecting plants, land, and aquatic animals that will probably be exacerbated in the future.”
According to the researchers, Earth is experiencing its sixth mass extinction period, triggered by human activity, with almost 1 million species at risk of extinction.
Carmona said the group advises “that species providing unique trait combinations should have a top conservation priority because losing them would imply the complete disappearance of their functions from Earth.”