(ORDO NEWS) — The study, published in the journal Science, provides the clearest picture of the impact of land mammal declines in food webs over the past 130,000 years.
“Although about 6 percent of land mammals have become extinct during this time, we estimate that more than 50 percent of mammals have disappeared from food webs.
And mammals, which are likely to be declining, both in the past and now, are key to the complexity of the mammalian food web,” says environmentalist Evan Frick, lead author of the study.
A food web contains all the links between predators and their prey in a geographic area. Complex food webs are important for regulating populations in a way that allows more species to coexist, maintaining biodiversity and ecosystem stability.
However, animal decline can worsen this complexity by undermining the resilience of ecosystems.
While mammal decline is a well-documented feature of the biodiversity crisis many mammals are now extinct or survive in a small part of their historical geographic range it is unclear how much these losses have worsened the global food web.
To understand what has been lost from the food webs that link land mammals, Frick led a team of scientists from the US, Denmark, the UK and Spain to use the latest machine learning techniques to determine “who ate whom” from 130,000 years ago to the present day.
Frick did the research during a fellowship at Rice University and is currently a research fellow at the Massachusetts Institute of Technology.
Using data from modern observations of predator-prey interactions, Frick and his colleagues trained their machine learning algorithm to recognize how species traits affect the likelihood that one species will prey on another.
Once trained, the model can predict predator-prey interactions between pairs of species that have not been directly observed.
“This approach can tell us who is eating whom today with up to 90% accuracy. This is better than previous approaches could do, and it allowed us to model predator-prey interactions for extinct species,” the scientists say.
Frick says the study provides an unprecedented global look at the food web that linked Ice Age mammals and what food webs would look like today if saber-toothed cats, giant ground sloths, marsupial lions and woolly rhinos still roamed alongside surviving mammals, Frick said. .
An analysis of changes in food webs over time has shown that food webs around the world are being destroyed due to declining animal populations.
“The simulations showed that the food webs of terrestrial mammals have degraded much more than would be expected if a random species went extinct.
Instead of resilience under extinction pressure, these results show a delayed collapse of the food web caused by the selective loss of species central to the food web,” the experts explain.
The study also shows that not all is lost. Although extinctions have caused about half of the recorded reductions in the food web, the rest has been due to the reduction in the geographic ranges of extant species.
“Restoring these species to their historic ranges has great potential to reverse this decline,” says Frick.
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