An international team of biologists released a report last week warning that when endangered species go extinct, they take down other dependent species with them. The upshot of the finding is that up to 50 percent more species may be endangered than can be currently accounted for by biologists.
“We estimate that 6,300 affiliate species are ‘co-endangered’ with host species currently listed as endangered,” wrote researchers in their report, published in the journal Science. Furthermore, they added that current extinction estimates need to be recalibrated to take co-extinctions into account.
The researchers studied insects, mites, fungi and other organisms uniquely adapted to any of the more than 12,000 threatened or endangered species listed worldwide. “What we found is that with the extinction of a bird, or a mammal or a plant, you aren’t necessarily wiping out just one, single species,” says study researcher Heather Proctor. “We’re also allowing all these unsung dependent species to be wiped out as well.”
Proctor cites the example of a formerly endangered vine in Singapore. When the vine went extinct a few years ago, so did a rare and beautiful species of butterfly that had co-evolved with the plant.
“While co-extinction may not be the most important cause of species extinctions, it is certainly an insidious one,” the report concludes.