Scientists are studying how life has recovered from mass extinction in the past in hopes of preventing it for the future.
Past studies have suggested survivors of widespread devastation often "evolve new lifestyles and new anatomical features" in order to save their dying species, a Field Museum press release reported.
Researchers focused on an ancient mammal relative called the anomodont. The population remained "anatomically conservative" despite a mass extinction.
The extinction killed off about 90 percent of marine organisms and 70 percent of land-dwelling creatures.
"Groups of organisms that survive such a mass extinction are said to have passed through an evolutionary bottleneck analogous to the genetic bottleneck that may occur in a population if many of its members die off," Dr. Marcello Ruta of the University of Lincoln, the lead author of the study, said. "At the population level, a genetic bottleneck sometimes allows the population to move to a new evolutionary trajectory, but other times it constrains the future evolution of the population."
Ruta said at the end of the Permian anomodonts exhibited a wide variety of features and body sizes. Variations included "terrestrial plant eaters, amphibious hippo-like species, specialized burrowers, and even tree-dwelling forms."
"The most successful group of anomodonts had canine-like tusks in their upper jaws and turtle-like beaks, and they were the most important terrestrial herbivores of their time," Ruta said.
The variety increased during the Permian, but dropped suddenly at the end of the mass-extinction period.
"The variety of different anatomical features found in anomodonts, i.e. their anatomical diversity (also known as morphological disparity), declined steadily over their history. Even in the aftermath of the mass extinction, when there should have been a lot of empty ecological space, anomodonts did not evolve any fundamentally new features." "This suggests that the evolutionary bottleneck they passed through during the extinction constrained their evolution during the recovery," Professor Jörg Fröbisch, said.
This type of study can help researchers understand how species react to catastrophes.
"This is the first study of its kind to address simultaneously changes in species number and anatomical diversity in anomodonts, and to quantify their response to the most catastrophic extinction on record. Anomodonts are abundant, diverse, and well-studied, which makes them ideal models for evolutionary analyses," Professor Michael Benton said. "The results underscore that recoveries from mass extinctions can be unpredictable, a finding that has important implications for the species extinctions being caused by human activity in the world today. We cannot just assume that life will return to the way it was before the disturbances."
