Human activities could change the pace of evolution, similar to what occurred 66 million years ago when a giant asteroid wiped out the dinosaurs, leaving modern birds as their only descendants. That’s one conclusion drawn by the authors of a new study just published in Systematic Biology.
Dr Daniel Field from the Milner Centre for Evolution at the University of Bath and Cornell PhD candidate Jacob Berv suggest that the meteor-induced mass extinction (a.k.a. the K-Pg event) led to an acceleration in the rate of genetic evolution among its avian survivors. These survivors may have been much smaller than their pre-extinction relatives.
“There is good evidence that size reductions after mass extinctions have occurred in many groups of organisms,” says Berv. Paleontologists have dubbed this phenomenon the “Lilliput Effect”—a nod to the classic tale Gulliver’s Travels. “All of the new evidence we have reviewed is also consistent with a Lilliput Effect affecting birds across the K-Pg mass extinction.”
“Smaller birds tend to have faster metabolic rates and shorter generation times,” Field explains. “Our hypothesis is that these important biological characters, which affect the rate of DNA evolution, may have been influenced by the K-Pg event.”
Rocks and clocks
The researchers jumped into this line of inquiry because of the long-running “rocks and clocks” debate. Different studies often report substantial discrepancies between age estimates for groups of organisms implied by the fossil record and estimates generated by molecular clocks. Molecular…