Chicken study reveals speedy and dynamic evolution

Mutations in chicken genomes suggest that evolution rates could occur 15 times faster than previously thought. Scientists led by Oxford University’s Research Laboratory for Archaeology studied individual chickens that were part of a pedigree and found two mutations had occurred in the mitochondrial genomes in only 50 years.

“Our study shows that evolution can move much faster in the short term than we had believed from fossil-based estimates,” said research leader Professor Greger Larson.

Previous studies had suggested that the rate of change in the mitochondrial genome was never faster than about 2% per million years. The team used a well-documented 50 year pedigree population of chicken and reconstructed the mitochondrial DNA passed from mothers to daughters within the population of 12 chickens of the same generation.The results, published online in Biology Letters, showed more than a 10-fold difference in the size of the chickens when weighed at 56 days old.

“Our observations reveal that evolution is always moving quickly but we tend not to see it because we typically measure it over longer time periods. Our study shows that evolution can move much faster in the short term than we had believed from fossil-based estimates. Previously, estimates put the rate of change in a mitochondrial genome at about 2% per million years. At this pace, we should not have been able to spot a single mutation in just 50 years, but in fact we spotted two,” said senior author Professor Larson.

The team also discovered a single instance of mitochondrial DNA being passed down from a father. “We identified chicks who inherited their mitochondria from their father, meaning so-called “paternal leakage” can happen in avian populations. Both of these findings demonstrate the speed and dynamism of evolution when observed over short time periods,” said research associate Dr Michelle Alexander.

Paper: http://rsbl.royalsocietypublishing.org/content/11/10/20150561