Taimyr wolf and the origins of dog
There’s an ongoing debate about where and when dogs originated. The when part might be closer to an answer now. Genetic drift is used by evolutionary biologist to try to recreate the lineage of species. The discovery of a 35,000-year-old wolf rib bone in the Taimyr peninsula in northern Siberia was the key to this story. The DNA from that bone suggests that it diverged from a common ancestor of present-day wolves and dogs near the beginning of the domestic dog lineage. Their technique uses genetic drift of ‘regular’ DNA and mitochondrial DNA.
► Genetic Drift
There are non-lethal random mutations in DNA that survive to the next generation due to natural selection and sometimes due to ‘luck’. Surviving by natural selection makes sense, a mutation affords an advantage so that offspring should excel and survive. Genetic drift is when a mutation doesn’t necessarily result in an advantage but is nevertheless passed on ‘by chance’. Tracing these mutations help create a lineage for evolutionary biologists.
► Mitochondrial DNA vs. Nuclear DNA
Mitochondria are the energy power plants inside cells. They have a few genes necessary for oxidative phosphorylation, which is a fancy term for making energy. The nucleus of the cell is where the chromosomes are. Nuclear DNA is the DNA that you hear about in the news, for example in forensic science. In the figure below, you can see that mitochondrial DNA is passed on only by the mother while nuclear DNA is passed along by both parents. Genetic drift in mitochondrial DNA is much slower and helps refine the lineage of a species. It is slower because it is only inherited by half of the genetic source, i.e., the mother.
You can read a summary of the article in layman’s terms here:
Arctic find confirms ancient origin of dogs
http://news.sciencemag.org/biology/2015/05/arctic-find-confirms-ancient-origin-dogs
Full article and source of the very cool graphical abstract:
Ancient Wolf Genome Reveals an Early Divergence of Domestic Dog Ancestors and Admixture into High-Latitude Breeds
Skoglund et al
Current Biology May 2015
http://www.cell.com/current-biology/abstract/S0960-9822(15)00432-7
Source for the mitochondria DNA figures:
University of California Museum of Paleontology’s Understanding Evolution (http://evolution.berkeley.edu) http://goo.gl/WZgKRV
A bit more reading:
How the wolf became the dog (full article behind paywall)
http://news.sciencemag.org/environment/2015/04/how-wolf-became-dog
Late for #FidoFriday but always on time for #ScienceEveryday
