An international team of scientists, led by Dr. Veronika Laine from the Netherlands Institute of Ecology and Dr. Martien Groenen from Wageningen University, has sequenced and assembled the genome of a well-known songbird, the great tit (Parus major).
The great tit (Parus major). Image credit: Koos Dansen.
Dr. Laine, Dr. Groenen and their colleagues from the United States, Europe, and Japan selected a male great tit from a recent captive population — four generations in captivity — in the Netherlands for genome sequencing and assembly.
To obtain further insight into the evolutionary genetics of this species, they also sequenced the complete genomes an additional 29 wild individuals from across Europe.
“For over 50 years, the great tit has been a model species for research in evolutionary, ecological and behavioral research; in particular, learning and cognition have been intensively studied,” the scientists explained.
“To provide further insight into the molecular mechanisms behind these important traits, we de novo assemble a great tit reference genome and whole-genome re-sequence another 29 individuals from across Europe.”
In addition to looking at the great tit genome, the team investigated the DNA methylation patterns by performing whole-genome sequencing in brain and blood tissue of the reference bird.
“Methylation belongs to the field of epigenetics – the study of what you can inherit not in but ‘on’ your genes,” the scientists explained.
“Specific DNA sequences in the genome can be methylated: methyl groups are added to them, modifying how the genes function.”
“This enabled us to identify regions in the great tit genome that have been under selection during recent evolution of the bird.”
These regions appeared to be overrepresented for genes related to learning and cognition.
“The great tit has evolved to be smart, very smart,” said team member Dr. Kees van Oers, also from the Netherlands Institute of Ecology.
“It’s not your average bird, as it belongs to the top 3% smartest birds when it comes to learning new behavior. That makes it a perfect candidate for research into the evolution of learning, memory and cognitive processes.”
“What research has revealed are so-called conserved patterns of methylation in those same regions, present not only in birds but also in humans and other mammals.”
It’s evidence of a correlation between epigenetic processes such as methylation and the rate of molecular evolution: “the more methylation, the more evolution.”
The findings were published in the Jan. 25 issue of the journal Nature Communications.
“Our study adds to the growing number of representative genomes sequenced across the bird family tree,” the researchers said.
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Laine, V. N. et al. Evolutionary signals of selection on cognition from the great tit genome and methylome. Nat. Commun. 7: 10474; doi: 10.1038/ncomms10474
