If “bird brain” ceases to be an insult, at least some of the credit for the change will have to go the great tit (Parus major), a songbird that has long served as a model species in evolutionary, ecological, and behavioral research.
The great tit is now offering researchers genomic and epigenetic insights. That these insights should happen to touch on the evolution of memory, learning, and cognition comes as no surprise to researchers at the Netherlands Institute of Ecology. They note that the great tit is not your average bird. In fact, it ranks in the top 3% of birds when it comes to learning new behavior.
To reveal the molecular mechanisms behind learning and cognition, the researchers de novo assembled a great tit reference genome. They also determined the transcriptome and methylome for a single Dutch specimen. Finally, they conducted whole-genome re-sequencing for another 29 birds from across Europe.
The researchers published their results January 25 in the journal Nature Communications, in an article entitled “Evolutionary signals of selection on cognition from the great tit genome and methylome.”
“We show an overrepresentation of genes related to neuronal functions, learning, and cognition in regions under positive selection, as well as increased CpG methylation in these regions,” wrote the article’s authors. “In addition, great tit neuronal non-CpG methylation patterns are very similar to those observed in mammals, suggesting a universal role in neuronal epigenetic regulation which can affect learning-, memory-, and experience-induced plasticity.”
Essentially, the researchers identified regions in the great tit’s genome that have been under selection during the bird’s recent evolution. These regions appear to be overrepresented for genes related to learning and cognition. In addition, these regions show conserved patterns of methylation—patterns that are also found in humans and other mammals.
These findings suggest a correlation between epigenetic processes such as methylation and the rate of molecular evolution; the more methylation, the more evolution.
“People in our field have been waiting for this for decades,” explained researchers Kees van Oers, Ph.D., and Veronika Laine, ph.D., from the Netherlands Institute of Ecology. The reference genome of their favorite model species, the great tit, is “a powerful toolbox that all ecologists and evolutionary biologists should know about.”
This sentiment was echoed in the conclusion to the article these researchers co-authored. “Our de novo assembled genome will help us to reveal the genetic basis of phenotypic evolution,” the article read. “[This] is essential for understanding how wild species have adapted to our changing planet.”