Tiny bird, tiny genome

Scientists have determined that hummingbirds have the least amount of DNA compared to all other birds, reptiles, or mammals.   This reduced DNA is evident in all species of hummingbirds, indicating that the DNA was pared down before speciation.  Scientists have also identified a link between small amounts of DNA and higher metabolic rates.  It is believed that smaller genomes allow for smaller cells and a resulting larger surface-to-volume cell ratio.  This link is evident not only in hummingbirds, but also in most other birds and bats.



This study is being conducted by Ryan Gregory and his colleagues at the University of Guelph in Canada.  By staining DNA in the nucleus and analyzing it’s density, they have estimated the genome size of 37 species of hummingbirds.   Scientists believe hummingbirds may have the smallest genomes and the highest metabolic rates theoretically possible.

I found this article very interesting.  Hummingbirds are one of my favorite animals and I was intrigued by the genetic links between their genome lengths and metabolic rates.  The proposed relationship between surface-to-volume cell ratio and metabolic rate makes perfect sense and I am curious as to what other organisms also display this relationship.