The Beautifully Deadly Hummingbird

An article in the New York Times website discusses the all too aggressive side to hummingbirds.  These beautiful birds are much more than tiny bright color birds, for they have an aggressive side that is quite deadly.  Hummingbird evolution was sparked by the evolution of plants needing a better method of being pollinated.  This had a direct evolution with the hummingbird and its bill, but that bill much soon became more than a means to eating.

Behold the bill of the male tooth-billed hummingbird; not so cute anymore is it?  This hummingbird has been used as a symbol of the gods in the Aztec civilization due to its aggressive nature.  Their bills are used for eating, but also used to fight other hummingbirds as a means of  sexual selection.  This is a trait in both male and female hummingbirds, but the fascinating thing is the shape of the bill is literally used to impale other birds.  The science behind its eating is being vastly researched by Dr. Rico-Guevara and Margaret A. Rubega as a joint study to learn more about the tongues that hide inside this deadly bill.

A single gene influences petunia pollinators

An international research team has discovered the mutations of the MYB-FL gene and the role it plays of floral UV absorbance and coloration in petunias. The MYB-FL gene is a single gene that accounts for the attraction of nocturnal pollinators. The variation of the gene allows for the fluctuations of Flavonol and anthocyanin. Flavonol controls the dimming or stimulation of the UV light intensity while anthocyanin is a pigment compound that controls flower color. 

            The mutation of the MYB-FL gene could mean the difference between which insect/animal pollinates the plant’s flower. Researchers found UV and pigment differences among three different petunia flowers correspond to differences in their pollinators. Some nocturnal moths had tended to draw near flowers with much UV absorption, such as the white flowers of P. axillaris. Bees enjoy the small, purple flowers of P. inflata. In the daytime, hummingbirds visit the bright red flower P. exserta that absorbs much less UV light.

            It was interesting to read how plants can pick their pollinators. Each petunia was different in their means of UV absorption and coloration. This, of course, depended upon the accumulation of flavonoid pigments in the plants. The P. exserta, for instance, primarily attracts hummingbirds. This bright red flower draws the bird to its stigmas and stamens for pollination.

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.