Wednesday, February 28, 2018

One in a Million

Earlier this week a yellow cardinal was spotted in Alabama. 
This beautiful bird is rare anomaly bird watchers are flocking to 
Alabama to witness this bird in person. Most people will never get
 the chance to see a yellow cardinal the phenotype is only spotted 
two to three times each year. This yellow phenotype is so rare 
because the color red in birds has been overwhelmingly sexually 
selected for. The theory behind the selection is: the enzyme that
converts yellow pigment to red is located in mitochondria so it is
linked to energy production, thus the red pigment is associated 
with higher fitness. (Lopes et. al. 2016)

 Many birds such as cardinals, flamingos and woodpeckers, 
need to consume pigments known as carotenoids to achieve their 
bright plumage colors. Carotenoids are organic pigments in orange 
foods such as sweet potato, carrots, and apricots. This effect spans 
vertebrate phylum and has been shown to affect salmon and even 
humans: the salmon’s pink colored flesh is result from the 
consumption of carotenoids, and humans’ skin can turn orange from
consuming high levels of beta carotenes (a carotenoid) which is 
commonly found in carrots. (Lopes et. al. 2016) 

This yellow cardinal is likely a knockout mutant for the gene 
that produces CYP2J19 an enzyme for processing beta carotenes.
 CYP2J19 converts the yellow pigments into red feathers.
(Lopes et. al. 2016) CYP2J19 is a ketolase which cleaves
the beta carotene at the keytones changing the compound into canthaxanthin changing the color of this compound from yellow to red. (Lopes et. al. 2016)

While this mutation may not change the fate of 
society, it certainly made many bird watchers’ day. Dramatic
mutations like this that alter an organism’s entire phenotype
are a reminder or just how genetically diverse life is, how
special it is for every living organism in the world to have its
own mostly unique genetic code, and humbles all who realize
the fantastic awe-inspiring process of evolution.

Written By: Brooke Sullivan
Story Inspiration:
Genetic Basis for Red Coloration in Birds
Lopes, Ricardo J. et al.
Current Biology , Volume 26 , Issue 11 , 1427 - 1434


  1. I heard about this yellow cardinal! I had no idea cardinals were any color but red. I wonder how other cardinals interact with this yellow one - if the red cardinals would have a change in behavior based on the physical appearance of the yellow one.

    -- Hannah Kullberg (2)

  2. This is so interesting to read about, I had no idea there was even such thing as a yellow cardinal. It so crazy how this mutation changes the complete color of this bird and how rarely it occurs. It must have been so cool to spot this bird seeing as though they are so rarely mutated into this phenotype.

    Posted by Sarah Aboody (1)

    1. It is quite amazing how rare this mutation occurs. You would think that this would be more common, at least in carndals in captivity because humans enjoy the yellow cardinals so much.

      -Brooke Sullivan

  3. I wonder why the red color is sexually selected for. Why does the red color correlate to a more biologically fit cardinal? Does it have to do with color alone or does the yellow color mean underlying genetic issues?

    Posted by Sarah Kamukala

    1. I do not quite know why it was selected for so consistently but the researchers did mention that they believe it has to do with the fact that that the enzyme CYP2J19 functions in the mitochondria. So perhaps Red cardinals are more efficient energy producers and are more fit this way.

      -Brooke Sullivan

  4. Great post! I think it's interesting that the red pigment is associated with higher fitness and thus impacts the birds' sexual preference. Like how does a red cardinal look at a yellow cardinal and just somehow sense the lower level of fitness? I wonder if it has anything to do with pheromone release. Also, I think you did a great job explaining the mechanisms behind this rare pigmentation phenomenon!

    -Nicole Ayres (1)

  5. As a fellow observer of nature myself, this was a great topic to read up on! I suppose this means that the bird will likely not find a mate as most of its own species will not be attracted to its off-color coat. You mentioned that the yellow is caused by a mutation within the mitochondria - have animals with this
    mutation been known to be less active?

    -Colby Ells (1)