Mitochondria and sexual selection
Why birds are red? Why do small birds, subject to predation, put colorful and conspicuous pigments in their feathers? Such consideration of ornamental plumage coloration begins with the fundamental question that Darwin and Wallace pondered for decades. Since pigments (mainly carotenoid) cannot be synthesized by birds or other vertebrates; they have to be ingested and moved to the tissue to be pigmented. Most birds eat only yellow pigments and to produce red pigments they have to modify ingested carotenoids from yellow to red. The complexities of this signaling system make it a fascinating focus for study.
Mitochondria are brown. It is very surprising for a mitochondrial biologist to see mitochondria that are red (pictures on the right). we found it is the red-ketolated carotenoids located in the inner hepatic mitochondrial membrane of house finches making mitochondria red. Linking ornamental feather coloration with mitochondrial function suggests a possible solution to a long-standing puzzle in evolutionary biology: what maintains the honesty of signals of individual condition?
We are currently toward understanding how aerobic respiration links to ornament production will be experimental manipulations of mitochondrial function to directly confirm that production of red carotenoid coloration varies with mitochondrial respiration.