COSAM Professors Link Bird Coloration to Bird Quality
Auburn University Biological Sciences professor Dr. Geoffrey Hill has studied red coloration in birds for much of his career. During his doctoral dissertation, he showed there was a link between the redness of male bird’s feathers and exceptional traits such as a better immune system and lower stress levels.
After nearly 30 years of research, Hill and a team, which consists of Biological Sciences associate professor Dr. Wendy Hood and Dr. Andreas Kavazis’s Lab in the Department of Kinesiology, have produced a groundbreaking study that presents an intriguing new explanation for how the pigments in a bird’s feathers could signal the quality of the bird. Their discovery was summarized in a paper entitled “Plumage redness signals mitochondrial function in the House Finch” recently published by the scientific journal Proceedings of the Royal Society London, B.
The paper proposes that the production of red pigments by birds is biochemically linked to the function of mitochondria. They provide evidence that red pigments are produced within the mitochondria of finches and that the process of pigmentation may be directly linked to core respiratory processes. Because the mitochondrion is the powerhouse of the cell, a link between pigmentation and mitochondrial function potentially explains the link between red feathers and male quality.
“We really wanted to know how a simple signal could capture the overall quality of an individual bird,” Dr. Hill explained. “It makes sense that if the signal is a product of basic cellular processes like respiration, then the signal would reflect the overall quality of the individual. Also, a link between redness and mitochondrial function would mean that when females choose sexy red males as mates, they are selecting for high mitochondrial function. Many human diseases arise from mitochondrial dysfunction, so this research has implications for biomedicine.”
In his dissertation work, Hill showed that House Finches do not eat red pigments, but eat yellow pigments that they convert into red pigments.
“That conversion turned out to be key,” Dr. Hill explained. “We found the gene that allows this conversion and knowing that gene pointed us towards the mitochondria. There were suggestions that bioconversion might take place in the mitochondria, which led to a set of hypotheses that the production of red pigments might be directly linked to the mitochondria. At that point I was stuck because those are biochemical physiology hypotheses that I had no ability to test.”
This is where Dr. Hood and Dr. Kavazis could help. Dr. Hood’s research is focused on mitochondrial physiology, so her lab had the tools to measure mitochondrial function. Dr. Kavazis and Dr. Hood have worked together for years.
“He’s the mitochondrial guru,” Dr. Hill said of Dr. Kavazis. “That’s why the work goes on in his lab.”
With the right team, the data collection and testing for the paper took less than a year. Dr. Hill and Dr. Hood said the reaction from the scientific community has been exciting.
“No one was looking at mitochondria, but they are now,” Dr. Hill said. “We are getting a lot of people interested in mitochondria as a key player in sexual selection and speciation.”
Dr. Hood added that she believes this research is going to change how scientists think about sexual selection.
“No one has looked at mitochondria previously and it just makes a lot of sense that the energy production of cells would underlie ornamentation,” she said. “Consider the antlers of deer. They are produced in only a few weeks, requiring a huge input of energy for bone growth. Mitochondrial performance would logically underlie the production of the largest antlers.”