I try not to steal a glance through the lab window each time I pass. But I usually fail. You see, Marco Bisoffi, a molecular biologist and colleague of mine at Chapman, has restarted our study of telomeres* in loons as a possible tool to measure age and the effect of stress. Each week Marco churns out telomere measurements on a new set of loons, as he tries to troubleshoot the PCR** procedure. So when I walk by his lab and see him bent over his laptop, I wonder whether his promising early finding that telomeres indicate age in loons has held up.
It has. Now that Marco has run twelve males and ten females of known age, the trend is stronger than before. If you study the plot above, in fact, two patterns are evident. First, old males and females have shorter telomeres than young males and females. Second, males as a group have shorter telomeres than females. (This latter finding repeats what Jeremy Spool had found a few years ago.) There is some scatter in the data, especially among females, but both patterns show high statistical significance. Of course, we will have an even better fix on these patterns when we have run the other 83 DNA samples we have collected from adults of known age.
It is hard to exaggerate the value of these findings for loon biology and our own research in Wisconsin and Minnesota. There are countless benefits to studying loons, but one drawback has always been our inability to “age” individuals effectively. To our enormous frustration, we cannot even distinguish a 5-year-old from a 30-year-old. If this telomere pattern holds up, however, that source of vexation will be considerably diminished. In the future, we will be able to take a DNA sample from an unknown adult, measure its telomeres, and assign it to an age-class. Indeed, if the unknown bird is a male and we record both its yodel and its tendency to yodel at intruders, we shall be able to narrow its estimated age range still further — probably to within a few years.
Why does it matter that we are on the brink of being able to age adult loons accurately? First, age has a strong effect on a great range of behaviors, including aggressiveness, ability to hold a territory — which increases in young loons and then declines later in life — and even willingness to incubate eggs when black flies are abundant. Second, age impacts survival rate, especially in males. So knowing the ages of loons helps us refine our estimates of survival and improves our models of population dynamics.
Speaking of age and decline, the featured photo for this post is Linda’s Grenzer’s pic of “Clune”, the male on her lake. Despite the inevitable shortening of his telomeres, this 23-year-old still looks pretty fit in his winter attire!
*telomeres — protective DNA sequences (“end caps”) on chromosomes that permit DNA to be replicated many times but become shorter with age and stress
**polymerase chain reaction — a common molecular technique that permits efficient study of specific regions of DNA