Age determination in individual wild-caught Drosophila serrata using pteridine concentration.
Fluorescence spectrophotometry can reliably detect levels of the pteridine 6-biopterin in the heads of individual Drosophila serrata Malloch 1927. Pteridine content in both laboratory and field captured flies is typically a level of magnitude higher than the minimally detectable level (mean(lab)=0.54 units, mean(field)=0.44 units, minimum detectable level=0.01 units) and can be used to predict individual age in laboratory populations with high certainty (r2=57%). Laboratory studies of individuals of known age (from 1 to 48 days old) indicate that while pteridine level increases linearly with age, they also increase in a linear manner with rearing temperature and ambient light levels, but are independent of sex. As expected, the longevity of laboratory-reared males (at least 48 days) is higher than the range of predicted ages of wild-caught males based on individual pteridine levels (40 days). However, the predictive equation based on pteridine level alone suggested that a number of wild-caught males were less than 0 days old, and the 95% confidence limits for these predictions based on the inverse regression are broad. The age of the oldest wild-caught male is predicted to fall within the range of 2 to 50 days. The significant effects of temperature and light intensity determined in the laboratory study (effect sizes omega2=14.3 and 20.4%, respectively) suggests that the calibration of the age prediction equation for field populations would be significantly improved when combined with fine-scaled studies of habitat temperature and light conditions. The ability to determine relative age in individual wild-caught D. serrata presents great opportunities for a variety of evolutionary studies on the dynamics of natural populations.
Robson
Simon K A
SK
School of Tropical Biology, James Cook University, Townsville QLD 4812, Australia. Simon.Robson@jcu.edu.au
Vickers
Mathew
M
Blows
Mark W
MW
Crozier
Ross H
RH
D000375:Aging; D000818:Animals; D001708:Biopterins / Q000032:analysis* / Q000378:metabolism; D004330:Drosophila / Q000254:growth & development* / Q000378:metabolism; D004772:Entomology / Q000379:methods; D005260:Female; D006257:Head / Q000502:physiology; D008027:Light; D008297:Male; D013696:Temperature
D001708:Biopterins