REID, A.M.; HAUSSMANN, M.F.; BRONIKOWSKI, A.M.; VLECK, C.M.; Iowa State University; Iowa State University; Iowa State University; Iowa State University: Age determination using average telomere length and bone growth rings in the western terrestrial garter snake (Thamnophis elegans).

Determining the age structure of populations is essential to our understanding of population dynamics and life-history variation. To date, determining an individual�s age has relied on long-term, mark-recapture studies of neonates. We evaluate a new non- lethal method for determining the age of garter snakes using telomere length and compare this estimate to annual bone growth rings (skeletochronology). Telomeres generally shorten with consecutive cell divisions and the rate of change in erythrocyte telomere length has been suggested as a predictor of age in some bird species. Skeletochronology uses the number of annual bone growth arrest lines (due to hibernation) to estimate age. To test the accuracy of the telomere method for determining snake age, we collected blood samples and tail tips from 30 individuals from a long-term monitoring site in Lassen County, California. Radioactive telomere-specific probes and optical densitometry were used to determine the average erythrocyte telomere restriction fragment (TRF) lengths and the mean number of bone growth rings was counted from histological sections of each individuals tail tip. The accuracy of the telomere technique for determining age was then evaluated. Preliminary results indicate a relationship between average telomere length and the number of growth rings for snakes. We discuss the relevance of this result for the construction of age-specific vital rates and for the possible role that telomere shortening has in cellular senescence and the senescent phenotype.