HAUSSMANN, M.F.; WINKLER, D.W.; VLECK, C.M.; Iowa State Univ.; Cornell Univ.; Iowa State Univ.: Longer telomeres may confer an individual survival advantage in a wild bird

Elucidating factors that influence survival in wild populations has been a major thrust of physiological ecology. Telomeres are the terminal caps on all eukaryotic chromosomes. During normal aging loss of telomeres contributes to cellular senescence. Furthermore, the interspecific rate of telomere loss is correlated with species maximum life span. To determine whether initial telomere length is correlated with survival, we measured telomere lengths in a group (n = 8) of 1-yr-old female tree swallows (Tachycineta bicolor) in 2003 and then tracked their return rates to the Ithaca, NY colonies in 2004. These birds show high site fidelity as adults and non-return is probably due to mortality. Mean telomere restriction fragment (TRF) length was measured by separating digested erythrocyte DNA in a pulsed-field electrophoresis system. Of females with TRFs shorter than the median value, 25% returned in 2004, whereas in females with TRFs longer than the median value, 75% returned. We also have data from 10 additional females initially caught as one-year olds and telomeres measured in 2001 for which we have return rates over the next three years. Of those females with TRFs shorter than the median value, 40% returned in 2002, and none returned in 2003 and 2004. In females with TRFs longer than the median value, 100% returned in 2002, 80% returned in 2003, and 20% returned in 2004. Thus, survival in female tree swallows appears to be correlated with initial TRF length. These results are preliminary because sample sizes are small, but they suggest that individuals with initially short telomere length may be at an inherent disadvantage. We are now tracking survival of 100 1-yr-old females with known TRF lengths to test this hypothesis.