The effects of costly telomere maintenance on lifespan - reproductive tradeoffs in sand lizards.

Telomeres are DNA-protein structures that primarily protect chromosomes and serve multiple functions of gene regulation. When cells divide, telomeres shorten and their main repair system in ectotherms - telomerase - replaces lost nucleotide complexes ((T2AG3)n in vertebrates). It remains a challenge to experimentally investigate resource requirements for telomere maintenance and its effects on lifespan-reproductive tradeoffs in the wild. In sand lizards (Lacerta agilis), we show that higher female investments into reproduction results in corresponding shortening of telomeres and that males have less frequent and less profound telomere shortening than females; a contributing factor to this may be males' higher telomerase levels. To manipulate resource access for telomere maintenance, we exploit a pseudo-experimental opportunity to analyze 'onboard' resources long-term using lizards that drop their tails with fat and nutrient deposits when attacked by predators. Females with less resources due to regrown tails less often and less profoundly elongate telomeres. Adult lizards with the most TL elongation live the longest, females with the highest lifetime reproductive success shorten telomeres the most, whereas males with the most telomere elongation have the highest lifetime reproductive success. This suggests ongoing evolution of resource-constrained telomere maintenance.