Figure 1.

Declining TL with increasing age in purple-crowned fairy-wrens. A significant nonlinear relationship between relative telomere length (rTL) and age as shown by generalized additive mixed models (GAMMs) can be well approximated by log age (electronic supplementary material, table S2). Fitted values show standardized rTL predicted by log age in a linear mixed model (LMM), and back-transformed to the original age scale, with the ribbon showing 95% confidence intervals, incorporating uncertainty from all fixed effects in the LMM.