Seychelles warblers with silver spoons: juvenile condition is a lifelong
predictor of annual survival, but not annual reproduction or senescence
Abstract
1) The environment experienced during development, and its impact on
intrinsic condition, can have lasting outcomes for adult phenotypes and
could contribute to the individual variation in senescence trajectories.
2) However, the nature of this relationship in wild populations remains
uncertain, owing to the difficulties in summarizing environmental
complexity and long-term monitoring of individuals from free-roaming
long-lived species. 3) In this study, we determine whether juvenile
condition (derived from measures of body mass and size) is associated
with senescence-related traits of a closely monitored population of
Seychelles warblers (Acrocephalus sechellensis). 4) Juveniles with a
higher condition index were more likely to survive to adulthood –
suggesting these juveniles experienced better developmental conditions.
Furthermore, these juveniles as adults were in better condition and had
higher rates of annual survival, independently of age. In contrast,
there was no association between juvenile condition and declines in
adult telomere length (a measure of somatic stress) nor annual
reproduction. 5) These results indicate that juvenile condition, while
not associated with senescence trajectories, can influence the
likelihood of surviving to old age due to silver-spoon effects. This
study shows that measures of intrinsic condition in juveniles can
provide important insights into long-term fitness of individuals in wild
populations.