Developmental plasticity in thermal tolerance is insufficient to
compensate for rising temperatures: a meta-analysis
Abstract
Understanding the factors affecting thermal tolerance is crucial for
predicting the impact climate change will have on ectotherms. However,
the role developmental plasticity plays in allowing populations to cope
with thermal extremes is poorly understood. Here, we meta-analyse how
thermal tolerance is acutely and persistently impacted by early thermal
environments by using data from 150 experimental studies on 138
ectothermic species. Thermal tolerance only increased by 0.13°C per 1°C
change in developmental temperature and substantial variation in
plasticity (~36%) was the result of shared evolutionary
history and species ecology. Aquatic ectotherms were more than three
times as plastic as terrestrial ectotherms. Notably, embryos expressed
weaker but more heterogenous plasticity than older life stages, with
numerous responses appearing as non-adaptive. While we did not find
universal evidence for developmental temperatures to have persistent
effects on thermal tolerance, persistent effects were vastly
under-studied, and their direction and magnitude varied with ontogeny.
Embryonic stages may represent a critical window of vulnerability to
changing environments and we urge researchers to consider early life
stages when assessing the climate vulnerability of ectotherms. Overall,
our synthesis suggests that developmental changes in thermal tolerance
will rarely reach levels of perfect compensation and buffer ectotherms
from rising temperatures.