Cheating death: Selection on digestive physiology overcomes expected growth costs of anti-predator defenses

Organisms often face a fundamental trade-off between growth and predator
avoidance, especially when traits that enhance growth also increase
predation risk. While many species reduce activity in response to
predators, potentially constraining growth, this trade-off can be
mitigated if alternative traits, such as digestive efficiency, compensate
for reduced activity, enabling organisms to minimize growth costs while
evading predators. To test this idea, we combined a mesocosm experiment
with lab-based digestive physiological assays to examine survival
selection and plasticity in damselfly larvae exposed to fish predators. We
found that selection favored less active individuals, yet this reduction
in activity did not suppress growth. Instead, plastic increases in
consumption rate, selection for greater assimilation efficiency, and
selection for weaker plastic digestive stress responses allowed
individuals to maintain growth despite reduced activity and elevated
metabolic rates. We provide here two datasets related to this study. The
first, titled Mass.Data, contains the data used to determine the ratio of
damselfly wet to dry mass that was necessary for calculating relative
growth rate and other measures of digestive physiology in the experiment.
The second dataset, Assimilation.Data, contains the data for activity
rates, digestive physiology, and all other associated experimental
measurements for comparing selective and plastic responses to predator
presence in damselflies.