Cognitive processes are robust to early environmental conditions in two lizard species

Animals must acquire new information through learning to adjust their
behavior adaptively. However, learning ability can be constrained by
conditions experienced during early development, when the brain is
especially susceptible to environmental conditions. For example,
temperature can result in phenotypically plastic adjustments to growth,
metabolism, and learning in ectotherms. In vertebrates, thermal conditions
can increase the production of glucocorticoid (GCs) - ‘stress’ hormones.
Maternal GCs can be transmitted to offspring during development,
potentially impacting their learning abilities. GCs and thermal
environments are, therefore, predicted to have interactive effects on the
development of learning in ectotherms. Here, we investigated the combined
effects of prenatal corticosterone (CORT) - the main GC in reptiles - and
incubation temperature on associative learning using two species of
lizards, Lampropholis delicata and L. guichenoti. We manipulated CORT
levels and temperature in a 2x2 factorial design, and then subjected
juveniles to a color-associative learning task. We predicted that elevated
CORT and low temperatures would impair associative learning. However, both
species showed similar learning rates independently of treatment. Our
results suggest that these two species may have evolved mechanisms to
maintain learning performance despite prenatal challenges. We also found
that color affected decision-making in both species. Overall, we observed
a non-learned preference towards blue, underscoring the need to carefully
select the color used in cognitive tests involving visual stimuli.