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

## TL;DR

Two lizard species maintain consistent learning abilities despite early exposure to stress hormones and temperature changes, and show a natural preference for the color blue.

## Contribution

The study reveals that two lizard species are resilient to prenatal stress and temperature effects on learning, with a novel finding of color preference in decision-making.

## Key findings

- Both lizard species showed similar learning rates regardless of prenatal corticosterone levels or incubation temperature.
- Lizards exhibited a non-learned preference for the color blue, affecting their decision-making.
- The results suggest evolved mechanisms maintain cognitive performance despite early environmental challenges.

## Abstract

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 2 × 2 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.

Animals need to learn to adapt their behavior, but early developmental conditions can limit this ability. Factors like temperature and maternal stress hormones (glucocorticoids) may interact to influence learning, particularly in ectotherms. We studied how glucocorticoids and temperature during incubation affected learning in two lizard species. Surprisingly, both species maintained similar learning rates regardless of treatment, suggesting they could overcome early challenges. Additionally, color influenced their decision-making, highlighting the importance of color in cognitive tests