Egg incubation effects generate positive correlations between size, speed and learning ability in young lizards

Area of Science:

• Evolutionary Biology
• Herpetology
• Behavioral Ecology

Background:

• Reptilian body size and locomotor performance are considered targets of Darwinian selection.
• Phenotypic plasticity in response to incubation temperature may explain trait variation, masking genetic influences.
• Incubation temperature could also impact cognitive traits like learning ability in reptiles.

Purpose of the Study:

• To investigate correlations between body size, locomotor speed, and learning ability in lizards.
• To determine if incubation temperature influences these correlated traits.
• To assess the role of environmental effects versus genetic variation in trait correlations.

Main Methods:

• Lizard eggs (Bassiana duperreyi) were incubated under hot and cold thermal regimes.
• Hatchling body size and running speed were measured.
• Learning ability was assessed using a Y-maze with a food reward, quantifying time to solution and route directness.

Main Results:

• High positive correlations were found between body size, running speed, and learning ability.
• These correlations were demonstrated to be caused by environmental effects of incubation temperature.
• Both metrics for learning ability (time to solution, route directness) showed these strong correlations.

Conclusions:

• Environmental factors during incubation, specifically temperature, create correlations between size, speed, and learning in lizards.
• These findings challenge interpretations of fitness advantages solely based on size or speed.
• Observed differences in survival may be linked to learning ability, mediated by incubation conditions, rather than size or speed alone.