Exploration and spatial cognition show long-term repeatability but no heritability in the Aegean wall lizard – De Meester et al. 2022
Intro:
To show that a cognitive trait evolves via natural selection then there needs to be evidence that shows the trait is connected to survival and/or reproduction. It also needs to show that the variation in cognition is consistent within individuals hence showing repeatability and heritability. Repeatability is an estimate of how much of the phenotypic variation in a population can be chalked up to consistent individualistic differences. Repeatability is important for cognitive performance or behaviour is important because it sets the upper limit of heritability as in it affects whether and how fast a trait would respond to selection. A recent metanalysis had shown that cognitive performance has low repeatability but this had 3 major limitations. Repeatability is normally tested under short timelines of days or weeks which means the animals may be tested in basically similar conditions temporally so we may be seeing inflated repeatability scores. Most animals tested for this are in lab conditions that do not accurately represent the complexity of their natural environments thus may also be producing high repeatability that is not accurate. Lastly a mix of both reasons, no study has looked at long temporal scales and whether cognition is repeatable in wild environments. This study’s aim was to assess long term repeatability and heritability of spatial cognition, problem solving and exploration within the Aegan wall lizard. They measured personality and cognition of 66 individual lizards in 2019 then released them into a semi-natural enclosure for a survival experiment. They then recaptured the survivors along with their offspring after 1 year and subjected them to the same tests as before.
Methods:
Study Species – original n= 66 individuals of 32 female and 34 male. Survivors were n= 43 of 22 female and 21 male. Juveniles were n=43 and found 21 new adults of 9 female and 12 male.
Housing – animals were kept individually.
Behavioural experiments – did an exploration assay, spatial and reversal learning task and a problem solving task in this order. Animals were charged for 20-30min which means they were allowed to bask for this time underneath a 100W bulb to provide high body temps. Exploration trials were in novel arenas with 4 identical objects in the corners with the presence of shelters. The spatial task was a using antipredator behaviour in combination with a safe shelter so animals would be chased once in the arena and allowed to rest after they reached the safe shelter. The survival task included being released into semi-natural enclosures that were fenced off and terrestrial predators were removed. Some predators could still get in like centipedes and birds but these were minimized by the research team. The semi-natural enclosures also differed in complexity, so some were simple and others had a lot of shrubbery.
Results:
check paper for results I only cared about the charging part of the experiment. This is taken from the abstract We found that exploration and spatial learning were moderately repeatable, but reversal learning only marginally and learning flexibility and problem solving not at all. Reversal learning ability declined over time in lizards kept in simple habitat, but not in those kept in complex habitats e suggesting habitat-dependent cognitive plasticity. To our knowledge, this is the first study demonstrating (long-term) consistency in cognitive traits within a non-avian reptile. The combination of modest repeatability and low heritability does suggest that, within our study species, personality and cognitive variation among individuals and populations is mostly molded by environmental effects.
Al3xandria 