Early social context does not influence behavioral variation at adulthood in ants

Abstract

Early experience can prepare offspring to adapt their behaviors to the environment they are likely to encounter later in life. In several species of ants, colonies show ontogenic changes in the brood-to-worker ratio that are known to have an impact on worker morphology. However, little information is available on the influence of fluctuations in the early social context on the expression of behavior in adulthood. Using the ant Lasius niger, we tested whether the brood-to-worker ratio during larval stages influenced the level of behavioral variability at adult stages. We raised batches of 20 or 180 larvae in the presence of 60 workers until adulthood. We then quantified the activity level and wall-following tendency of callow workers on ten successive trials to test the prediction that larvae reared under a high brood-to-worker ratio should show greater behavioral variations. We found that manipulation of the brood-to-worker ratio influenced the duration of development and the size of individuals at emergence. We detected no influence of early social context on the level of between- or within individual variation measured for individual activity level or on wall-following behavior. Our study suggests that behavioral traits may be more canalized than morphological traits.

Direct and cross-generational effects of reproduction on fitness and behavioral variability in male-biased environments

“…The fact that sex-ratio and development time of the offspring were not affected by the environment experienced by the mothers, but their behavior was, points to behavior as a more plastic phenotypic trait in contrast to lifespan traits (however, the opposite was found in other experiments working with I. graellsii , Debecker et al 2016 ; or ants, Sanmartín-Villar and Jeanson 2021 ). Our results suggest that male-biased ratios modify reproductive strategies with potential consequences in population dynamics as well as highlight the relevance of considering personality traits when studying reproduction costs across generations.…”

“…Interindividual differences in plasticity within the experimental treatments was calculated by comparing models with and without the repeated tests as random slope and the individual ID as random intercept. Models were selected using AIC to unravel if the variability in the data was better explained considering or not considering repeated tests as random slope, that is, if individuals performed different behavioral patterns through the time or not (see also Sanmartín-Villar et al 2021 ; Sanmartín-Villar and Jeanson 2021 ).…”