Meta-analysis of behavioural research in lizards reveals that phylogeny and viviparity contribute better to animal personality than secretory glands

Abstract

Animal personality is defined as an individuals behavioural consistency across contexts, situations, and time. Understanding the evolution of animal personality requires the integration of macroevolutionary patterns with intraspecific promoters of individual behavioural consistency. In this study, we conducted a meta-analysis to assess the association between lizards animal personality and different indicators of sociability (a personality promotor) in a phylogenetic context. In lizards, the presence of both, secretory glands and viviparity have been associated with higher sociability levels. We analysed behavioural repeatability data, including 490 effect sizes from 37 species and 63 studies, considering five categories (activity, aggressivity, boldness, exploration, sociability) while controlling for phylogenetic constraints. For each species, we obtained data on the number of secretory glands and the reproductive mode (oviparous or viviparous). The results showed similar values of repeatability for species with and without glands and an absence of correlation between the number of glands and repeatability data. However, higher repeatability was present in viviparous species than in oviparous species. When we conducted separate analyses for each behavioural type, we found two contrasting patterns for exploration and boldness. Species without glands were more exploratory, while species with glands were bolder. In general, phylogeny explained the observed patterns of repeatability, but boldness, exploration and sociability were poorly explained by evolutionary history among species. This study represents a first step in disentangling the integration among animal personality, life-history and morphology traits under a broad evolutionary context.