Among-year variation in the repeatability, within- and between-individual, and phenotypic correlations of behaviors in a natural population

Abstract

When mean behaviors correlate among individuals, they form behavioral syndromes. One way to understand the evolution of such a group-level phenomenon is to compare horizontally patterns of correlations among populations (or species) or follow longitudinally the same population over years in the light of parallel differences in the environment. We applied the longitudinal approach to 8-year field data and analyzed phenotypic correlations, and their within- and between-individual components, among three behaviors (novelty avoidance, aggression, and risk-taking) in male collared flycatchers, Ficedula albicollis, in a meta-analytic framework. The phenotypic correlation between novelty avoidance and aggression varied heterogeneously (it was positive in some years, while it was negative in other years), while the other pair-wise correlations were consistently positive over the study period. We investigated four potential socio-ecological factors, and found evidence that the among-year alterations in the demographic structure of the population (density, age composition) can be responsible for the heterogeneous effect sizes. Comparing within- and between-individual correlations across pairs of traits, we found that the correlation between aggression and risk-taking at the among-individual level was the strongest suggesting that this relationship has the highest potential to form a behavioral syndrome. Within-year repeatabilities varied among traits, but were systematically higher than between-year repeatabilities. Our study highlights on an empirical basis that there can be several biological and statistical reasons behind detecting a phenotypic correlation in a study, but only few of these imply that fixed behavioral syndromes are maintained in a natural population. In fact, some correlations seem to be shaped by environmental fluctuations.

Repeatability and reliability of exploratory behavior in proactive and reactive zebrafish, Danio rerio

“…While these studies examined between-population differences, similar patterns have been observed within populations across time in collared flycatcher birds ( Ficedula albicollis ). Behavioral correlations appeared and disappeared across years that coincided with changes in the density and age composition of the bird population, which could reflect changes in resource availability 65 . Our results suggest that the ecological pressures acting on the WC population shaped different behavioral patterns compared to those resulting from artificial selection.…”

“…The local ecological factors that might have contributed to shaping the WC animals’ behavior are not known. It is possible that some population differences or behavioral correlations may only emerge under certain local environmental conditions 16,46,65 . Several studies that investigated wild zebrafish populations found that predation and water flow can explain population differences in behavioral correlations between boldness, aggression and activity 16,46 .…”

Experience during development triggers between‐individual variation in behavioural plasticity

“…Garamszegi et al. () studying a wild population of collared flycatchers ( Ficedula albicollis ) demonstrated that strength and direction of behavioural correlations could change among years. In manipulative experiments, Horváth, Martín, López, Garamszegi, and Herczeg () and Horváth, Mészáros, et al.…”

Partitioning within‐species variance in behaviour to within‐ and between‐population components for understanding evolution

“…; Møller ) or low (Garamszegi et al . 2015a) repeatability. Therefore, we cannot exclude that some amount of the within‐population variance originates from within‐individual plasticity, at least in some species.…”