Journal Article

Within-Individual Canalization Contributes to Age-Related Increases in Trait Repeatability

Saintonge, Darren, Burant, Joseph B., Mathot, Kimberley J., Bell, Alison M., Manche, Petra, Kok, Eva M. A., Dekinga, Anne, Piersma, Theunis, Bolnick, Daniel I.

2019

Overview

Age-related increases in the repeatable expression of labile phenotypic traits are often assumed to arise from an increase in among-individual variance due to differences in developmental plasticity or by means of state-behavior feedbacks. However, age-related increases in repeatability could also arise from a decrease in within-individual variance as a result of stabilizing trait expression, that is, canalization. Here we describe age-related changes in within-individual and among-individual variance components in two correlated traits—gizzard mass and exploration behavior—in a medium-sized shorebird, the red knot (Calidris canutus). Increased repeatability of gizzard mass came about due to an increase in among-individual variance, unrelated to differences in developmental plasticity, together with decreases in within-individual variance consistent with canalization. We also found canalization of exploration but no age-related increase in overall repeatability, which suggests that showing predictable expression of exploration behavior may be advantageous from a very young age onward. Contrasts between juveniles and adults in the first year after their capture provide support for the idea that environmental conditions play a key role in generating among-individual variation in both gizzard mass and exploration behavior. Our study shows that stabilization of traits occurs under constant conditions: with increased exposure to predictable cues, individuals may become more certain in their assessment of the environment allowing traits to become canalized.

• Publisher: University of Chicago Press,The University of Chicago Press,University of Chicago, acting through its Press
• Subject: Adaptation, Physiological / Age / Aging - physiology / Animals / Aquatic birds / Behavior, Animal / Charadriiformes - anatomy & histology / Charadriiformes - physiology / Developmental plasticity / Diet / Environmental assessment / Environmental conditions / Exploration / Exploratory behavior / Female / Gizzard / Gizzard, Avian - anatomy & histology / Knots / Longitude / Male / Organ Size / Plastic properties / Plasticity / Reproducibility