Within-individual canalization contributes to age-related increases in trait repeatability: a longitudinal experiment in red knots
Kok, E.M.A.; Burant, J.B.; Dekinga, A.; Manche, P.; Saintonge, D.; Piersma, T.; Mathot, K.J. (2019). Within-individual canalization contributes to age-related increases in trait repeatability: a longitudinal experiment in red knots. American Naturalist 194(4). https://dx.doi.org/10.1086/704593Additional data: In: The American Naturalist. George W. Salt/University of Chicago: Salem, Mass.. ISSN 0003-0147; e-ISSN 1537-5323, more |   |
| Author keywords | consistent among-individual differences; variance partitioning; within-individual variation; state-behavior feedbacks |
| Authors | | Top | - Kok, E.M.A., more
- Burant, J.B.
- Dekinga, A., more
- Manche, P.
| - Saintonge, D.
- Piersma, T., more
- Mathot, K.J., more
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| Abstract | Age-related increases in the repeatable expression of labile phenotypic traits are often assumedto arise from an increase in among-individual variance due to differences in developmentalplasticity or by means of state-behavior feedbacks. However, age-related increases inrepeatability could also arise from a decrease in within-individual variance as a result ofstabilizing trait expression, i.e. canalization. Here we describe age-related changes in withinandamong-individual variance components in two correlated traits, gizzard mass andexploration behavior, in a medium-sized shorebird, the red knot (Calidris canutus). Increasedrepeatability of gizzard mass came about due to an increase in among-individual variance,unrelated to differences in developmental plasticity, together with decreases in withinindividualvariance, consistent with canalization. We also found canalization of exploration, butno age-related increase in overall repeatability, which suggests that showing predictableexpression 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 forthe idea that environmental conditions play a key role in generating among-individual variationin both gizzard mass and exploration behavior. Our study shows that stabilization of traitsoccurs under constant conditions: with increased exposure to predictable cues, individuals maybecome more certain in their assessment of the environment allowing traits to becomecanalized. |
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