Influence Of Maternal Aggression And Stress Response On Offspring Quality In Tree Swallows

ASU Author/Contributor (non-ASU co-authors, if there are any, appear on document)
Kimberly Rebecca Todd (Creator)
Appalachian State University (ASU )
Web Site:
Lynn Siefferman

Abstract: Mounting evidence suggests wild animals possess unique personalities that, while consistent within individuals, differ across individuals in the population. Conversely, the glucocorticoid profiles of animals can show high within-individual plasticity. The repeatability of some traits coupled with the degree to which other traits vary across time and contexts should be considered complementary aspects of animals’ coping styles. Behavior-physiology interactions and their fitness consequences have only recently surfaced in the literature, yet these phenotypic combinations are heritable, fitness-related, and shaped by evolutionary forces and thus represent an adaptive strategy for coping in a dynamic environment. A behavioral reaction norm (BRN) is a modelling approach used to quantify the degree of within- and between-individual personality (‘intercept’) and plasticity (‘slope’). We use a 3-year dataset collected on a breeding population of tree swallows (Tachycineta bicolor) in the southern Appalachians to assess how female personality (nest defense aggression) and glucocorticoid plasticity (baseline corticosterone/CORT slope) interact to influence offspring quality across multiple years. We found that females with aggressive and nonaggressive personalities adjusted baseline CORT differently across the breeding stage. Nonaggressive females tended to experience increased baseline CORT from the early to late nestling stage, consistent with a ‘cost of reproduction,’ whereas aggressive females did not. Personality alone did not predict reproductive success, but there was a personality-by-CORT-slope interaction. Baseline CORT slope predicted nestling quality, but only among aggressive females which maintained a constant level of baseline CORT in 2015 and reduced baseline CORT in 2016. Overall, our results suggest that aggressive females can produce high-quality young without enduring a physiological ‘cost of reproduction.’ Comparable fitness despite differences in glucocorticoid plasticity among females of different personalities may be driven by changing environmental contexts, individual attributes, and unique physiological optima that aid individuals in striking a personalized balance between energy use and allocation to offspring.

Additional Information

Honors Project
Todd, K. (2020). Influence Of Maternal Aggression And Stress Response On Offspring Quality In Tree Swallows. Unpublished Honors Thesis. Appalachian State University, Boone, NC.
Language: English
Date: 2020
personality, coping style, reproductive success, corticosterone

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