This is a Preprint and has not been peer reviewed. The published version of this Preprint is available: https://doi.org/10.1111/1365-2656.14173. This is version 4 of this Preprint.
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Abstract
Life history tradeoffs are one of the central tenets of evolutionary demography. Tradeoffs, depicting negative covariances between individuals’ life history traits, can arise from genetic constraints, or from a finite amount of resources that each individual has to allocate in a zero-sum game between somatic and reproductive functions. While theory predicts that tradeoffs are ubiquitous, empirical studies have often failed to detect such negative covariances in wild populations. One way to improve the detection of tradeoffs is by accounting for the environmental context, as tradeoff expression may depend on environmental conditions. However, current methodologies usually search for fixed covariances between traits, thereby ignoring their context dependence. Here, we present a hierarchical multivariate ‘covariance reaction norm’ model, adapted from Martin (2023), to help detect context dependence in the expression of life-history tradeoffs using demographic data. The method allows continuous variation in the phenotypic correlation between traits. We validate the model on simulated data for both intraindividual and intergenerational tradeoffs. We then apply it to empirical datasets of yellow-bellied marmots (Marmota flaviventer) and Soay sheep (Ovis aries) as a proof-of-concept showing that new insights can be gained by applying our methodology, such as detecting tradeoffs only in specific environments. We discuss its potential for application to many of the existing long-term demographic datasets and how it could improve our understanding of tradeoff expression in particular, and life history theory in general.
DOI
https://doi.org/10.32942/X2D31R
Subjects
Ecology and Evolutionary Biology, Evolution, Population Biology
Keywords
multivariate, mixed effects, phenotypic correlation, trade-off, life history
Dates
Published: 2023-12-07 09:09
Last Updated: 2024-09-04 11:00
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License
CC BY Attribution 4.0 International
Additional Metadata
Language:
English
Conflict of interest statement:
None
Data and Code Availability Statement:
The data, as well as the R and Stan code necessary to reproduce the results are available on GitHub ( https://github.com/lbiard/detecting_tradeoffs_crn_models ). They will be archived on Zenodo upon acceptance.
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