Phenotypic variability results from interactions between genotype and environment and is a major driver of ecological and evolutionary interactions. Measuring the relative contributions of genetic variation, the environment, and their interaction to phenotypic variation remains a fundamental goal of evolutionary ecology. In this study, we assess the question: How do genetic variation and local environmental conditions interact to influence phenotype within a single population? We explored this question using seed from a single population of common milkweed, We found a striking lack of correlation in trait expression of the maternal lines between the common gardens, or between the common gardens and the naturally growing maternal genets, suggesting that environment plays a larger role in phenotypic trait variation of this population. We found evidence of significant genotype‐by‐environment interactions for all traits except foliar concentrations of nitrogen and cardenolide. Milkweed resistance to chewing herbivores was associated more strongly with the growing environment. We observed no variation in foliar cardenolide concentrations among maternal lines but did observe variation among maternal lines in foliar latex exudation. Overall, our data reveal powerful genotype‐by‐environment interactions on the expression of most resistance traits in milkweed.
Leaf economic spectrum (LES) theory has historically been employed to inform vegetation models of ecosystem processes, but largely neglects intraspecific variation and biotic interactions. We attempt to integrate across environment–plant trait–herbivore interactions within a species at a range‐wide scale.
We measured traits in 53 populations spanning the range of common milkweed (
Trait–trait relationships largely followed interspecific patterns in LES theory and persisted in a common garden when individual traits change. Common milkweed showed intraspecific variation and biogeographic clines in traits. Clines did not persist in a common garden. Larvae ate more and grew larger when fed plants with more nitrogen. A longitudinal environmental gradient in precipitation corresponded to a resource gradient in plant nitrogen, which produces a gradient in larval performance.
Biogeographic patterns in common milkweed traits can sometimes be predicted from LES, are largely driven by environmental conditions, and have consequences for monarch larval performance. Changes to nutrient dynamics of landscapes with common milkweed could potentially influence monarch population dynamics. We show how biogeographic trends in intraspecific variation can influence key ecological interactions, especially in common species with large distributions.
- NSF-PAR ID:
- 10452424
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- American Journal of Botany
- Volume:
- 108
- Issue:
- 3
- ISSN:
- 0002-9122
- Page Range / eLocation ID:
- p. 388-401
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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