Unraveling the roles of genotype and environment in the expression of plant defense phenotypes. Issue 13 (8th June 2021)

• Record Type: Journal Article
• Authors: Potts, Abigail S.; Hunter, Mark D.
• Is Part Of: Ecology and evolution. Volume 11:Issue 13(2021)
• Page Start: 8542
• Page End: 8561
• Publication Date: 2021-06-08
• Subjects: cardenolides -- defoliation -- genetic variation -- genotype‐by‐environment interactions -- latex -- milkweed -- plant defense -- resistance traits; Ecology -- Periodicals; Evolution -- Periodicals; 577.05
• DOI: 10.1002/ece3.7639
• Languages: English
• ISSNs: 2045-7758

Abstract

Abstract: 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, Asclepias syriaca, in northern Michigan. We first measured resistance and resistance traits of 14 maternal lines in two common garden experiments (field and greenhouse) to detect genetic variation within the population. We carried out a reciprocal transplant experiment with three of these maternal lines to assess effects of local environment on phenotype. Finally, we compared the phenotypic traits measured in our experiments with the phenotypic traits of the naturally growing maternal genets to be able to compare relative effect of genetic and environmental variation on naturally occurring phenotypic variation. We measured defoliation levels, arthropod abundances, foliar cardenolide concentrations, foliar latex exudation, foliar carbon and nitrogen concentrations, and plant growth. 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. Abstract : This study explores how local growing environment and genetic variation dictates plant trait expression within a small population. We measured within‐population genetic variation in resistance traits of common milkweed and then compared those traits with patterns of resistance in the naturally growing milkweed population. Our findings suggest that genotype‐by‐environment interactions and environmental variation strongly influence phenotypic expression in this population of common milkweed and that standing genetic variation alone has a limited role in phenotypic variation.