Fitness consequences of divergent selection on clonal reproduction in a perennial plant
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Authors
Dawson, Kaitlyn
Date
2025-09-17
Type
thesis
Language
eng
Keyword
plant , clonal reproduction , evolution , selection , Mimulus guttatus , field experiment
Alternative Title
Abstract
Most plants can reproduce both sexually and clonally, and the maintenance of dual strategies remains a fundamental dilemma in evolutionary biology. While the balance between strategies favoured by natural selection depends on local environmental conditions, the fitness consequences and evolutionary outcomes of altering reproductive strategies are less clear. Here, I conducted a large-scale field experiment using the model organism Mimulus guttatus (syn. Erythranthe guttata) to investigate the fitness consequences of selection on clonal reproduction. A single perennial population of M. guttatus was subjected to five generations of divergent artificial selection for high or low investment in clonal structures called stolons. The next generation of seeds from these selection lines was planted in naturally heterogeneous field conditions in Sequoia National Park, USA, and monitored from May 2024 to June 2025. I measured a suite of phenotypic traits throughout the growing season and again in the following spring to compare sexual and clonal investment among the selection lines. Additionally, I quantified several environmental parameters to investigate whether vegetation density, soil moisture, or light intensity affects phenotypic trait expression. Consistent with predictions, the high line averaged more stolons and had greater clonal spread, while the low line was more likely to invest in sexual reproduction, with a greater probability of flowering and making more flowers. Although the mean trait values differed among the selection lines, investment in reproductive strategies still varied remarkably within each treatment group. Phenotypic variation is likely maintained, at least in part, by the substantial environmental heterogeneity that plants experience in their natural environment. A redundancy analysis revealed that clonal traits were highly associated with increases in vegetative density and soil moisture, while sexual traits were highly associated with increases in light intensity. Overall, my findings demonstrate that a single population of M. guttatus has the capacity to respond to selection on clonal reproduction and shift patterns of trait allocation in variable environmental conditions. These results underscore the importance of environmental heterogeneity in shaping life history evolution and offer insight into how populations may adaptively respond to dynamic selective pressures in an era of rapid environmental change.
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Intellectual Property Guidelines at Queen's University
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This publication is made available by the authority of the copyright owner solely for the purpose of private study and research and may not be copied or reproduced except as permitted by the copyright laws without written authority from the copyright owner.
Attribution-NonCommercial-NoDerivatives 4.0 International