Is most complex trait variation caused by a few common alleles, or is it largely due to the aggregate contributions of many rare variants? How large are per-locus allelic effects on quantitative traits? Is effect size correlated with allele frequency across loci? These are questions of import throughout biology. Mutation- selection balance predicts that polymorphic loci will have rare alleles while balancing selection models predict intermediate allele frequencies. The respective contributions of these evolutionary mechanisms determines the relevance of standing variation to adaptive evolution and the extent to which quantitative trait evolution is limited by mutation as opposed to selection. In human health, the so-called common disease/common variant hypothesis is a statement on these conditions and its validity has clear clinical implications. The proposed studies advance ongoing experiments using the model plant Mimulus guttatus to provide a rigorous exploration of the genetic and ecological factors that maintain genetic variation in natural populations.
The aims are to determine sequence-level determinants of variation in fitness-related traits. This research involves a combination of classical and modern genetics, molecular biology, statistical modeling, and field experimentation. The research should determine not only whether natural selection maintains genetic variation in ecologically important traits, but will begin to elucidate the particular selective agents that are involved.
The third aim also develops a novel procedure for population mapping of quantitative trait loci that is potentially applicable to a broad range of organisms. The proposed studies will train undergraduates, doctoral students, and postdoctoral researchers in each of the four years of the project.

Public Health Relevance

The proposed studies directly investigate the genetic architecture of complex traits. Most chronic human diseases are complex traits and the dissection of genetic causes is a major research focus of the National Institutes of Health. Our experiments on the model plant Mimulus guttatus provide relevant results and 'proof-of-concept'of genetic methods for future health-related research.

National Institute of Health (NIH)
National Institute of General Medical Sciences (NIGMS)
Research Project (R01)
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Genetic Variation and Evolution Study Section (GVE)
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Eckstrand, Irene A
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University of Kansas Lawrence
Schools of Arts and Sciences
United States
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Brown, K E; Kelly, J K (2018) Antagonistic pleiotropy can maintain fitness variation in annual plants. J Evol Biol 31:46-56
Wessinger, Carolyn A; Kelly, John K; Jiang, Peng et al. (2018) SNP-skimming: A fast approach to map loci generating quantitative variation in natural populations. Mol Ecol Resour 18:1402-1414
Troth, Ashley; Puzey, Joshua R; Kim, Rebecca S et al. (2018) Selective trade-offs maintain alleles underpinning complex trait variation in plants. Science 361:475-478
Nelson, Thomas C; Monnahan, Patrick J; McIntosh, Mariah K et al. (2018) Extreme copy number variation at a tRNA ligase gene affecting phenology and fitness in yellow monkeyflowers. Mol Ecol :
Colicchio, J (2017) Transgenerational effects alter plant defence and resistance in nature. J Evol Biol 30:664-680
Monnahan, Patrick J; Kelly, John K (2017) The Genomic Architecture of Flowering Time Varies Across Space and Time in Mimulus guttatus. Genetics 206:1621-1635
Puzey, Joshua R; Willis, John H; Kelly, John K (2017) Population structure and local selection yield high genomic variation in Mimulus guttatus. Mol Ecol 26:519-535
Koseva, Boryana; Crawford, Daniel J; Brown, Keely E et al. (2017) The genetic breakdown of sporophytic self-incompatibility in Tolpis coronopifolia (Asteraceae). New Phytol 216:1256-1267
Case, Andrea L; Finseth, Findley R; Barr, Camille M et al. (2016) Selfish evolution of cytonuclear hybrid incompatibility in Mimulus. Proc Biol Sci 283:
Lee, Young Wha; Fishman, Lila; Kelly, John K et al. (2016) A Segregating Inversion Generates Fitness Variation in Yellow Monkeyflower (Mimulus guttatus). Genetics 202:1473-84

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