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John H. Willis

Professor of Biology
Biology
Box 90338, Department of Biology, Durham, NC 27708-0338
3314 French Science Center, Science Drive, Durham, NC 27708

Selected Publications


The genetic basis of traits associated with the evolution of serpentine endemism in monkeyflowers.

Journal Article Evolution; international journal of organic evolution · January 2024 The floras on chemically and physically challenging soils, such as gypsum, shale, and serpentine, are characterized by narrowly endemic species. The evolution of edaphic endemics may be facilitated or constrained by genetic correlations among traits contri ... Full text Cite

Beyond Content, Understanding What Makes Test Questions Most Challenging

Journal Article BioScience · March 1, 2023 When students answer test questions incorrectly, we often assume they don’t understand the content; instead, they may struggle with certain cognitive skills or with how questions are asked. Our goal was to look beyond content to understand what makes asses ... Full text Cite

The genetic architecture and evolution of life-history divergence among perennials in the Mimulus guttatus species complex.

Journal Article Proceedings. Biological sciences · April 2021 Ecological divergence is a fundamental source of phenotypic diversity between closely related species, yet the genetic architecture of most ecologically relevant traits is poorly understood. Differences in elevation can impose substantial divergent selecti ... Full text Cite

Populations Are Differentiated in Biological Rhythms without Explicit Elevational Clines in the Plant Mimulus laciniatus.

Journal Article Journal of biological rhythms · October 2020 Environmental variation along an elevational gradient can yield phenotypic differentiation resulting from varying selection pressures on plant traits related to seasonal responses. Thus, genetic clines can evolve in a suite of traits, including the circadi ... Full text Cite

Patterns of Hybrid Seed Inviability in the Mimulus guttatus sp. Complex Reveal a Potential Role of Parental Conflict in Reproductive Isolation.

Journal Article Current biology : CB · January 2020 Genomic conflicts may play a central role in the evolution of reproductive barriers. Theory predicts that early-onset hybrid inviability may stem from conflict between parents for resource allocation to offspring. Here, we describe M. decorus: a group of c ... Full text Cite

Developmental Analysis of Mimulus Seed Transcriptomes Reveals Functional Gene Expression Clusters and Four Imprinted, Endosperm-Expressed Genes.

Journal Article Frontiers in plant science · January 2020 The double fertilization of the female gametophyte initiates embryogenesis and endosperm development in seeds via the activation of genes involved in cell differentiation, organ patterning, and growth. A subset of genes expressed in endosperm exhibi ... Full text Cite

Dissecting the role of a large chromosomal inversion in life history divergence throughout the Mimulus guttatus species complex.

Journal Article Molecular ecology · March 2019 Chromosomal inversions can play an important role in adaptation, but the mechanism of their action in many natural populations remains unclear. An inversion could suppress recombination between locally beneficial alleles, thereby preventing maladaptive res ... Full text Cite

Hybrid inviability and differential submergence tolerance drive habitat segregation between two congeneric monkeyflowers.

Journal Article Ecology · December 2018 Closely related, ecologically similar species are often separated at small geographic scales while being broadly sympatric. Both adaptation to abiotic environmental conditions and a variety of biotic interactions may determine small-scale allopatry. In Nor ... Full text Cite

Major QTL controls adaptation to serpentine soils in Mimulus guttatus.

Journal Article Molecular ecology · December 2018 Spatially varying selection is a critical driver of adaptive differentiation. Yet, there are few examples where the fitness effects of naturally segregating variants that contribute to local adaptation have been measured in the field. Plant adaptation to h ... Full text Cite

Selective trade-offs maintain alleles underpinning complex trait variation in plants.

Journal Article Science (New York, N.Y.) · August 2018 To understand evolutionary factors that maintain complex trait variation, we sequenced genomes from a single population of the plant Mimulus guttatus, identifying hundreds of nucleotide variants associated with morphological and life history traits. ... Full text Cite

Dramatic evolution of body length due to postembryonic changes in cell size in a newly discovered close relative of Caenorhabditis elegans

Journal Article Evolution Letters · August 1, 2018 Understanding morphological diversity—and morphological constraint—has been a central question in evolutionary biology since its inception. Nematodes of the genus Caenorhabditis, which contains the well-studied model organism C. elegans, display remarkable ... Full text Cite

Differential adaptation to a harsh granite outcrop habitat between sympatric Mimulus species.

Journal Article Evolution; international journal of organic evolution · June 2018 Understanding which environmental variables and traits underlie adaptation to harsh environments is difficult because many traits evolve simultaneously as populations or species diverge. Here, we investigate the ecological variables and traits that underli ... Full text Cite

Plastic breeding system response to day length in the California wildflower Mimulus douglasii.

Journal Article American journal of botany · April 2018 Premise of the studyAngiosperms have evolved multiple breeding systems that allow reproductive success under varied conditions. Striking among these are cleistogamous breeding systems, where individuals can produce alternative flower types special ... Full text Cite

Population-genomic inference of the strength and timing of selection against gene flow.

Journal Article Proceedings of the National Academy of Sciences of the United States of America · July 2017 The interplay of divergent selection and gene flow is key to understanding how populations adapt to local environments and how new species form. Here, we use DNA polymorphism data and genome-wide variation in recombination rate to jointly infer the strengt ... Full text Cite

Geographic Variation of Plant Circadian Clock Function in Natural and Agricultural Settings.

Journal Article Journal of biological rhythms · February 2017 The increasing demand for improved agricultural production will require more efficient breeding for traits that maintain yield under heterogeneous environments. The internal circadian oscillator is essential for perceiving and coordinating environmental cu ... Full text Cite

The genetic architecture of local adaptation and reproductive isolation in sympatry within the Mimulus guttatus species complex.

Journal Article Molecular ecology · January 2017 The genetic architecture of local adaptation has been of central interest to evolutionary biologists since the modern synthesis. In addition to classic theory on the effect size of adaptive mutations by Fisher, Kimura and Orr, recent theory addresses the g ... Full text Cite

Population structure and local selection yield high genomic variation in Mimulus guttatus.

Journal Article Molecular ecology · January 2017 Across western North America, Mimulus guttatus exists as many local populations adapted to site-specific environmental challenges. Gene flow between locally adapted populations will affect genetic diversity both within demes and across the larger metapopul ... Full text Cite

Disruption of endosperm development is a major cause of hybrid seed inviability between Mimulus guttatus and Mimulus nudatus.

Journal Article The New phytologist · May 2016 Divergence of developmental mechanisms within populations could lead to hybrid developmental failure, and might be a factor driving speciation in angiosperms. We investigate patterns of endosperm and embryo development in Mimulus guttatus and the closely r ... Full text Cite

A Segregating Inversion Generates Fitness Variation in Yellow Monkeyflower (Mimulus guttatus).

Journal Article Genetics · April 2016 Polymorphic chromosomal rearrangements can bind hundreds of genes into single genetic loci with diverse effects. Rearrangements are often associated with local adaptation and speciation and may also be an important component of genetic variation within pop ... Full text Cite

The genetic basis of traits associated with the evolution of serpentine endemism in monkeyflowers.

Journal Article Evolution; international journal of organic evolution · January 2024 The floras on chemically and physically challenging soils, such as gypsum, shale, and serpentine, are characterized by narrowly endemic species. The evolution of edaphic endemics may be facilitated or constrained by genetic correlations among traits contri ... Full text Cite

Beyond Content, Understanding What Makes Test Questions Most Challenging

Journal Article BioScience · March 1, 2023 When students answer test questions incorrectly, we often assume they don’t understand the content; instead, they may struggle with certain cognitive skills or with how questions are asked. Our goal was to look beyond content to understand what makes asses ... Full text Cite

The genetic architecture and evolution of life-history divergence among perennials in the Mimulus guttatus species complex.

Journal Article Proceedings. Biological sciences · April 2021 Ecological divergence is a fundamental source of phenotypic diversity between closely related species, yet the genetic architecture of most ecologically relevant traits is poorly understood. Differences in elevation can impose substantial divergent selecti ... Full text Cite

Populations Are Differentiated in Biological Rhythms without Explicit Elevational Clines in the Plant Mimulus laciniatus.

Journal Article Journal of biological rhythms · October 2020 Environmental variation along an elevational gradient can yield phenotypic differentiation resulting from varying selection pressures on plant traits related to seasonal responses. Thus, genetic clines can evolve in a suite of traits, including the circadi ... Full text Cite

Patterns of Hybrid Seed Inviability in the Mimulus guttatus sp. Complex Reveal a Potential Role of Parental Conflict in Reproductive Isolation.

Journal Article Current biology : CB · January 2020 Genomic conflicts may play a central role in the evolution of reproductive barriers. Theory predicts that early-onset hybrid inviability may stem from conflict between parents for resource allocation to offspring. Here, we describe M. decorus: a group of c ... Full text Cite

Developmental Analysis of Mimulus Seed Transcriptomes Reveals Functional Gene Expression Clusters and Four Imprinted, Endosperm-Expressed Genes.

Journal Article Frontiers in plant science · January 2020 The double fertilization of the female gametophyte initiates embryogenesis and endosperm development in seeds via the activation of genes involved in cell differentiation, organ patterning, and growth. A subset of genes expressed in endosperm exhibi ... Full text Cite

Dissecting the role of a large chromosomal inversion in life history divergence throughout the Mimulus guttatus species complex.

Journal Article Molecular ecology · March 2019 Chromosomal inversions can play an important role in adaptation, but the mechanism of their action in many natural populations remains unclear. An inversion could suppress recombination between locally beneficial alleles, thereby preventing maladaptive res ... Full text Cite

Hybrid inviability and differential submergence tolerance drive habitat segregation between two congeneric monkeyflowers.

Journal Article Ecology · December 2018 Closely related, ecologically similar species are often separated at small geographic scales while being broadly sympatric. Both adaptation to abiotic environmental conditions and a variety of biotic interactions may determine small-scale allopatry. In Nor ... Full text Cite

Major QTL controls adaptation to serpentine soils in Mimulus guttatus.

Journal Article Molecular ecology · December 2018 Spatially varying selection is a critical driver of adaptive differentiation. Yet, there are few examples where the fitness effects of naturally segregating variants that contribute to local adaptation have been measured in the field. Plant adaptation to h ... Full text Cite

Selective trade-offs maintain alleles underpinning complex trait variation in plants.

Journal Article Science (New York, N.Y.) · August 2018 To understand evolutionary factors that maintain complex trait variation, we sequenced genomes from a single population of the plant Mimulus guttatus, identifying hundreds of nucleotide variants associated with morphological and life history traits. ... Full text Cite

Dramatic evolution of body length due to postembryonic changes in cell size in a newly discovered close relative of Caenorhabditis elegans

Journal Article Evolution Letters · August 1, 2018 Understanding morphological diversity—and morphological constraint—has been a central question in evolutionary biology since its inception. Nematodes of the genus Caenorhabditis, which contains the well-studied model organism C. elegans, display remarkable ... Full text Cite

Differential adaptation to a harsh granite outcrop habitat between sympatric Mimulus species.

Journal Article Evolution; international journal of organic evolution · June 2018 Understanding which environmental variables and traits underlie adaptation to harsh environments is difficult because many traits evolve simultaneously as populations or species diverge. Here, we investigate the ecological variables and traits that underli ... Full text Cite

Plastic breeding system response to day length in the California wildflower Mimulus douglasii.

Journal Article American journal of botany · April 2018 Premise of the studyAngiosperms have evolved multiple breeding systems that allow reproductive success under varied conditions. Striking among these are cleistogamous breeding systems, where individuals can produce alternative flower types special ... Full text Cite

Population-genomic inference of the strength and timing of selection against gene flow.

Journal Article Proceedings of the National Academy of Sciences of the United States of America · July 2017 The interplay of divergent selection and gene flow is key to understanding how populations adapt to local environments and how new species form. Here, we use DNA polymorphism data and genome-wide variation in recombination rate to jointly infer the strengt ... Full text Cite

Geographic Variation of Plant Circadian Clock Function in Natural and Agricultural Settings.

Journal Article Journal of biological rhythms · February 2017 The increasing demand for improved agricultural production will require more efficient breeding for traits that maintain yield under heterogeneous environments. The internal circadian oscillator is essential for perceiving and coordinating environmental cu ... Full text Cite

The genetic architecture of local adaptation and reproductive isolation in sympatry within the Mimulus guttatus species complex.

Journal Article Molecular ecology · January 2017 The genetic architecture of local adaptation has been of central interest to evolutionary biologists since the modern synthesis. In addition to classic theory on the effect size of adaptive mutations by Fisher, Kimura and Orr, recent theory addresses the g ... Full text Cite

Population structure and local selection yield high genomic variation in Mimulus guttatus.

Journal Article Molecular ecology · January 2017 Across western North America, Mimulus guttatus exists as many local populations adapted to site-specific environmental challenges. Gene flow between locally adapted populations will affect genetic diversity both within demes and across the larger metapopul ... Full text Cite

Disruption of endosperm development is a major cause of hybrid seed inviability between Mimulus guttatus and Mimulus nudatus.

Journal Article The New phytologist · May 2016 Divergence of developmental mechanisms within populations could lead to hybrid developmental failure, and might be a factor driving speciation in angiosperms. We investigate patterns of endosperm and embryo development in Mimulus guttatus and the closely r ... Full text Cite

A Segregating Inversion Generates Fitness Variation in Yellow Monkeyflower (Mimulus guttatus).

Journal Article Genetics · April 2016 Polymorphic chromosomal rearrangements can bind hundreds of genes into single genetic loci with diverse effects. Rearrangements are often associated with local adaptation and speciation and may also be an important component of genetic variation within pop ... Full text Cite

Leaf shape evolution has a similar genetic architecture in three edaphic specialists within the Mimulus guttatus species complex.

Journal Article Annals of botany · August 2015 Background and aimsThe genetic basis of leaf shape has long interested botanists because leaf shape varies extensively across the plant kingdom and this variation is probably adaptive. However, knowledge of the genetic architecture of leaf shape v ... Full text Cite

The extent and genetic basis of phenotypic divergence in life history traits in Mimulus guttatus.

Journal Article Molecular ecology · January 2015 Differential natural selection acting on populations in contrasting environments often results in adaptive divergence in multivariate phenotypes. Multivariate trait divergence across populations could be caused by selection on pleiotropic alleles or throug ... Full text Cite

Speciation on a local geographic scale: the evolution of a rare rock outcrop specialist in Mimulus.

Journal Article Philosophical transactions of the Royal Society of London. Series B, Biological sciences · August 2014 Speciation can occur on both large and small geographical scales. In plants, local speciation, where small populations split off from a large-ranged progenitor species, is thought to be the dominant mode, yet there are still few examples to verify speciati ... Full text Cite

Divergent population structure and climate associations of a chromosomal inversion polymorphism across the Mimulus guttatus species complex.

Journal Article Molecular ecology · June 2014 Chromosomal rearrangement polymorphisms are common and increasingly found to be associated with adaptive ecological divergence and speciation. Rearrangements, such as inversions, reduce recombination in heterozygous individuals and thus can protect favoura ... Full text Cite

Comparative linkage maps suggest that fission, not polyploidy, underlies near-doubling of chromosome number within monkeyflowers (Mimulus; Phrymaceae).

Journal Article Heredity · May 2014 Changes in chromosome number and structure are important contributors to adaptation, speciation and macroevolution. In flowering plants, polyploidy and subsequent reductions in chromosome number by fusion are major sources of chromosomal evolution, but chr ... Full text Cite

The standing pool of genomic structural variation in a natural population of Mimulus guttatus.

Journal Article Genome biology and evolution · January 2014 Major unresolved questions in evolutionary genetics include determining the contributions of different mutational sources to the total pool of genetic variation in a species, and understanding how these different forms of genetic variation interact with na ... Full text Cite

Fine-scale variation in meiotic recombination in Mimulus inferred from population shotgun sequencing.

Journal Article Proceedings of the National Academy of Sciences of the United States of America · November 2013 Meiotic recombination rates can vary widely across genomes, with hotspots of intense activity interspersed among cold regions. In yeast, hotspots tend to occur in promoter regions of genes, whereas in humans and mice, hotspots are largely defined by bindin ... Full text Cite

Allotetraploid Mimulus sookensis are highly interfertile despite independent origins.

Journal Article Molecular ecology · November 2012 Polyploidy (whole-genome duplication) has contributed significantly to angiosperm evolution and diversification. To date, it has been found that most polyploids are the result of multiple formation events, which may contribute to genetic diversity and affe ... Full text Cite

Spatially and temporally varying selection on intrapopulation quantitative trait loci for a life history trade-off in Mimulus guttatus.

Journal Article Molecular ecology · August 2012 Why do populations remain genetically variable despite strong continuous natural selection? Mutation reconstitutes variation eliminated by selection and genetic drift, but theoretical and experimental studies each suggest that mutation-selection balance in ... Full text Cite

What can patterns of differentiation across plant genomes tell us about adaptation and speciation?

Journal Article Philosophical Transactions of the Royal Society B · 2012 Cite

Five anthocyanin polymorphisms are associated with an R2R3-MYB cluster in Mimulus guttatus (Phrymaceae).

Journal Article American journal of botany · January 2012 Premise of studyBotanists have long been interested in the reasons for genetic variation among individuals, populations, and species of plants. The anthocyanin pathway is ideal for studying the evolution of such phenotypic variation.Methods Full text Cite

Genetic evidence for hybridization in red oaks (Quercus sect. Lobatae, Fagaceae).

Journal Article American journal of botany · January 2012 Premise of the studyHybridization is pervasive in many plant taxa, with consequences for species taxonomy, local adaptation, and management. Oaks (Quercus spp.) are thought to hybridize readily yet retain distinct traits, drawing into question the ... Full text Cite

Mapping of ionomic traits in Mimulus guttatus reveals Mo and Cd QTLs that colocalize with MOT1 homologues.

Journal Article PloS one · January 2012 Natural variation in the regulation of the accumulation of mineral nutrients and trace elements in plant tissues is crucial to plant metabolism, development, and survival across different habitats. Studies of the genetic basis of natural variation in nutri ... Full text Cite

Evidence against equimolarity of large repeat arrangements and a predominant master circle structure of the mitochondrial genome from a monkeyflower (Mimulus guttatus) lineage with cryptic CMS.

Journal Article Genome biology and evolution · January 2012 Despite intense investigation for over 25 years, the in vivo structure of plant mitochondrial genomes remains uncertain. Mapping studies and genome sequencing generally produce large circular chromosomes, whereas electrophoretic and microscopic studies typ ... Full text Cite

Explaining the heritability of an ecologically significant trait in terms of individual quantitative trait loci.

Journal Article Biology letters · December 2011 Most natural populations display substantial genetic variation in behaviour, morphology, physiology, life history and the susceptibility to disease. A major challenge is to determine the contributions of individual loci to variation in complex traits. Quan ... Full text Cite

The statistics of bulk segregant analysis using next generation sequencing.

Journal Article PLoS Comput Biol · November 2011 We describe a statistical framework for QTL mapping using bulk segregant analysis (BSA) based on high throughput, short-read sequencing. Our proposed approach is based on a smoothed version of the standard G statistic, and takes into account variation in a ... Full text Link to item Cite

Evolutionary genetics of plant adaptation.

Journal Article Trends in genetics : TIG · July 2011 Plants provide unique opportunities to study the mechanistic basis and evolutionary processes of adaptation to diverse environmental conditions. Complementary laboratory and field experiments are important for testing hypotheses reflecting long-term ecolog ... Full text Cite

Gene duplication in Mimulus underlies parallel floral evolution via independent trans-regulatory changes.

Journal Article Current biology : CB · April 2011 Identifying the genetic basis of parallelism reveals the means by which evolution repeats itself and shows what aspects-if any-may be predictable. The recently tetraploid luteus group of Mimulus contains five species native to central Chile, three of which ... Full text Cite

The ecology and genetics of Mimulus

Journal Article Annual Review of Ecology, Evolution, and Systematics · January 1, 2011 Full text Cite

A widespread chromosomal inversion polymorphism contributes to a major life-history transition, local adaptation, and reproductive isolation.

Journal Article PLoS biology · September 2010 The role of chromosomal inversions in adaptation and speciation is controversial. Historically, inversions were thought to contribute to these processes either by directly causing hybrid sterility or by facilitating the maintenance of co-adapted gene compl ... Full text Open Access Cite

Geographical variation in postzygotic isolation and its genetic basis within and between two Mimulus species.

Journal Article Philosophical transactions of the Royal Society of London. Series B, Biological sciences · August 2010 The aim of this study is to investigate the evolution of intrinsic postzygotic isolation within and between populations of Mimulus guttatus and Mimulus nasutus. We made 17 intraspecific and interspecific crosses, across a wide geographical scale. We examin ... Full text Cite

Is local adaptation in Mimulus guttatus caused by trade-offs at individual loci?

Journal Article Molecular ecology · July 2010 Local adaptation is considered to be the result of fitness trade-offs for particular phenotypes across different habitats. However, it is unclear whether such phenotypic trade-offs exist at the level of individual genetic loci. Local adaptation could arise ... Full text Cite

Natural variation for drought-response traits in the Mimulus guttatus species complex.

Journal Article Oecologia · January 2010 Soil moisture is a key factor affecting plant abundance and distribution, both across and within species. In response to water limitation, plants have evolved numerous morphological, physiological, and phenological adaptations. In both well-watered and wat ... Full text Cite

The genetics of inbreeding depression.

Journal Article Nature reviews. Genetics · November 2009 Inbreeding depression - the reduced survival and fertility of offspring of related individuals - occurs in wild animal and plant populations as well as in humans, indicating that genetic variation in fitness traits exists in natural populations. Inbreeding ... Full text Cite

Contribution of chromosomal polymorphisms to the G-matrix of Mimulus guttatus.

Journal Article The New phytologist · August 2009 Evolution of genetic (co)variances (the G-matrix) fundamentally influences multitrait divergence. Here, we isolated the contribution of two chromosomal quantitative trait loci (QTLs), a meiotic drive locus and a polymorphic inversion, to the overall G-matr ... Full text Cite

Genetic and physiological basis of adaptive salt tolerance divergence between coastal and inland Mimulus guttatus.

Journal Article The New phytologist · August 2009 Local adaptation is a well-established phenomenon whereby habitat-mediated natural selection drives the differentiation of populations. However, little is known about how specific traits and loci combine to cause local adaptation. Here, we conducted a set ... Full text Cite

Genetic divergence causes parallel evolution of flower color in Chilean Mimulus.

Journal Article The New phytologist · August 2009 Deciphering the genetic architecture of phenotypic change provides a framework for understanding how evolution proceeds at a genetic level, and paves the way for work at the molecular level. A series of intra- and interspecific crosses were used to investi ... Full text Cite

Origin of species in overdrive

Journal Article Science · 2009 Cite

Genetics. Origin of species in overdrive.

Journal Article Science (New York, N.Y.) · January 2009 Full text Cite

Review. The strength and genetic basis of reproductive isolating barriers in flowering plants.

Journal Article Philosophical transactions of the Royal Society of London. Series B, Biological sciences · September 2008 Speciation is characterized by the evolution of reproductive isolation between two groups of organisms. Understanding the process of speciation requires the quantification of barriers to reproductive isolation, dissection of the genetic mechanisms that con ... Cite

Ecological reproductive isolation of coast and inland races of Mimulus guttatus.

Journal Article Evolution; international journal of organic evolution · September 2008 Adaptive divergence due to habitat differences is thought to play a major role in formation of new species. However it is rarely clear the extent to which individual reproductive isolating barriers related to habitat differentiation contribute to total iso ... Full text Cite

The genetic basis of developmental abnormalities in interpopulation hybrids of the moss Ceratodon purpureus.

Journal Article Genetics · July 2008 Divergent populations are intrinsically reproductively isolated when hybrids between them either fail to develop properly or do not produce viable offspring. Intrinsic isolation may result from Dobzhansky-Muller (DM) incompatibilities, in which deleterious ... Full text Cite

Hybrid male sterility in Mimulus (Phrymaceae) is associated with a geographically restricted mitochondrial rearrangement.

Journal Article Evolution; international journal of organic evolution · May 2008 Cytoplasmic male sterility (CMS) and nuclear fertility restoration (Rf) involves intergenomic coevolution. Although male-sterile phenotypes are rarely expressed in natural populations of angiosperms, CMS genes are thought to be common. The evolutionary dyn ... Full text Cite

Is floral diversification associated with pollinator divergence? Flower shape, flower colour and pollinator preference in Chilean Mimulus.

Journal Article Annals of botany · April 2008 Background and aimsAdaptation to different pollinators is thought to drive divergence in flower colour and morphology, and may lead to interspecific reproductive isolation. Floral diversity was tested for association with divergent pollinator pref ... Full text Cite

Patterns of nucleotide variation and reproductive isolation between a Mimulus allotetraploid and its progenitor species.

Journal Article Molecular ecology · April 2008 Here we report our characterization of a widespread, highly selfing Mimulus allotetraploid formed by interspecific hybridization between M. nasutus and M. guttatus. Nucleotide variation at two nuclear loci (mCYCA and mAP3) within and among tetraploid popul ... Full text Cite

Pollen limitation and natural selection on floral characters in the yellow monkeyflower, Mimulus guttatus.

Journal Article The New phytologist · January 2008 In flowering plants, pollen limitation has been proposed to intensify selection on floral characters important in pollinator attraction, but may also select for traits that increase seed set through autonomous selfing. Here, a factorial design (+/- pollen ... Full text Cite

Which evolutionary processes influence natural genetic variation for phenotypic traits?

Journal Article Nature reviews. Genetics · November 2007 Although many studies provide examples of evolutionary processes such as adaptive evolution, balancing selection, deleterious variation and genetic drift, the relative importance of these selective and stochastic processes for phenotypic variation within a ... Full text Cite

Plant speciation.

Journal Article Science (New York, N.Y.) · August 2007 Like the formation of animal species, plant speciation is characterized by the evolution of barriers to genetic exchange between previously interbreeding populations. Prezygotic barriers, which impede mating or fertilization between species, typically cont ... Full text Cite

A linkage map reveals a complex basis for segregation distortion in an interpopulation cross in the moss Ceratodon purpureus.

Journal Article Genetics · August 2007 We report the construction of a linkage map for the moss Ceratodon purpureus (n = 13), based on a cross between geographically distant populations, and provide the first experimental confirmation of maternal chloroplast inheritance in bryophytes. From a ma ... Full text Cite

Ecological divergence associated with mating system causes nearly complete reproductive isolation between sympatric Mimulus species.

Journal Article Evolution; international journal of organic evolution · January 2007 Speciation often involves the evolution of numerous prezygotic and postzygotic isolating barriers between divergent populations. Detailed knowledge of the strength and nature of those barriers provides insight into ecological and genetic factors that direc ... Full text Cite

Natural variation for a hybrid incompatibility between two species of Mimulus.

Journal Article Evolution; international journal of organic evolution · January 2007 Understanding the process by which hybrid incompatibility alleles become established in natural populations remains a major challenge to evolutionary biology. Previously, we discovered a two-locus Dobzhansky-Muller incompatibility that causes severe hybrid ... Full text Cite

Divergent selection on flowering time contributes to local adaptation in Mimulus guttatus populations.

Journal Article Evolution; international journal of organic evolution · December 2006 The timing of when to initiate reproduction is an important transition in any organism's life cycle. There is much variation in flowering time among populations, but we do not know to what degree this variation contributes to local adaptation. Here we use ... Full text Cite

Relaxed selection among duplicate floral regulatory genes in Lamiales.

Journal Article Journal of molecular evolution · October 2006 Polyploidization is a prevalent mode of genome diversification within plants. Most gene duplicates arising from polyploidization (paralogs) are typically lost, although a subset may be maintained under selection due to dosage, partitioning of gene function ... Full text Cite

A cytonuclear incompatibility causes anther sterility in Mimulus hybrids.

Journal Article Evolution; international journal of organic evolution · July 2006 Multilocus interactions (also known as Dobzhansky-Muller incompatibilities) are thought to be the major source of hybrid inviability and sterility. Because cytoplasmic and nuclear genomes have conflicting evolutionary interests and are often highly coevolv ... Full text Cite

A simple genetic incompatibility causes hybrid male sterility in mimulus.

Journal Article Genetics · April 2006 Much evidence has shown that postzygotic reproductive isolation (hybrid inviability or sterility) evolves by the accumulation of interlocus incompatibilities between diverging populations. Although in theory only a single pair of incompatible loci is neede ... Full text Cite

Pleiotropic quantitative trait loci contribute to population divergence in traits associated with life-history variation in Mimulus guttatus.

Journal Article Genetics · March 2006 Evolutionary biologists seek to understand the genetic basis for multivariate phenotypic divergence. We constructed an F2 mapping population (N = 539) between two distinct populations of Mimulus guttatus. We measured 20 floral, vegetative, and life-history ... Full text Cite

Duplication of floral regulatory genes in the Lamiales.

Journal Article American journal of botany · August 2005 Duplication of some floral regulatory genes has occurred repeatedly in angiosperms, whereas others are thought to be single-copy in most lineages. We selected three genes that interact in a pathway regulating floral development conserved among higher trico ... Full text Cite

Transmission ratio distortion in intraspecific hybrids of Mimulus guttatus: implications for genomic divergence.

Journal Article Genetics · May 2005 We constructed a genetic linkage map between two divergent populations of Mimulus guttatus. We genotyped an F(2) mapping population (N = 539) at 154 AFLP, microsatellite, and gene-based markers. A framework map was constructed consisting of 112 marker loci ... Full text Cite

A novel meiotic drive locus almost completely distorts segregation in mimulus (monkeyflower) hybrids.

Journal Article Genetics · January 2005 We report the discovery, mapping, and characterization of a meiotic drive locus (D) exhibiting nearly 100% nonrandom transmission in hybrids between two species of yellow monkeyflowers, outcrossing Mimulus guttatus and selfing M. nasutus. Only 1% of F(2) h ... Full text Cite

Patterns of nucleotide diversity in two species of Mimulus are affected by mating system and asymmetric introgression.

Journal Article Evolution; international journal of organic evolution · November 2003 The evolutionary transition from outcrossing to self-fertilization has far-reaching implications for patterns of intraspecific genetic diversity and the potential for speciation. Using DNA sequence variation at two nuclear loci, we examined the divergence ... Full text Cite

Minor quantitative trait loci underlie floral traits associated with mating system divergence in Mimulus.

Journal Article Evolution; international journal of organic evolution · November 2002 The genetic basis of species differences provides insight into the mode and tempo of phenotypic divergence. We investigate the genetic basis of floral differences between two closely related plant taxa with highly divergent mating systems, Mimulus guttatus ... Full text Cite

A manipulative experiment to estimate biparental inbreeding in monkeyflowers

Journal Article International Journal of Plant Sciences · January 1, 2002 Biparental inbreeding occurs when plants receive pollen from genetically related neighbors. The frequency of biparental inbreeding in natural populations is unknown but directly relevant to the evolution of plant mating systems. We suggest a simple manipul ... Full text Cite

Evidence for Dobzhansky-Muller incompatibilites contributing to the sterility of hybrids between Mimulus guttatus and M. nasutus.

Journal Article Evolution; international journal of organic evolution · October 2001 Both chromosomal rearrangements and negative interactions among loci (Dobzhansky-Muller incompatibilities) have been advanced as the genetic mechanism underlying the sterility of interspecific hybrids. These alternatives invoke very different evolutionary ... Full text Cite

Deleterious mutations and genetic variation for flower size in Mimulus guttatus.

Journal Article Evolution; international journal of organic evolution · May 2001 Mimulus guttatus is a wildflower that exhibits substantial genetic variation in flower size. Here, we test the hypothesis that this variation is caused by deleterious mutations maintained through mutation-selection balance. The deleterious-mutation model p ... Full text Cite

Inbreeding load, average dominance and the mutation rate for mildly deleterious alleles in Mimulus guttatus.

Journal Article Genetics · December 1999 The goal of this study is to provide information on the genetics of inbreeding depression in a primarily outcrossing population of Mimulus guttatus. Previous studies of this population indicate that there is tremendous inbreeding depression for nearly ever ... Full text Cite

The contribution of male-sterility mutations to inbreeding depression in Mimulus guttatus.

Journal Article Heredity · September 1999 The magnitude of inbreeding depression can influence many aspects of a population's ecology and evolution, including the nature of selection acting on the mating system and the chances that the population will go extinct during periods of small population ... Full text Cite

Spontaneous deleterious mutation in Arabidopsis thaliana.

Journal Article Proceedings of the National Academy of Sciences of the United States of America · September 1999 The frequency and selective impact of deleterious mutations are fundamental parameters in evolutionary theory, yet they have not been directly measured in a plant species. To estimate these quantities, we allowed spontaneous mutations to accumulate for 10 ... Full text Cite

The role of genes of large effect on inbreeding depression in Mimulus guttatus

Journal Article Evolution · January 1, 1999 Severe inbreeding depression is routinely observed in outcrossing species. If inbreeding load is due largely to deleterious alleles of large effect, such as recessive lethals or steriles, then most of it is expected to be purged during brief periods of inb ... Full text Cite

The distribution of individual inbreeding coefficients and pairwise relatedness in a population of Mimulus guttatus

Journal Article Heredity · January 1, 1999 In order to infer population structure at the individual level, we estimated individual inbreeding coefficients and examined the relationship between geographical distance and genetic relatedness from polymorphic microsatellite data for a population of Mim ... Full text Cite

The genomic mutation rate for fitness in Arabidopsis thaliana

Journal Article Procedings of the National Academy of Science, USA · 1999 Cite

Spontaneous deleterious mutation

Journal Article Evolution · 1999 Cite

Perspective: Spontaneous deleterious mutation

Journal Article Evolution · January 1, 1999 Mildly deleterious mutation has been invoked as a leading explanation for a diverse array of observations in evolutionary genetics and molecular evolution and is thought to be a significant risk of extinction for small populations. However, much of the emp ... Full text Cite

Polymorphic microsatellite loci in Mimulus guttatus and related species

Journal Article Molecular Ecology · January 1, 1998 The evolution of self-fertilization from outcrossing is one of the most common evolutionary transitions in flowering plants. One goal of our research is to develop a linkage map based upon microsatellite loci in Mimulus guttatus and the selfing derivative ... Full text Cite

Measures of phenotypic selection are biased by partial inbreeding

Journal Article Evolution · January 1, 1996 When populations are partially inbred due to the population structure or to a mixed mating system like partial self-fertilization, some individuals will be more inbred than others. This heterogeneity among individuals in the history of inbreeding can great ... Full text Cite

Individual variation in inbreeding depression: the roles of inbreeding history and mutation.

Journal Article Genetics · November 1995 We use mutation-selection recursion models to evaluate the relative contributions of mutation and inbreeding history to variation among individuals in inbreeding depression and the ability of experiments to detect associations between individual inbreeding ... Full text Cite

Linearity Versus nonlinearity of offspring-parent regression: an experimental study of Drosophila melanogaster.

Journal Article Genetics · October 1994 An experiment was conducted to investigate the offspring-parent regression for three quantitative traits (weight, abdominal bristles and wing length) in Drosophila melanogaster. Linear and polynomial models were fitted for the regressions of a character in ... Full text Cite

Effects of different levels of inbreeding on fitness components in Mimulus guttatus

Journal Article Evolution · January 1, 1993 Determined whether synergism exists for genes affecting fitness components in two partially selfing populations of monkey flower. For each wild population, a large randomly mated base population was constructed and many independent lines, inbred to differi ... Full text Cite

Partial self-fertilization and inbreeding depression in two populations of mimulus guttatus

Journal Article Heredity · January 1, 1993 Inbreeding depression is likely to be a common selective force opposing the automatic selective advantage of self-fertilization in self-compatible plants and animals, yet relatively few studies have measured both the breeding system and inbreeding depressi ... Full text Cite

Variance in search time: Do groups always reduce risk?

Journal Article Animal Behaviour · January 1, 1986 Full text Cite