Gender and Sexual Dimorphism in Flowering Plants

1 Gender and Sexual Dimorphism in Flowering Plants: A Review of Terminology, Biogeographic patterns, Ecological Correlates, and Phylogenetic Approaches.- 1.1 Introduction.- 1.2 Terminology.- 1.3 Incidence of Dioecy.- 1.3.1 Overview.- 1.3.2 Ecological Associations.- 1.3.3 Geographic Patterns.- 1.4 Importance of Phylogenetic Approaches.- 1.5 Using Phylogenies to Understand Process and Pattern.- 1.5.1 Phylogenetic Distributions.- 1.5.2 Self-Incompatibility and Dioecy.- 1.5.3 Dioecy and Fleshy Fruits.- 1.5.4 Habitat Shifts, Pollination Biology, and Changes in Outcrossing Rates.- 1.6 Conclusions.- References.- 2 Theories of the Evolution of Dioecy.- 2.1 Introduction.- 2.2 Importance of Theoretical Models.- 2.3 Pathways to Dioecy.- 2.4 Theoretical Relationships Between Allocation of Reproductive Resources and Invasion of Populations by New Sex Morphs.- 2.4.1 Fitness in Outcrossing and Partially Selfing Cosexes and Allocation in Cosexes.- 2.4.2 Invasion of Populations by Females and Males.- 2.4.3 Effect of Cosex Allocations on Invasion by Unisexuals or Partially Sterile Types.- 2.4.4 Effects of Unisexuals on Cosex Allocations.- 2.4.5 Other Possible Routes to Dioecy.- 2.5 Testing the Theory.- 2.5.1 Comparative Tests.- 2.5.2 Gain Curves.- 2.5.3 Intraspecific Data.- 2.5.4 Genetic Data.- 2.6 Conclusions.- 2.7 References.- 3 Empirical Studies: Evolution and Maintenance of Dimorphic Breeding Systems.- 3.1 Introduction.- 3.2 Evolutionary Pathways to Gender Dimorphism.- 3.2.1 Approaches to the Study of Gender.- 3.2.1.1 Quantitative Description of Plant Gender.- 3.2.1.2 Theoretical Modelling.- 3.2.1.3 Phylogenetic Analysis.- 3.2.2 Overview of Pathways.- 3.2.3 From Cosexuality Via Gynodioecy to Dioecy.- 3.2.4 From Monoecy Via Paradioecy to Dioecy.- 3.2.5 From Cosexuality Via Androdioecy to Dioecy.- 3.2.6 From Heterostyly to Dioecy.- 3.2.7 From Duodichogamy or Heterodichogamy to Dioecy.- 3.2.8 The Evolution of Trioecy.- 3.3 Maintenance of Gender Dimorphism in Natural Populations.- 3.3.1 Sex Ratios.- 3.3.2 Evidence for an Outcrossing Advantage: Rates of Selfing and Levels of Inbreeding Depression.- 3.3.3 Relative Seed Fecundity of the Two Sexes.- 3.3.4 Relative Pollen Fecundity of the Two Sexes.- 3.3.5 Case Studies: Tests of Theoretical Models.- 3.3.5.1 Female Frequency and Habitat in Plantago lanceolata.- 3.3.5.2 Plant Vigour, Fruit Production and the Sex Ratio in Hebe strictissima.- 3.3.5.3 Rates of Selfing, Inbreeding Depression and the Sex Ratio.- 3.3.5.4 The Breakdown of Outcrossing Mechanism in Aralia.- 3.4 Directions for Future Research.- 3.4.1 Testable Predictions from Ecological Correlations.- 3.4.2 Other Research Gaps.- 3.5 Conclusions.- References.- 4 Theories of the Evolution of Sexual Dimorphism.- 4.1 Introduction.- 4.2 Models of Sexual Dimorphism.- 4.2.1 Types of Models.- 4.2.2 General Features.- 4.2.3 Sexual Dimorphism in a Dioecious Organism.- 4.2.3.1 Genetic Models.- 4.2.3.2 ESS Models.- 4.2.4 The Evolution of Gender and Sexual Dimorphism.- 4.2.4.1 ESS Models.- 4.2.4.2 Genetic Models.- 4.3 The Biology of Sexual Dimorphism.- 4.3.1 Disruptive Selection on Homologous Characters.- 4.3.1.1 Biological Circumstances.- 4.3.1.2 Theory on Disruptive Selection in Dioecious Organisms.- 4.3.1.3 Theory on the Evolution of Gender and Sexual Dimorphism.- 4.3.1.4 Disruptive Selection and Sexual Dimorphism in Plants.- 4.3.2 Ecological Competition.- 4.3.2.1 Biological Circumstances.- 4.3.2.2 Theory on Character Displacement Due to Intraspecific Competition.- 4.3.2.3 Competitive Character Displacement and SSS in Dioecious Plants.- 4.3.3 Intersexual Selection.- 4.3.3.1 Biological Circumstances.- 4.3.3.2 Theory on Intersexual Selection.- 4.3.3.3 Mate Choice and Sexual Dimorphism in Plants.- 4.4 Conclusions.- References.- 5 Sexual Dimorphism in Flowers and Inflorescences.- 5.1 Introduction.- 5.2 Patterns.- 5.2.1 Perianth Size.- 5.2.2 Perianth Shape.- 5.2.3 Nectar.- 5.2.4 Vestigial Characters.- 5.2.5 Other Flower Characters.- 5.2.6 Multi-Flower Characters.- 5.2.7 Questions.- 5.3 Evolutionary Hypotheses.- 5.3.1 Sexual Selection and Character Exaggeration.- 5.3.2 Specific Tests, Hypotheses, and Uncertainties.- 5.3.2.1 Perianth Size.- 5.3.2.2 Perianth Shape.- 5.3.2.3 Nectar.- 5.3.2.4 Vestigial Character.- 5.3.2.5 Other Flower Characters: Longevity.- 5.3.2.6 Multi-Flower Characters.- 5.4 Conclusions.- 5.4.1 Towards Quantitative Understanding.- 5.4.2 Size-Number Trade-Offs.- 5.4.3 Costs of Exaggeration.- 5.4.4 Variation in Costs and Benefits.- 5.4.5 Macro evolution.- References.- 6 Sexual Dimorphism in Live History.- 6.1 Introduction.- 6.2 Predictions Based on Sex-Differential Reproductive Investment.- 6.3 Patterns of Sexual Dimorphism in Life-History Traits.- 6.3.1 Response to Stress.- 6.3.2 Case Studies of Two Species in which the Cost of Reproduction Is Higher for Females.- 6.4 Factors Offsetting Between-Sex Differences in the Cost of Reproduction.- 6.4.1 Sexual Dimorphism in the Timing of Investment in Reproduction Versus Growth Within a Season.- 6.4.2 Sexual Dimorphism in the Timing of Flowering Within a Season.- 6.4.3 Sexual Dimorphism in the Frequency of Flowering.- 6.4.4 Sexual Dimorphism in Age of Maturation.- 6.4.5 Sexual Dimorphism in Physiological Traits.- 6.4.6 Sex-Differential Herbivory.- 6.5 The Contrary Case of Silene latifolia.- 6.6 Conclusions.- References.- 7 Dimorphism in Physiology and Morphology.- 7.1 Introduction.- 7.1.1 Causes of Sexual Dimorphism in Physiology and Vegetative Morphology.- 7.1.2 Physiological and Morphological Responses to Natural Selection.- 7.1.3 Physiological and Morphological Responses to Sexual Selection.- 7.1.4 Functional Significance of Dimorphism in Physiology and Morphology.- 7.2 History of Studies on Sexual Dimorphism in Plants.- 7.3 Sexual Dimorphism in Plant Form and Function in Species with SSS.- 7.3.1 Salix (Willow; Salicaceae).- 7.3.2 Acer negundo (Boxelder; Aceraceae).- 7.3.3 Simmondsia chinensis (Jojoba/Goat Nut; Buxaceae).- 7.3.4 Phoradendron juniperinum (Mistletoe; Viscaceae).- 7.3.5 Other Species.- 7.4 Sexual Dimorphism in Plant Form and Function in Species Without SSS.- 7.4.1 Silene latifolia (White Campion; Caryophyllaceae).- 7.4.2 Leucadendron (Proteaceae).- 7.4.3 Other Species.- 7.4.3.1 Agricultural and Weedy Species.- 7.4.3.2 Populus (Aspen; Salicaceae).- 7.5 Conclusions and Future Directions.- References.- 8 Sexual Dimorphism and Biotic Interactions.- 8.1 Introduction.- 8.1.1 Reproductive Allocation and Biotic Interactions.- 8.2 Sexual Differences in Competitive Ability.- 8.3 Sexual Differences in Herbivory.- 8.3.1 Herbivore Preference.- 8.3.2 Correlates of Sexual Differences in Herbivore Damage.- 8.3.3 Herbivore Performance on Male and Female Hosts.- 8.3.4 Sexual Differences in Response to Herbivory.- 8.4 Sexual Differences in Parasitism.- 8.4.1 Foliar Pathogens.- 8.4.2 Flower-Infecting Pathogens.- 8.4.3 Nonfungal Parasites.- 8.5 General Discussion.- 8.5.1 Biotic Interactions and Biased Sex Ratios.- 8.5.2 Evolution of Sexual Differences in Herbivory.- 8.5.3 Future Studies.- References.- 9 Genetics of Gender Dimorphism in Higher Plants.- 9.1 Introduction.- 9.2 Monoecious Plants.- 9.2.1 Gender Dimorphism in Cucumber.- 9.2.2 Molecular Biology of Gender Dimorphism in Maize.- 9.2.2.1 Tasselseed2.- 9.2.2.2 Gibberellin and gender dimorphism in maize.- 9.2.2.3 The Anther ear1 gene.- 9.3 Multigenic gender determination systems in dioecious plants.- 9.3.1 Mercurialis annua.- 9.3.2 A single gender determination locus.- 9.3.3 Sex chromosomes.- 9.3.3.1 Morphologically distinct sex chromosomes.- 9.3.3.2 Structure of sex chromosomes in plants.- 9.3.3.3 X/autosome balance can regulate gender dimorphism.- 9.3.3.4 X/autosome balance in Drosophila melanogaster.- 9.3.4 Comparison of Active Y Sex Chromosomes in Plants and Animals.- 9.3.4.1 The active-Y gender determination of white campion.- 9.3.4.2 The mammalian active-Y gender determination mechanism.- 9.3.4.3 Does dosage compensation occur in white campion?.- 9.3.5 Evolution of the active-Y chromosome: Male sterility.- 9.3.5.1 Cytoplasmic male sterility.- 9.3.5.2 Suppression of carpel or pistil development.- 9.4 Expression of MADS-box genes in unisexual flowers.- 9.5 Conclusions.- References.- 10 Quantitative Genetics of Sexual Dimorphism.- 10.1 Introduction.- 10.2 Quantitative Genetic Models of Sexual Dimorphism.- 10.3 Integration of Quantitative Genetics with Sexual Selection.- 10.4 Correlated Evolution and Divergence of Male and Female Traits in Dioecious Plants.- 10.5 Correlated Evolution and Divergence of Male and Female Function in Hermaphroditic Plants.- 10.6 Conclusions.- 10.7 References.- Taxonomic Index.