Hermaphroditism

by Avise, John C.; Nicholson, Trudy

• ISBN13: 9780231153867
• ISBN10: 0231153864
• Format: Hardcover
• Copyright: 2011-03-15
• Publisher: Columbia Univ Pr

Summary

While members of most sexually reproducing species are either male or female, individuals belonging to the rest of the biological world are not so simply defined. Hermaphroditic creatures reproduce both as a male and as a female, providing a fascinating example of alternative sexual practice and its ecological and evolutionary successes. Eloquently written by an award-winning biologist and pioneer in molecular ecology, this primer traces the phenomenon of hermaphroditism throughout Earth's species and the adaptive significance of alternative sexual systems. The volume's accessible and richly illustrated text covers the evolutionary origins of hermaphroditism and its historical and fictional instances, proving the relevance of dual sexuality to the everyday world. John C. Avise describes the genetics, ecology, phylogeny, and natural history of hermaphroditic plants, fish, and invertebrate animals and details organisms that either reproduce simultaneously as male and female or switch routinely between one sex and the other. Filled with surprising creatures and inherently compelling topics, this book stands alone in its clear yet comprehensive treatment of hermaphroditism and its unique challenge to the supremacy of separate sexes.

Author Biography

John C. Avise is Distinguished Professor of Ecology and Evolutionary Biology at the University of California, Irvine. He is an elected member of both the National Academy of Sciences and the American Academy of Arts and Sciences, and the author or editor of 20 books, including most recently Inside the Human Genome: A Case for Non-intelligent Design; Molecular Ecology and Evolution: The Organisms Side; and Clonality: The Genetics, Ecology, and Evolution of Sexual Abstinence in Vertebrate Animals.

Table of Contents

Preface	p. xi
The Phenomenon of Dual Sexuality	p. xi
Hermaphroditism in Fiction	p. xii
Hermaphroditism in the Real World	p. xiv
Two Sexes in One	p. 1
Maleness and Femaleness	p. 4
Anisogamy and the Separate-sex Condition	p. 7
Evolutionary Origins	p. 8
Evolutionary Ramifications	p. 11
Sex Ratios in Separate-sex Taxa	p. 19
Relationship to Sexual Selection and Mating Systems	p. 20
Impact on Demographic Parameters	p. 26
Sex Ratios in Hermaphroditic Taxa	p. 28
Hermaphroditism Versus Separate Sexes	p. 30
Fitness Considerations	p. 30
Mating Systems and Related Phenomena	p. 32
Sex Allocation	p. 34
Phylogenetic Legacy Versus Contemporary Adaptive Significance	p. 36
Summary	p. 41
Dual-sex Plants	p. 43
Terminology	p. 44
Alternative Sexual Systems: Natural History and Examples	p. 47
Hermaphroditism	p. 47
Monoecy	p. 51
Andromonoecy	p. 51
Gynomonoecy	p. 52
Gynodioecy	p. 53
Androdioecy	p. 54
Trioecy	p. 55
Sex-changers	p. 56
Dioecy	p. 58
Cosexuality Versus Dioecy	p. 58
Ecological Considerations	p. 59
Phylogenetic Character Mapping	p. 60
Transitional States	p. 63
An Evolutionary Enigma	p. 68
Selfing Versus Outcrossing	p. 69
Inbreeding	p. 70
Coadapted Genotypes	p. 73
Fertilization Insurance	p. 75
Sex Allocation	p. 76
Sexual Selection in Plants	p. 78
Summary	p. 79
Dual-sex Invertebrates	p. 81
Biological Examples	p. 83
Reef-building Corals	p. 83
Love-dart Snails, Earthworms, and Sea Slugs	p. 83
Sperm-storing Freshwater Snails	p. 89
Sex-changing Limpets, Isopods, and Polychaetes	p. 91
Androdioecious Clam Shrimps and Gynodioecious Sea Anemones	p. 92
Protandric Simultaneously Hermaphroditic Shrimps	p. 93
Quasi-asexual Flatworms	p. 95
Other Oddities	p. 95
Sex Determination and Pseudohermaphroditism	p. 96
Evolutionary Histories: Gonochorism and Hermaphroditism	p. 97
Phylogenetic Character Mapping	p. 97
Gynodioecy and Androdioecy	p. 100
Genetics	p. 101
Selective Pressures	p. 102
Selfing Versus Outcrossing	p. 103
Genetic Considerations	p. 105
Ecological Considerations	p. 107
Joint Genetic and Ecological Considerations	p. 108
Sex Allocation in Simultaneous Hermaphrodites	p. 109
Selfing and Allocation to Female Function	p. 112
Stress and Allocation to Male Function	p. 112
Local Mate Competition	p. 113
Local Resource Competition	p. 114
Brooding Constraints	p. 115
Intra-individual Trade-offs	p. 115
Sexual Conflicts	p. 117
Other Factors	p. 120
Sex Allocation in Sequential Hermaphrodites	p. 120
The Size-advantage Hypothesis	p. 121
Mating Systems	p. 122
Conclusions About Sex Allocation Theory	p. 124
Sexual Selection	p. 124
Summary	p. 126
Dual-sex Vertebrates	p. 129
Sexual Flexibility	p. 131
Evolutionary Lability	p. 131
Ontogenetic Plasticity	p. 133
Sequential Hermaphroditism	p. 133
The Cast of Players	p. 133
Evolutionary History	p. 142
Adaptive Significance of Alternative Modes	p. 148
Simultaneous Hermaphroditism	p. 154
The Cast of Players	p. 154
Evolutionary Constraints	p. 155
Mating Behaviors in Outcrossers	p. 156
Self-fertilization	p. 161
History of Genetic Research on the Mangrove Rivulus	p. 163
Adaptive Significance of Selfing	p. 165
Summary	p. 169
Glossary	p. 171
References Cited	p. 185
Index	p. 227
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