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Hermaphroditism: A Primer on the Biology, Ecology, and Evolution of Dual Sexuality

Copyright Date: 2011
Pages: 256
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  • Book Info
    Book Description:

    While it is true that members of most sexually reproducing species can be defined as either male or female, those who belong to the rest of the biological world are not so simply understood. Hermaphroditic creatures reproduce both as male and as female individuals, providing a fascinating glimpse into alternative sexual practices in nature and their ecological and evolutionary successes and failures.

    Eloquently written by an award-winning biologist and pioneer in molecular ecology, this primer on hermaphroditism traces the phenomenon throughout Earth's myriad species, accounting for the adaptive significance of alternative sexual systems. Accessible and richly illustrated, the text maps the evolutionary origins of hermaphroditism, as well as its historical instances and fictional representations, underscoring the relevance of dual sexuality to our biological, intellectual, and cultural making. 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 compelling revelations, this textbook stands alone in its clear yet comprehensive treatment of hermaphroditism and its unique challenge to the supremacy of separate sexes.

    eISBN: 978-0-231-52715-6
    Subjects: Biological Sciences, Ecology & Evolutionary Biology, Botany & Plant Sciences

Table of Contents

  1. Front Matter
    (pp. i-vi)
  2. Table of Contents
    (pp. vii-x)
    (pp. xi-xviii)
  4. CHAPTER ONE Two Sexes in One
    (pp. 1-42)

    A hermaphrodite is an individual that produces functional male gametes and female gametes (sex cells) during its lifetime. This capacity to reproduce both as male and female has many biological ramifications. It raises, for example, the issue of what defines a male versus a female in any species, which in turn motivates the question of what constitutes a male gamete versus a female gamete. With respect to ontogeny (individual development), hermaphroditism begs questions about the genetic and environmental determinants as well as the proximate hormonal and physiological underpinnings of dual sexuality. With respect to ethology (behavior), hermaphroditism raises questions about...

  5. CHAPTER TWO Dual-sex Plants
    (pp. 43-80)

    Hermaphroditism in plants is a vast subject. This chapter and the next will highlight dual-sex phenomena in plants and invertebrate animals, respectively, and thereby introduce reproductive topics that these organisms have motivated in the scientific literature. My goals are to profile dual-sex plants and invertebrates in nature as fascinating creatures in their own right, provide a biological overview of various reproductive modalities in these organisms, and thereby also add empirical and conceptual backdrop for discussions of hermaphroditic vertebrates in chapter 4.

    Botanists have long known that most species of angiosperms (flowering plants with fruit-encased seeds) include dual-sex individuals. For example,...

  6. CHAPTER THREE Dual-sex Invertebrates
    (pp. 81-128)

    An estimated 65,000 species (approximately 6%) of known invertebrate animals are hermaphroditic (Jarne and Auld 2006). If we exclude the species rich insects (none of which appears to be hermaphroditic), the incidence of hermaphroditism in the remaining invertebrate species rises to about 30%. Hermaphroditism is also taxonomically widespread, occurring in 22 of the 32 invertebrate phyla (69%) and being ubiquitous in 12 of them (table 3.1). At the next lower taxonomic level, hermaphroditism is represented in nearly 50% of 85 invertebrate classes (Eppley and Jesson 2008). Hermaphroditism is also common in fungi (which are related more closely to animals than...

  7. CHAPTER FOUR Dual-sex Vertebrates
    (pp. 129-170)

    In vertebrate animals, true hermaphroditism (discussed further below) essentially is confined to fishes. This chapter will highlight piscine examples of operational hermaphroditism in both of its two primary reproductive forms: sequential (or serial) and simultaneous. Many of the conceptual and empirical topics that arose in discussions of hermaphroditic plants (chapter 2) and invertebrate animals (chapter 3) will again be germane to considerations of vertebrate species composed of dual-sex individuals.

    The hermaphroditic condition has been described within more than 250 (ca. 1%) of the world’s 25,000 extant species of teleosts or bony fishes (Pauly 2004). The phenomenon is represented by at...

    (pp. 171-184)
    (pp. 185-226)
  10. INDEX
    (pp. 227-232)