Covering both the internal and external incubation of offspring, this book provides a biology-rich survey of the natural history, ecology, genetics, and evolution of pregnancy-like phenomena. From mammals and other live-bearing organisms to viviparous reptiles, male-pregnant fishes, larval-brooding worms, crabs, sea cucumbers, and corals, the world's various species display pregnancy and other forms of parental devotion in surprisingly multifaceted ways. An adult female (or male) can incubate its offspring in a womb, stomach, mouth, vocal sac, gill chamber, epithelial pouch, backpack, leg pocket, nest, or an encasing of embryos, and by studying these diverse examples from a comparative vantage point, the ecological and evolutionary-genetic outcomes of different reproductive models become fascinatingly clear.

John C. Avise discusses each mode of pregnancy and the decipherable genetic signatures it has left on the reproductive structures, physiologies, and innate sexual behaviors of extant species. By considering the many biological aspects of gestation from different evolutionary angles, Avise offers captivating new insights into the significance of "heavy" parental investment in progeny.

Preface
Part I: Distribution and Diversity of Pregnancy
1. One Generation Inside Another
The Sexual Lifecycle
Ontogenetic and Evolutionary Gradations of Pregnancy
Viviparous Pregnancy in the Reproductive Timeline
Heterochrony
Some Unorthodox Routes to Internal Pregnancy
Sexual Inequalities and Female Authority Over Reproduction
Other Sexual Asymmetries Related to Biological Parenthood
Evolutionary Reconstructions
Summary
2. Vertebrate Live-Bearers: The Borne and the Born
Viviparity
Evolutionary Origins
Developmental Sequences
Trophic Relationships Between Mother and Fetus
The Cast of Viviparous Vertebrates
Summary
3. Vertebrate Alternatives to Standard Pregnancy
Oviparity: The Borne and the Hatched
The Cast of Oviparous Vertebrates
Intermediate Conditions and Evolutionary Transitions
Summary
4. Nonvertebrate Brooders
The Cast of Players
Evolutionary Transitions
Conflicts Promoted by Brooding
Genetic Parentage Assessments
Summary
5. Human Pregnancy in Mythology and in Real Life
Conception and Contraception
Extracorporeal Fertilization
Superfetation
Twinning or Multibirth Pregnancy
Ectopic Pregnancy
From Preterm Labor to Prolonged Pregnancy
Spontaneous Abortion
Induced Abortion and Infanticide
Cesarean Section
Precocious Puberty
Standard Vaginal Delivery
The Placenta
Menopause
Male Pregnancy
Summary
Part II: Evolutionary Ramifications of Pregnancy
6. Natural Selection During Mammalian Pregnancy
Delayed Implantation
Polyembryony
Dizygotic Twinning
Cooperation and Conflict Within the Nuclear Family
Evolutionary Conflict in Mother-Offspring Relations
Other Categories of Conflict
Summary
7. Sexual Selection and Piscine Pregnancy
Anisogamy, Sexual Selection, and Animal Mating Behaviors
Categories of Sexual Selection
Female Pregnancy and Traditional Female Choice
Internal Male Pregnancy
External Pregnancy
Summary
8. Pregnancy in a Comparative Light
Sexual Selection and Multiple Mating by the Pregnant Gender
Natural Selection Stemming from Pregnancy and Brooding
Summary
Epilogue
Appendix: Molecular-Genetic Parentage Analyses
Glossary
References Cited
Index