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.
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Avise distills an enormous body of research into a lucid presentation of two themes. One is the remarkably diverse natural history of pregnancy, which includes oddities like male pregnancy in seahorses or mother frogs that incubate tadpoles in their stomachs, thus equating regurgitation with birth. The second is the current scientific thinking for the evolution of this diversity. Avise emphasizes that pregnancy is not the product of an adaptive, harmonious relationship between mother and offspring; it is instead shaped by conflicts between fathers, mothers, and offspring.
