Heterosis

Article By:

Lippman, Zachary B. Watson School of Biological Sciences, Cold Spring Harbor Laboratory, Cold Spring Harbor, New York.

Last reviewed:January 2020

DOI:https://doi.org/10.1036/1097-8542.316500

Hybrid vigor or increase in size, yield, and performance found in crossbred hybrids. One of the greatest unresolved mysteries in biology is why intercrossing different varieties, and sometimes species, of plants or animals frequently results in hybrid progeny with superior growth and fertility compared to their inbred parents. Charles Darwin was the first to experiment on hybrid vigor, also known as heterosis, in his pursuit to explain why sexual reproduction is so prevalent in nature. The rediscovery of heterosis by corn breeders at the turn of the twentieth century propelled this phenomenon to the forefront of genetic research because it provided a satisfying explanation for fitness variation in natural populations and, more importantly, revealed a simple method to dramatically increase crop yields. Even the superior toughness of the mule, resulting from mating a horse and a donkey, is believed to be one of many heterotic responses observed in animals. Over the past century, an expansive body of genetic and molecular data on heterosis has been produced, but often with conflicting conclusions. Only within the past few years has a consensus begun to emerge that heterosis comes in myriad forms and mechanisms depending on the organism and phenotype under investigation. See also: Breeding (animal); Breeding (plant); Genetics

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