The following sections of this BookRags Literature Study Guide is offprint from Gale's For Students Series: Presenting Analysis, Context, and Criticism on Commonly Studied Works: Introduction, Author Biography, Plot Summary, Characters, Themes, Style, Historical Context, Critical Overview, Criticism and Critical Essays, Media Adaptations, Topics for Further Study, Compare & Contrast, What Do I Read Next?, For Further Study, and Sources.
(c)1998-2002; (c)2002 by Gale. Gale is an imprint of The Gale Group, Inc., a division of Thomson Learning, Inc. Gale and Design and Thomson Learning are trademarks used herein under license.
The following sections, if they exist, are offprint from Beacham's Encyclopedia of Popular Fiction: "Social Concerns", "Thematic Overview", "Techniques", "Literary Precedents", "Key Questions", "Related Titles", "Adaptations", "Related Web Sites". (c)1994-2005, by Walton Beacham.
The following sections, if they exist, are offprint from Beacham's Guide to Literature for Young Adults: "About the Author", "Overview", "Setting", "Literary Qualities", "Social Sensitivity", "Topics for Discussion", "Ideas for Reports and Papers". (c)1994-2005, by Walton Beacham.
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A hybrid is the offspring of a mating between two genetically dissimilar parents. This often occurs between two related species or varieties. When hybridization is attempted between two unrelated species, the genetic incompatibility is usually too great and the embryo fails to thrive or fertilization does not occur.
Oftentimes, hybrids are sterile, resulting from the failure of the chromosomes to pair up properly during meiosis. The more distantly related the organisms the more likely it is that the offspring will be sterile. Sterile plants are bred using vegetative means of propagation, while sterile animal hybrids must always be bred from the parental types.
Perhaps the most famous hybrid is the cross between a horse and a donkey: the mule. The mule is sterile because the horse has a diploid chromosome number of 62 and the donkey has a diploid chromosome number of 64. Subsequently, the hybrid mule has a diploid number of 63 chromosomes, which are unable to pair correctly during meiosis. The mule is a cross between a female horse and a male donkey. The cross between a male horse and a female donkey is a hinny.