On the Origins of New Forms of Life

2: On Hybridization


For he who is acquainted with the paths of nature, will more readily observe her deviations; and vice versa, he who has learnt her deviations, will be able more accurately to describe her paths.
—Francis Bacon, Novum Organum

(Continued from the previous page)

The reader may recall the definition of hybrid (from the Introduction): if two populations are consistently distinct with respect to one or more characters, and if a descendant of matings between those populations is discernibly mixed with respect to those characters, then that individual is a hybrid, and any process producing such individuals is hybridization. Hybrids produced by an initial cross between two parental types are known as F₁ hybrids (or the F₁ generation). Hybrids produced by matings among F₁ hybrids are known as F₂ hybrids, while those produced among F₂ hybrids, are F₃ hybrids, and so forth. Backcross hybrids are produced when hybrids mate with either parental type. When the resulting backcross hybrids mate again with the same parental type, the result is the second backcross generation, and so forth. Hybridization occurs in a broad range of organisms — plants, animals, and fungi. Indeed, as we shall see, hybridization is a well-documented phenomenon even among bacteria. NEXT PAGE >>

When Gametes Meet
— by Gene McCarthy
Two gametes meet and say hello.
Perchance their sum is apropos.
But in advance, you cannot know.