Chapter 8: Hybridism Summary and Analysis

When two organisms of distinct species are interbred, the resulting hybrid offspring is sterile. It is often thought that this intended in nature to prevent all of the various species from intermingling and, as a result, losing the distinctions between them. If this were so, this would support the belief that the species were independently created and, therefore, undermine the theory that the species were produced by natural selection.

It should first be noted that two different facts are often confused when studying this subject, namely, the sterility of two species when breeding with one another and the sterility of the resulting offspring. In other words, there is the question of whether two distinct species can produce offspring at all and, second, whether the offspring of two distinct species is itself capable of producing offspring. Now, studies that attempt...