You are not currently logged in.
Access your personal account or get JSTOR access through your library or other institution:
If You Use a Screen ReaderThis content is available through Read Online (Free) program, which relies on page scans. Since scans are not currently available to screen readers, please contact JSTOR User Support for access. We'll provide a PDF copy for your screen reader.
Speciation as a Stage in Evolutionary Divergence
The American Naturalist
Vol. 74, No. 753 (Jul. - Aug., 1940), pp. 312-321
Stable URL: http://www.jstor.org/stable/2457524
Page Count: 10
Since scans are not currently available to screen readers, please contact JSTOR User Support for access. We'll provide a PDF copy for your screen reader.
Preview not available
By speciation is meant the fixation of discontinuity among organisms. Discontinuity is maintained by isolating mechanisms that prevent the interbreeding of carriers of different adaptive complexes of genes. A theory is suggested according to which the development of isolating mechanisms follows, rather than accompanies, that of the adaptive complexes themselves. The development of physiological isolation takes place principally along the geographical boundaries separating the distribution areas of the incipient species. Some evidence for and against this theory is discussed.
The American Naturalist © 1940 The University of Chicago Press