Pattern and Process in Strepsirhine Phylogeny

Although Darwin’s ideas concerning the factors and forces responsible for the generation of diversity varied somewhat from one edition of The Origin of Species to the next, by the time he came to write the sixth edition his thoughts had crystallized (Darwin, 1872, p. 129): “Although isolation is of great importance in the production of new species, on the whole I am inclined to believe that largeness of area is still more important, especially for the production of species which shall prove capable of enduring for a long period, and of spreading widely. Throughout a great and open area, not only will there be a better chance of favourable variations, from the large number of individuals of the same species there supported, but the conditions of life are much more complex from the large number of already existing species; and if some of these many species become modified and improved, others will have to be improved in a corresponding degree, or they will be exterminated. Each new form, also, as soon as it has been much improved, will be able to spread over the open and continuous area, and will thus come into competition with many other forms.” (our emphasis)