Selective Mating in the Earthworm (Lumbricus Terrestris L.)

Selective or assortative mating has been discussed under the term homogamy, which has been defined by Harris (3) as the mating of physically or psychically similar individuals. The phenomenon has been observed in the plant kingdom [see D. F. Jones (5) J and in several phyla of the animal kingdom, including Protozoa and Chordata. Willoughby and Pomerat (9) have reviewed homogamy with respect to physical characters, and the evidence for influence of psychic factors in mate selection has been summarized by H. E. Jones (6) and Schiller (8). This paper will report (1) certain quantitative findings on the existence and degree of assortative mating in Lumbricus terrestris L., a representative of the phylum Annelida, the homogamic tendencies of which have not previously been investigated; (2) the significance of the mechanism of mating in another hermaphroditic form; (3) the effect of environmental factors on the intensity of homogamy in this particular species; and (4) evidence for the role of homogamy in establishing or maintaining new populations of earthworms