Reproductive Isolation and the Integrity of Two Sympatric Species of Choristoneura (Lepidoptera: Tortricidae)

According to Dobzhansky (1951a, p. 262) “Species are … groups of populations the gene exchange between which is limited or prevented by one, or by a combination of several, reproductive isolating mechanisms”. This definition follows from his concept of a species not as a static unit but as a stage in the process of evolutionary divergence. Limitation or prevention of gene exchange is a property of geographic and reproductive isolation (Mayr, 1912), the various types of which Dobzhansky lists as follows: I. Geographic or Spatial Isolation II. Reproductive Isolation A. Ecological Isolation B. Seasonal or Temporal Isolation C. Sexual, Psychological or Ethnological Isolation D. Mechanical Isolation E. Gametic Isolation F. Hybrid Inviability G. Hybrid Sterility H. Hybrid Breakdown