On the evolution of behavioral reproductive isolation: The Wallace effect
Abstract
A model of speciation is constructed in which two equally fit but cross-sterile interbreeding species W and C meet in a zone of overlap Z. Within the type W population, which is held at a constant proportion γ of Z by migration from the outside, a mutation arises which causes a partial aversion to individuals of type C. Formulas for the expected frequency of the various possible mating pairs in Z are derived, and an approximation for small aversion is found. The increase in frequency of the mutant gene in the type W population in Z is the found to be approximately pq(1 ‑ γ)[ r 1(1 ‑ 2 p) + r 2 p], where p is the relative proportion of the mutant gene in the type W population, q = 1 ‑ p, and r 1 and r 2 are the aversion probabilities for mutant heterozygotes and homozygotes, respectively. The resulting selective pressure towards behavioral reproductive isolation is discussed.
- Publication:
-
Theoretical Population Biology
- Pub Date:
- January 1981
- DOI:
- 10.1016/0040-5809(81)90021-6
- Bibcode:
- 1981TPBio..19..261S