THE INHERITANCE OF COURTSHIP BEHAVIOR AND ITS ROLE AS A REPRODUCTIVE ISOLATING MECHANISM IN TWO SPECIES OF SCHIZOCOSA WOLF SPIDERS (ARANEAE; LYCOSIDAE)

Abstract

The courtship behaviors of two morphologically similar spider species, Schizocosa ocreata and S. rovneri, are distinctive and prevent interbreeding. We used "forced" copulation between these species to investigate the mode of inheritance of the courtship behavior and to determine whether postmating isolating mechanisms exist. F₁ hybrids proved to be behaviorally sterile, but they were capable of producing viable offspring when forced to interbreed. Analysis of the courtship behaviors of F₁ , F₂ , and backcross progeny showed that the inheritance of some aspects of these behaviors is consistent with models involving single autosomal loci. The inheritance of secondary sexual characteristics in the males is also investigated. The genes for courtship behavior and secondary sexual characteristics do not assort independently. The origin of the premating isolating mechanisms may be explained by either an initial habitat separation between the two groups, or by a founding event with each group subsequently diverging in slightly different habitats. It is suggested that the differences in the microhabitats may have a profound effect on what type of signal (visual or vibratory) would be effective.