SYMPATRIC SPECIATION AND EXTINCTION DRIVEN BY ENVIRONMENT-DEPENDENT SEXUAL SELECTION

A theoretical model is studied to investigate the possibility of sympa tric speciation driven by sexual selection and ecological diversificat ion. In particular, we focus on the rock-dwelling haplochromine cichli d species in Lake Victoria. The high speciation rate in these cichlids has been explained by their apparent ability to specialize rapidly to a large diversity of feeding niches. Seehausen and colleagues, howeve r, demonstrated the importance of sex;al selection in maintaining repr oductive barriers between species. Our individual-orientated model int egrates both niche differentiation and a Fisherian runaway process, wh ich is limited by visibility constraints. The model shows rapid sympat ric speciation or extinction of species, depending on the strength of sexual selection.