SEXUAL SELECTION AND GENETIC-RELATIONSHIPS OF A SIBLING SPECIES COMPLEX OF BOWER BUILDING CICHLIDS IN LAKE MALAWI, AFRICA

Protein electromorphs of five taxa of the sand dwelling genus Tramitic hromis from Lake Malawi were examined by starch-gel electrophoresis. T wenty-four enzyme loci were examined. No diagnostic alleles were disco vered which distinguished the different taxa; however, nine loci were polymorphic in at least one taxa with unbiased mean heterozygosities r anging from 6.9 to 12.6%. The bower form of these five taxa, which ear lier have been referred to as sibling species was also analyzed. Resul ts from this study provide evidence that bower form in these cichlid t axa is correlated with genetic distance measurements. The data suggest that the taxa are isolated 'sibling' species, which recently diverged , or that they are 'incipient' species with minimal gene flow between bower building morphs. The congruence of the allozyme data suggests a genetic basis for bower form. Variation in bower form is hypothesized to arise from nonadaptive differences in female choice, which leads to reproductively isolated species as predicted by Fisher's model of run away sexual selection.