Isozyme variation in diploid tropical and octoploid subtropical-temperate species of Bulnesia

Abstract

Isozyme variation for 14 enzyme systems was studied in two diploid tropical species of Bulnesia (Zygophyllaceae), B. arborea and B. carrapo, and in the subtropicaltemperate octoploid, B. bonariensis. The estimated proportions of polymorphic loci for the tropical species appear low, 28.6 percent and 22.7 percent, respectively. The octoploid species had a much higher estimated proportion of polymorphic loci, 46.1 percent, and exhibited complex allozyme phenotypes at some loci. Seed populations of Bulnesia species have genotypic proportions in Hardy-Weinberg equilibrium for esterase and malic dehydrogenase loci. The present study confirms earlier reports that plant and animal polyploids display more genetic variation and biochemical diversity than do diploid species.