Use of SSR Fragment Length Homozygotes for Orangutan Systematics

ABSTRACT. The use of simple sequence repeat (SSR) loci lacking length polymorphisms among their alleles (defined here as homozygotes) in systematic studies has thus far been largely ignored due to their apparent lack of genetic heterogeneity. However, in this paper we show that point mutations, insertions, and deletions within SSR loci of identical size can be highly informative for population genetic and evolu-tionary studies. Our preliminary study of the von Willebrand factor (vWF) locus shows that there is a sig-nificant level of divergence among the Bornean Orangutans which implies that present orangutan subpopulations in Borneo are genetically isolated from each other. However, our findings do not confirm that the Bornean and Sumatran Orangutans form two separate clades. Key Words: Pongo pygmaeus; Microsatellite polymorphism; vWF; Phylogenetic analysis; Conservation