Genetic diversities of four little-known species of Malesherbia (Malesherbiaceae) endemic to the arid inter-Andean valleys of Peru

Few studies of genetic variation have been conducted on plants of the Pacif ic coastal desert and neighboring Andes of Peru, although the region has ma ny endemic taxa. Enzyme electrophoresis was employed to examine allozyme di versities of four species of the family Malesherbiaceae, an endemic to the arid Andes and coastal desert. One population of Malesherbia splendens and two of M. tubulosa, both endemics of the department of Lima, one population of M. weberbaueri var. weberbaueri, an endemic of the Andean department Hu ancavelica, and the two Lima populations of M. scarlatiflora were studied. Fifteen loci were examined for all populations and an additional seven loci were resolved for M. weberbaueri and M. splendens. Malesherbia splendens, which is known from three populations, has a low mean number of alleles per locus (A), proportion of polymorphic loci (P), and expected heterozygosity (H-s) (A = 1.214, P = 0.214, H-s = 0.057). Malesherbia weberbaueri (A = 1. 231, P = 0.154, H-s = 0.079) and M. scarlatiflora (A = 1.364, P = 0.273, H- t = 0.083) both have average expected heterozygosities and relatively low m ean numbers of alleles per locus and proportions of polymorphic loci. In M. tubulosa, all measures of genetic diversity are high in comparison with ot her endemics (A = 1.818, P = 0.364, H-t = 0.206). Malesherbia tubulosa has high interpopulation differentiation, whereas M. scarlatiflora has low amon g-population diversity. The relatively low allozyme diversities, restricted habitats, narrow ranges of M, splendens and M. M weberbaueri, and the morp hological similarities of all four species suggest that they evolved recent ly by founder events. Greater allozyme diversities in M. tubulosa could be attributable to its maintenance of larger populations in a greater variety of habitats.