GENETIC DIVERSITY AND STRUCTURE ASCLEPIAS CONTRAYERBA SESSE AND MOC. (APOCYNACEAE: ASCLEPIADOIDEAE) IN MEXICO

Asclepias contrayerba is one of the 250 species known for the genus and have your distribution in the center, northwest and southwest of Mexico, they have importance in the medicinal folk by the presence of precursors of alkaloids in the root. The principal objetive of this work is know the diversity and genetic structure of five populations localized in Tlaxcala, Jalisco and Guerrero and known the effect of traditional use in the reduction of genetic variation. The genetic populations values has been obtained by electrophoresis with starch gel for 20 isozymes. The genetic diversity estimate for the mean of alleles by locus is A = 2.0, the percentage of polymorphic loci is P = 100 %, the calculated heterocygosis H-E is of 0.413 and the observed H-O of 0.388, the fixation index (F) is of 0.142. For genetic structure, F-IT is of 0.205, F-IS of 0.087 and F-ST of 0.128. The global diversity genetic is considered as high respect to others species with similar live history. However, to population level, the two of Tlaxcala and one of Jalisco the plants have high heterocygosis, probably by widespread pollination. In the populations of Guerrero and Jalisco, there are plants with high homocygosis and can be by some phenomen that limit the presence of pollination. By end, the results have demonstrated that the traditional use of the root don't have influence on the diversity and genetic structure of this specie.