GENETIC VARIATION BETWEEN Lupinus elegans Kunth PROVENANCES, ALTITUDINAL SEED ZONING AND ASSISTED MIGRATION

Lupinus elegans Kunth is a species used in ecological and agroforestry reforestation programs in Mexico and other countries. It is tolerant to conditions of stress and it fixes nitrogen. To understand the structure of genetic differentiation among populations and to match genotypes to contemporary and future (due to climate change) environments, this study evaluated genetic variation of quantitative traits among 12 populations of L. elegans, collected along an altitudinal gradient in the east-central region of Michoacan. In August 2009, field provenance trials were planted (pine-oak forest, site La Cruz, near La Mina and the panoramic lookout Mil Cumbres, in east-central Michoacan, 2700 m altitude), with a complete randomized block design. For the trial site, mean annual temperature and precipitation were estimated, and an annual aridity index was calculated for contemporary climate and for the climate in 2030. At 10 months of age, plant height and aerial biomass were recorded. Using an analysis of variance, significant genetic differences in height (p=0.001) and aerial biomass (p=0.001) were detected among the populations. Plant height and biomass were associated with the provenance altitude of the populations; populations originating from higher altitudes had taller plants (r(2)=0.49; p <= 0.011) and more biomass (r(2)=0.48; p <= 0.011) than the populations at lower altitudes. Apparently, the L. elegans populations have differentiated genetically in response to a selection gradient, consisting of colder, more humid sites at higher altitudes, and hotter, drier sites at lower altitudes. For collection and management of seed destined for ecological restoration and conservation, four altitudinal zones of 150 m of altitudinal range each were defined: 2300, 2450, 2600, 2750 and 2900 m. Due to the need for assisted migration of L. elegans to compensate the climate change predicted for 2030, it is recommended that populations of this species be moved approximately 550 m higher in three successive movements of 150 m each.