Lupinus elegans KUNTH ASSISTED MIGRATION IN COMMON GARDEN FIELD TESTS

Abstract

Lupinus elegans is a species used in ecological restoration and agroforestry programs, because it is tolerant to stress and fixes nitrogen. Genetic variation in quantitative traits was studied in six populations of L. elegans collected along an altitudinal gradient (2312 to 2885 m) in the Mil Cumbres region, east-central Michoacán state, México. Provenance tests were planted at 2600 and 2800 m altitude in two common garden field trials. Tests aimed to evaluate the performance at a different altitude than the site of the seed source, simulating an altitudinal-assisted migration. Survival, plant height growth and aerial biomass were measured. For each provenance and experimental sites, climatic variables were estimated for contemporary climate (average 1961-1990) and future climate (decade centered in 2030, by averaging six model scenarios). It was estimated that by the year 2030 there will be, on average, an increment of 1.4 °C in mean annual temperature, an increase of 518 degree-days > 5 °C (DD5), a 90 mm decrease in mean annual precipitation (MAP) (-7.3 % of contemporary MAP), and a 0.0077 increase in an aridity index (DD50.5/MAP). An ANOVA for each site revealed that in the higher altitude site (2800 m) populations exhibited a pronounced pattern of genetic differentiation (P = 0.0001), in which plant height and biomass are associated with the transfer distance between their place of origin and the experimental site. This distance can be expressed in difference in altitude, mean annual temperature, or aridity index. At the site at higher altitude, plants originated from populations growing at higher altitudes were taller and had more biomass than those originated grown at lower altitudes (R² ≥ 0.85, P ≤ 0.0302). In contrast, in the lower altitude site (2600 m), although there were nearly significant differences (P ≤ 0.0615) between populations for all of the variables, there was no clinal pattern. In general, the populations grew less when they were moved away from their original climate: those from the higher altitudes grew less in the 2600 m site, and those from the lower altitudes grew less in the 2800 m site. This indicates that climate change will likely induce less growth in several populations, thus it is recommended to promote gradual assisted migration.