Distribución de la diversidad genética de Diomate (Astronium graveolens Jacq) en el bosque seco tropical de Colombia

Abstract

The Tropical Dry Forest degradation is accompanied by a loss in the genetic diversity of tree species contained in it, limiting opportunities for the implementation of conservation and restoration programs that embrace genetic diversity to enhance the capacity of ecosystems to adapt to environmental changes. We studied the genetic diversity and structure of Astronium greveolens, a representative species of the Tropical Dry Forest ecosystem, in 10 local populations located in remnants of this ecosystem in Colombia. The genetic diversity information was obtained from molecular microsatellite markers and it was compared with the modeled spatial distribution of the ecosystem in the present and past (Last Glacial Maximum (LGM) and mid-Holocene (MH)). We identified three genetic groups in the populations. The populations located in the Caribbean region presented the highest diversity ranges. The population located in Guamo, Bolívar in addition to holding high diversity showed evidence of inbreeding. Patterns in habitat suitability under past climates and richness of locally common alleles might explain possible processes of expansion and suggest that the Chicamocha populations harbor the genetic diversity that gave rise to the current A. graveolens populations in the Caribbean region. Most of the populations sampled showed heterozygosity scores close to the Hardy-Weinberg expectations. However, the positive values of inbreeding coefficient found at the Guamo population together with its importance for harboring high levels of locally common alleles, suggest this is a priority area for conservation and restoration efforst. The lowest diversity values are associated with areas with lower niche coverage, such as the “Valle del Cauca” populations, where even in past periods (LGM and MH) the niche suitability is presented in small fragments compared to those identified in the Caribbean region.