Molecular markers applied to the genetic characterization of Dalbergia nigra: implications for conservation and management

Key message Moderate to high genetic diversity and formation of at least three genetic groups were found for Dalbergia nigra ; however, the analyses indicate vulnerability of some populations. Dalbergia nigra is a vulnerable tree species endemic to the Atlantic Forest, known for its economic and ecological potential. To support the conservation and management of D. nigra , the aim of this work was to characterize the diversity and genetic structure of the species through inter simple sequence repeats (ISSR) and simple sequence repeats (SSR) molecular markers. Twelve areas (eleven natural and one planted) were selected in the state of Espírito Santo, Brazil, covering all its regions, called Southern, Central, Northern coastal and Northwestern. In each area, a population was established, totaling 180 adult trees. Molecular markers also indicated populations with the highest and lowest genetic diversity levels, ranging from low to high. For combined data, the Nei ( H * = 0.35) and Shannon ( I * = 0.53) indices calculated with ISSR, and the expected ( H E = 0.57) and observed ( H O = 0.56) heterozygosity calculated with SSR, resulted in moderate to high genetic diversity. Regarding the genetic structure, Amova revealed that the greatest genetic variation is within populations, confirmed by gene flow values ( N m ) greater than 1. Nevertheless, populations were divided into only three distinct groups and the structuring of these groups did not occur homogeneously, indicating that despite the maintenance of the species, some of its populations were affected by forest fragmentation and exploitation, which may lead, in the near future, to increases in the deleterious effects caused by evolutionary factors, in case actions for the conservation and management of the species are not carried out.