Diversidade e estrutura genética espacial em população natural de Myrciaria floribunda em Alagoas

Abstract

Myrciaria floribunda is a species native to the Atlantic Forest, belonging to the Myrtaceae family. It naturally occurs in the state of Alagoas, where its fruits are harvested through extractive methods, playing an essential role in the consumption and trade of local communities. However, intensive exploitation poses a threat to the species' genetic diversity and compromises its ability to adapt over time. In order to address this issue, a study on genetic diversity and structure was conducted in a natural population in the state of Alagoas. Young leaves from 30 individuals located in the Environmental Protection Area in the municipality of Piaçabuçu were collected for DNA extraction and PCR-ISSR analysis using 12 primers. To obtain the diversity index among individuals in the population, genetic similarity analysis (Sij) was performed between each pair of individuals using the NTSYSpc2 program. By employing Jaccard coefficients, a dendrogram was generated using the UPGMA method. Genetic diversity was characterized by the following indices: total number of alleles per locus (Na), effective number of alleles (Ne), expected heterozygosity (He), and Shannon's index (I). The analyses were conducted using the Genalex program. The population's genetic structure was based on a Bayesian clustering model using the STRUCTURE v. 2.3.3 program. For the analysis of spatial genetic structure (SGE), the SPAGEDI program was used. The characterization of genotype spatial distribution within populations was based on estimates of coancestry coefficients (θxy) between pairs of plants at different distance classes. Low genetic diversity was found in the population, with Na = 2.00, Ne = 1.20, He = 0.27, and I = 0.15. Through the UPGMA method, two distinct groups were identified, with pairs of individuals CbPia_8 and CbPia_12, CbPia_14 and CbPia_17 showing higher genetic similarity. The population exhibited coancestry values close to zero in all distance classes, indicating a lower degree of relatedness among individuals. Furthermore, it was found that this value was not significantly higher than the upper limit of the 95% confidence interval. Therefore, no spatial genetic structure was observed among the individuals of Myrciaria floribunda. The results emphasize the need for management actions to maximize genetic diversity in the studied population and preserve the natural areas where the species occurs, ensuring its perpetuation in space and time.

Keywords: Genetic conservation; Forest fragmentation; Population genetics.