The Effects of Habitat Loss on Genetic Diversity and Population Structure of Cedrela fissilis Vell.

Abstract

Cedrela fissilis Vell. has a wide distribution in South and Central America, and in neotropical forests the species occurs at a low density. Its wood is one of the most valued around the world, and the species is currently at risk of extinction due to both habitat fragmentation and illegal logging. Considering the need for conservation strategies, this study aims to investigate the genetic structure, diversity, and inbreeding in C. fissilis populations from the Atlantic Forest. To do this, nine microsatellite loci were used to genotype 289 individuals from eight undisturbed and disturbed fragments. Two of the eight populations harbor most of the genetic diversity: one includes most of the diversity present in all populations and the other is isolated but with high levels of diversity. Genetic diversity was higher within than among populations, with observed and expected heterozygosities ranging from 0.48 to 0.63 and from 0.55 to 0.70, respectively. We detected a significant fixation index, ranging from 0.08 to 0.24 and 32% of the observed alleles were exclusive of some population. The populations showed moderate genetic structure (FST = 0.10) and the Bayesian analysis grouped the studied individuals into three distinct genetic clusters that seem to be related to the presence of geographical barriers. The overall analyses of the results allow us to conclude that protecting only isolated fragments, either large or small, may be ineffective for conserving the C. fissilis gene pool in the studied region. This observation suggests that an appropriate strategy to conserve the gene pool of the species is to maintain both the Atlantic Forest green belt in the eastern portion of the Central and South region of this biome, where the forest is not highly fragmented, as well as the remaining forest areas to the west of the Paraná River.