The objective of this study was to investigate genetic diversity, genetic structure and effective size retained in a germplasm bank formed by two populations of Myracrodruon urundeuva Fr. All. (aroeira) from Aramina-SP and Selvíria-MS. The populations were evaluated from the sample of 25 open-pollinated progenies of each population. From each progeny, 17 to 20 individuals were sampled and genotyped for eight microsatellite loci. The greatest values for the total number of alleles (At), average number of alleles per locus (Ae), effective number of alleles per locus (A), observed heterozygosity (H0) and expected heterozygosity (He) were detected in Selvíria population (At=105, A=13.13, Ae =3.98, H0) =0.669 and He =0.749) in comparison to Aramina (At =94, A =13.75, Ae =3.10, H0=0.535 and He =0.678). The differentiation in allele frequencies between the two populations for the outcross-pollen (0.159) and ovules (0.235), indicate that about 84% and 77% of genetic diversity was within populations. The average coancestry coefficient was higher (Selvíria Θ =0.165, Aramina Θ =0.169) and the average effective population size within progenies (Selvíria Ne(v) =3.04, Aramina Ne(v) =2.69) was lower than expected in progenies of panmitic populations (Θ=0.125, Ne(v) =4). The total effective population size retained in the ex situ bank was estimated in 67.5 in Selvíria population and 71.1 in Aramina population, which values lower than the required (Ne =150) for short terms population conservation. However, the two populations showed high genetic diversity, which qualifies them for use in conservation and breeding programs of the species, provided the ex situ conserved population effective size is increased.
Inbreeding; Microsatellites; Tropical tree species
