Spatial genetic structure in natural populations of Caryocar brasiliense Camb. (Caryocareceae) in the North of Minas Gerais, Brazil

Abstract

Caryocar brasiliense is a widely distributed but endangered Brazilian Cerrado tree species. We studied patterns of spatial genetic structure and populational differentiation from four natural populations in the North of the State of Minas Gerais, Brazil. Genetic diversity from 240 individuals using allozyme loci was analyzed and inferred by heterozygosity index, Nason's kinship coefficient and assessment of historical population bottlenecks. We did not find evidence of inbreeding within fragments, but from the fitting tests into the infinite allele model of mutation no population was shown to be in equilibrium, indicating recent bottlenecks. Only one population (Japonvar) showed positive coancestry value indicating the tendency of increased structure among trees that are spatially closer to each other. Although the average genetic differentiation in each population pair was generally low (DG = 0.036), Mantel tests showed tendency for distance dependence of genetic structure (rm = 0.905, P = 0.084). Fragmentation may cause genetic isolation by next generations, increasing differentiation among populations. Thus, considering the practically irreversible fragmentation of populations around agricultural areas at Cerrado Biome, landscape management strategies for C. brasiliense should be considered to protect the still existent populations.