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We report the population genetic structure of the endangered tropical tree species Caryocar brasiliense, based on variability at 10 microsatellite loci. Additionally, we compare heterozygosity and inbreeding estimates for continuous and fragmented populations and discuss the consequences for conservation. For a total of 314 individuals over 10 populations, the number of alleles per locus ranged from 20 to 27 and expected and observed heterozygosity varied from 0.129 to 0.924 and 0.067 to 1.000, respectively. Significant values of theta and R(ST) showed important genetic differentiation among populations. theta was much lower than R(ST), suggesting that identity by state and identity by descent have diverged in these populations. Although a significant amount of inbreeding was found under the identity by descent model (f = 0.11), an estimate of inbreeding for microsatellite markers based on a more adequate stepwise mutation model showed no evidence of nonrandom mating (R(IS) = 0.04). Differentiation (pairwise F(ST)) was positively correlated with geographical distance, as expected under the isolation by distance model. No effect of fragmentation on heterozygosity or inbreeding could be detected. This is most likely due to the fact that Cerrado fragmentation is a relatively recent event (approximately 60 years) compared to the species life cycle. Also, the populations surveyed from both fragmented and disturbed areas were composed mainly of adult individuals, already present prior to ecosystem fragmentation. Adequate hypothesis testing of the effect of habitat fragmentation will require the recurrent analysis of juveniles across generations in both fragmented and nonfragmented areas.

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In this work we report on the phylogeography of the endangered tree species Caryocar brasiliense based on variability in two classes of maternally inherited chloroplast DNA sequences with different rates of molecular evolution. Eleven sequence haplotypes of a noncoding region between the genes trnT and trnF and 21 distinct 10-locus microsatellite haplotypes could be identified in a total of 160 individuals, collected in 10 widespread populations of C. brasiliense. An amova indicated that most of the variation can be attributed to differences among populations, both for DNA sequence (87.51%) and microsatellites (84.38%). Phylogeography based on a median-joining network analysis of the noncoding region showed a sharp difference from the analysis of microsatellite haplotypes. Nevertheless, both analyses indicated that multiple lineages may have contributed to the origin of C. brasiliense populations in Brazilian Cerrado. Incongruences in the microsatellite haplotypes network suggest that homoplasy, which emerged from recurrent and independent mutations, greatly influenced the evolution of the C. brasiliense chloroplast genome. We hypothesize that our results may show the outcome of the restriction of ancient relic populations to moist refugias during extended droughts coinciding with glaciation in the northern hemisphere. The subsequent spread to favourable areas throughout Central Brazil may have caused contact between different lineages during the interglacial periods. The extinction of megafauna dispersers in the last glaciation may have caused a restriction in seed movement and currently, gene flow has been occurring mainly by pollen movement.

RESUMO: Foram selecionadas seis áreas de estudo, Estação Ecológica de Águas Emendadas-DF, Parque Nacional de Brasília-DF, APA Gama-Cabeça do Veado-DF, Silvânia-GO, Paracatu-MG e Pat rocínio-MG na Chapada Pratinha (15-20'" S e 46-49~ W), três delas em unidades de conservação e três fora delas. Em cada área foram amostradas 10 parcelas de 1000 m 2 (20xSOm). Todas as árvores a partir de 5 cm de diâmetro na base do tronco foram medidas e identificadas. A florística ea fitossociologia de cada área foi analisada e estas foram comparadas entre si pelos índices de similaridade de S0rense e de Morisita. No total foram encontradas 139 espécies e 42 famílias sendo que ape nas 22 espécies foram comuns a todas as áreas. Leguminosae e Vochysiaceae apresentaram valores de im!XIrtância elevados em todas as áreas. As densidades !XIr ha variaram de 664 a 1396. Os índices de diversidade de Shannon variaram de 3,1 1 a 3.56. As similaridades foram altas pelo índices de Sorensen, de 0,5 a 0,7, !XIrém baixas pelo de Morisita quando se comparou as áreas de Paracatu e Patrocínio com as demais áreas. Foi concluído que as diferenças florísticas e principalmente estruturais foram elevadas entre estas duas áreas que são mais distantes e se situam a menores altitudes do que aquelas si tuadas nas unidades de conservação existentes na chapada sendo sugerida a criação de novas unidades nestes Municípios.