GENETIC VARIATION AMONG AND WITHIN CANDEIA ( Eremanthus erythropappus (DC.) MacLeish ) POPULATIONS

Entre as esp\ue9cies indicadas para a restaura\ue7\ue3o da vegeta\ue7\ue3o arb\uf3rea em s\uedtios degradados no sul de Minas Gerais, destaca-se a candeia (Eremanthus erythropappus (DC.) MacLeish), que ocorre naturalmente em solos pobres e pedregosos, al\ue9m de possuir atributos relativos \ue0 durabilidade natural da madeira e \ue0 qualidade de \uf3leo essencial para uso na farmacologia. O sucesso da recupera\ue7\ue3o dessas \ue1reas est\ue1 relacionado com a rapidez com que a vegeta\ue7\ue3o \ue9 restabelecida. Assim, a busca de gen\uf3tipos superiores e adaptados, que possam rapidamente recolonizar a \ue1rea, \ue9 de grande import\ue2ncia econ\uf4mica e ambiental. Neste estudo, foram coletadas sementes de poliniza\ue7\ue3o livre de 27 matrizes em duas popula\ue7\uf5es de candeia distintas, S\ue3o Tom\ue9 das Letras e Carrancas, localizadas no Estado de Minas Gerais. Ap\uf3s a germina\ue7\ue3o, as mudas foram repicadas para tubetes e arranjadas em blocos casualizados completos, com tr\ueas repeti\ue7\uf5es. Tr\ueas meses ap\uf3s a repicagem, foi avaliada a varia\ue7\ue3o entre e dentro das popula\ue7\uf5es. Verificou-se, pela an\ue1lise de vari\ue2ncia, que existem diferen\ue7as significativas entre e dentro de popula\ue7\uf5es para o car\ue1ter di\ue2metro do caule. As varia\ue7\uf5es entre as prog\ueanies foram significativas dentro da popula\ue7\ue3o de S\ue3o Tom\ue9 das Letras para o di\ue2metro, e, dentro da popula\ue7\ue3o de Carrancas, para o car\ue1ter altura total das mudas. Por\ue9m, para a sele\ue7\ue3o de gen\uf3tipos, \ue9 necess\ue1rio maior tempo de avalia\ue7\ue3o, visto que grande parte da varia\ue7\ue3o apresentada na fase de mudas pode ser decorrente do efeito materno, o qual n\ue3o \ue9 transmitido para a gera\ue7\ue3o seguinte.Among the suitable species for restoration of arboreal vegetation in degraded lands in the south of Minas Gerais, candeia trees (Eremanthus erythropappus (DC.) MacLeish) stand out because they occur and regenerate naturally in stony and poor sites. Besides, they have good attributes related to the natural durability of wood and the quality of essential oil for use in pharmacology. The success of restoration is related to the speed with which the vegetation is reestablished. Hence, the search for superior and adapted genotypes, which are able to colonize the area quickly, is of great economical and environmental importance. Open-pollinated seeds were collected from 27 mother trees in two distinct populations: S\ue3o Tom\ue9 das Letras and Carrancas, Minas Gerais state, Brazil. The germinated plantlets were arranged in a randomized block design with three replications containing seedling from the 27 open-pollinated progenies. After three months of seedling grown in containers, the genetic variation among and within seed populations was evaluated. The analyses of variance showed that there were significant differences among and within populations in stem diameter. Within S\ue3o Tom\ue9 das Letras population, the variation among progenies was significant in diameter and, within Carrancas population, only in seedling height the variation was significant. However, a longer term of evaluation is required for the sake of genotype selection of candeia, since a large extent of the manifested variation in seedlings stage might be due to inheritance of maternal influences that will not be transmitted for the following generations

Genetic differentiation of the neotropical tree species Protium spruceanum (Benth.) Engler (Burseraceae) between fragments and vegetation corridors in Brazilian Atlantic forest

We studied patterns of genetic differentiation in a connected landscape with an interesting history of human habitat conversion that began two centuries ago, during the Brazilian colonization period. In the fragments of Brazilian Atlantic seasonal forest and corridors of secondary forest, Protium spruceanum is an abundant native, mass-flowering/insect-pollinated and bird-dispersed tree. Genetic diversity was analyzed from 230 individuals in five fragments (1 to 11.8 ha) and four corridors (460 to 1000 m length) using allozyme loci. We did not find evidence of inbreeding within fragments or corridors, but the proportion of heterozygotes (<IMG SRC="/img/revistas/abb/v23n4/a28simb1.gif" WIDTH=287 HEIGHT=96>) were significantly higher in fragments than in the secondary vegetation corridors, based on Goudet's G-test (P = 0.036). Genetic differentiation was low and no pattern of isolation by distance was detected. All fragments generally present low historical genetic differentiation with corridors that they are connected, indicating possible gene flow via seeds and pollen. Due to the consistently low differentiation observed among them and the absence of a significant reduction in gene diversity in second-growth forests, we conclude that corridors of second-growth forests would be an important alternative in the genetic connection of isolated forest fragments