Phenological variation within and among populations of Plathymenia reticulata in Brazilian Cerrado, the Atlantic Forest and transitional sites.

BACKGROUND AND AIMS: Plathymenia reticulata (Leguminosae) is a Brazilian tree that occurs in two biomes: Cerrado, a woody savanna vegetation, and the Atlantic Forest, a tropical forest. In this study, phenological patterns and their variability within and among populations located in these biomes and in transitional zones between them were assessed. METHODS: During a 15-month period, individuals from two populations in Cerrado, two in the Atlantic Forest, and six in transitional zones (three in a cerrado-like environment and three in forest fragments) were evaluated in Minas Gerais State, Brazil. The individuals were evaluated monthly according to the proportion of the canopy in each vegetative phenophase (leaf fall, leaf flush and mature leaves) and each reproductive phenophase (floral buds, flowers, immature fruits and mature fruit/seed dispersal). In order to assess the phenological variability within and among populations, habitats and biomes, the Shannon-Wiener diversity index, the Morisita-Horn similarity index and genetic population approach of partitioning diversity were used. KEY RESULTS: Populations of P. reticulata, in general, showed similar phenology; the main differences were related to leaf fall, a process that starts months earlier in the Cerrado than in transitional sites, and even later in forest areas. Considerable synchrony was observed for reproductive phenology among populations and between biomes. Most phenological diversity was due to differences among individuals within populations. CONCLUSION: In spite of environmental differences, P. reticulata from the Atlantic Forest and Cerrado showed similar phenological behavior with only about 10% of the total diversity being attributed to differences between biomes.

Genetic, morphological and spatial characterization of two populations of Mabea fistulifera Mart. (Euphorbiaceae), in different successional stages

Duas populações de Mabea fistulifera (Euphorbiaceae) localizadas no Parque Estadual do Rio Doce (Minas Gerais, Brasil), mas em locais caracterizados como em diferentes estágios sucessionais, foram investigadas quanto a parâmetros genéticos e ecológicos. Em cada população, 20 indivíduos escolhidos de forma aleatória, foram avaliados quanto à presença de 43 marcadores RAPD, cinco características morfológicas e quanto à distribuição espacial. O índice de Shannon e a AMOVA revelaram que a maior parte da variação genética está localizada entre indivíduos dentro das populações, com apenas cerca de 9% da variação entre populações. As populações diferem geneticamente, mas possuem valores similares de diversidade genética. Os dados morfológicos revelaram marcantes diferenças entre as populações. Foram obtidas correlações significativas entre matrizes de distâncias genéticas, geográficas e morfológicas, considerando-se ambas as populações. Os dados revelaram ainda que dentro de uma mesma população, indivíduos espacialmente mais próximos tendem a ser mais semelhantes geneticamente. Os resultados são discutidos a respeito da biologia da espécie e das características das populações.