Genetic diversity and structure of natural populations ofPlathymenia reticulata(Mimosoideae), a tropical tree from the Brazilian Cerrado

Abstract

Plathymenia reticulata is a tropical tree native to the Brazilian Cerrado, one of the most important and endangered ecosystems in Brazil. This species presents high-quality wood and potential for recovery of degraded areas. Despite its importance, almost nothing is known about its genetic or ecological features. Random amplified polymorphic DNA (RAPD) markers were used to investigate the genetic diversity and structure of six natural populations of P. reticulata. DNAs from 117 adult individuals were amplified with 10 random primers and Shannon's index and amova were used to evaluate the levels of genetic diversity within and among populations. Through 72 markers, 70.8% of which were polymorphic, it was possible to obtain 117 unique RAPD phenotypes. The levels of genetic variability found in the six populations of P. reticulata were considerable and most of the genetic variation was found between individuals within populations, although pairwise PH(ST) values indicated significant divergence between populations. The among-population component accounted for, respectively, 12.3% and 16% of the genetic variation, according to amova and Shannon's index. These results were compared with other genetic studies on plant species and such a level of differentiation among populations corresponds to that which has usually been observed for outcrossing plants. The importance of maintenance of the P. reticulata populations and implications of the analysis of adult individuals, considering the longevity of this species and the relatively recent Cerrado fragmentation, are discussed.

Genetic structure and gene flow of Eugenia dysenterica natural populations

“…An approximate mean number of migrants per generation (Nm) was calculated through the expression: Nm = 0.25(1/F ST -1) (Wright, 1951), in which F ST was substituted by its analog φ ST (Lacerda et al, 2001), which means the proportion of molecular variability among populations. In this expression, N is the populational size, and m is the proportion of migrants per generation.…”

Geographic pattern of genetic diversity in natural populations of Rosewood (Aniba rosaeodora), in the Central Amazonia

“…Fisher's exact test (Raymond & Rousset, 1995) was used to detect disequilibria in the band frequencies among populations, using tFPga software (miller, 1997) and selecting the corrections options for RaPD bands (lynch & milligan 1994). the distribution of genetic diversity within and among populations was tested by analysis of molecular variance (amova) using arlequim 2.0 (Schneider et al, 2000), which is appropriate for RaPD diversity analyses (excoffier et al, 1992;Huff et al, 1993;Stewart & excoffier, 1996;lacerda et al, 2001). nei's diversity index (nei, 1973) was calculated in PoPgene, and correlated to the number of trees (Pearson´s correlation, p < 0.005) in order to verify any bias caused by number of trees sampled from different populations (37 in manaus and 24 in the other populations).…”

Variabilidade e caracterização de frutos de pitangueiras em municípios baianos

“…A caracterização constitui uma das principais etapas dos trabalhos com germoplasma, pois permite indicar plantas com potencial de uso imediato, bem como identificar genótipos que apresentem características interessantes para o melhoramento, além de ser fundamental para o estabelecimento de formas de exploração econômica e racional (LACERDA et al, 2001). Sem o conhecimento das características agronômicas, morfológicas e citogenéticas, não é possível manipular adequadamente a variabilidade genética observada (MELETTI et al, 1992) A caracterização morfológica consiste na aferição de caracteres botânicos herdáveis, facilmente visíveis e mensuráveis que, a princípio, podem ser expressos em todos os ambientes.…”