Genetic diversity and gene flow in a Caribbean tree Pterocarpus officinalis Jacq.: a study based on chloroplast and nuclear microsatellites.
We analysed the molecular diversity of Pterocarpus officinalis, a tree species distributed in Caribbean islands, South and Central America to quantify the genetic variation within island, to assess the pattern of differentiation and infer levels of gene flow; with the overall goal of defining a strategy of conservation. Two hundred two individuals of 9 populations were analysed using three chloroplast and six nuclear microsatellite markers. The observed heterozygosity varied markedly among the populations for nuclear (H(Onuc )= 0.20-0.50) and chloroplast microsatellites (H (cp )= 0.22-0.68). The continental population from French Guyana showed a higher value of H(Onuc) than island populations, and the differences were significant in some cases. The fixation index F (IS) ranged from -0.043 to 0.368; a significant heterozygote deficit was detected in 7 populations. The heterozygosity excess method suggested that two populations in Guadeloupe have undergone a recent bottleneck. Global and pairwise F (ST) were high for both nuclear (F(STnuc )= 0.29) and chloroplast microsatellites (F(STcp )= 0.58). The neighbour-joining tree based on both markers, presented a differentiation pattern that can be explained by the seed dispersal by flotation and marine stream. The comparison of Bayesian approach and the method based on allelic frequency demonstrate a very limited number of migrants between populations.
Muller
F
F
Biological System Department, CIRAD, Campus international de Baillarguet TA-A 39/C, 34398, Montpellier cedex 5, France. felix.muller@laposte.net
Voccia
M
M
Bâ
A
A
Bouvet
J-M
JM
D001499:Bayes Theorem; D002467:Cell Nucleus / Q000235:genetics; D002736:Chloroplasts / Q000235:genetics*; D003247:Conservation of Natural Resources; D018744:DNA, Plant / Q000032:analysis / Q000235:genetics / Q000302:isolation & purification; D051456:Gene Flow; D014644:Genetic Variation; D018895:Microsatellite Repeats / Q000235:genetics*; D035721:Pterocarpus / Q000145:classification / Q000235:genetics*; D014900:West Indies
D018744:DNA, Plant