Spatial scales of gene dispersal within natural populations of Anadenanthera colubrina var. cebil (Leguminosae) a keystone tree species

GONCALVES, ALEJANDRA LORENA; GARCÍA, MARÍA VICTORIA

Foz do Iguaçu

Congreso; XXII International Congress of Genetics; 2018

Brazilian Genetics Society (SBG), Latin American Association of Genetics (ALAG), International Genetics Federation (IGF)

Pollen and seed dispersal are key processes by mean plants exchange genes. Thus, fine-scale spatial genetic structure (FSGS) within populations depends on the distances of seed and pollen dispersal. In order to understand the role of gene dispersal in shaping the FSGS in populations of Anadenanthera colubrina var. cebil, we investigated the spatial scale of gene dispersal within A. colubrina var cebil populations and the neighborhood size in these populations. Adults and saplings of A. colubrina var cebil were located in Campo San Juan reserve (Misiones, Argentina), although all adult individuals were genotyped by mean of eight nuclear microsatellite markers. FSGS was evaluated based on pairwise kinship at different distance classes. The neighborhood size (Nb) and the historical gene dispersal distances (σg) for different effective densities (De) were estimated. Short dispersal distances were further supported by strong FSGS (Sp=0.01) and by short σg (5-17m); the relatedness between mating individuals was higher than expected by chance, and the Nb was in the range between 108 and 138 individuals. While De reaches high level, the value of Nb decreases, as a consequence of this the effects of genetic drift could be strong. The limited seed dispersal could promote the aggregation of trees, and this mechanism could enhance the correlation between gene and seed dispersal. In this way, high De and low rates of gene dispersal reduce the Nb. Thus, a small Nb increases mating between relatives and the FSGS within the studied populations of A. colubrina var. cebil.