Spatial genetic structure, genetic diversity and pollen dispersal in a harvested population of Astrocaryum aculeatum in the Brazilian Amazon

Abstract

BackgroundAstrocaryum aculeatum is a palm tree species native to the tropical regions of South America, exploited commercially by local farmers for the pulp extracted from its fruits. The objective of this research was to compare the genetic diversity between adult plants and seedlings from open-pollinated seeds, quantify the pollen flow and dispersal, the spatial genetic structure, and the effective size of a population that has been continuously harvested for its fruits. The study was carried out in a natural population of A. aculeatum distributed over approximately 8 ha in the State of Amazonas (Brazil), separated by 400 m from the closest neighboring population. In total, 112 potential pollen donors, 12 mother plants and 120 offspring were mapped and genotyped.ResultsGenetic diversity was high for parents and the offspring. The fixation indexes for adults (F = -0.035) and offspring (F = -0.060) were negative and not significant. A significant spatial genetic structure was detected for the adult plants (up to the distance of 45 m) indicating short-distance seed dispersal. Paternity analysis detected 9.2 % of pollen immigration and the average distance of pollination within the population was 81 m. The average effective pollination neighborhood area between plants was 1.51 ha.ConclusionsOur results indicate that substantial introduction of new alleles has occurred in the population through pollen immigration, contributing to the maintenance of genetic diversity. Conservation efforts aimed at maintaining the gene pool of the current population or establishing new populations should utilize offspring from mother plants selected to be spaced by at least 50 m to prevent collecting seeds from relatives.

Research Article Population genetic structure of three species in the genus Astrocaryum G. Mey. (Arecaceae).

“…aculeatum, A. murumuru, and A. paramaca. Levels of genetic diversity (H E and H O ) found for the species of Astrocaryum presented here were also lower than most of the literature available for other palm species using microsatellite markers, which showed a minimum estimate for H E of 0.5 (Conte et al, 2008;Elshibli and Korpelainen, 2008;Choo et al, 2010;Namoff et al, 2011;Ottewell et al, 2012;Nazareno and dos Reis, 2014;Ramos et al, 2016). Nevertheless, similar results for H E and H O were found for Chamaerops humilis, with a mean N A equal to 3.67 and H E and H O equal to 0.374 and 0.366, respectively (Giovino et al, 2014).…”

“…Nevertheless, similar results for H E and H O were found for Chamaerops humilis, with a mean N A equal to 3.67 and H E and H O equal to 0.374 and 0.366, respectively (Giovino et al, 2014). It is worth mentioning that studies with other congeners of Astrocaryum (Oliveira et al, 2014;Ramos et al, 2012Ramos et al, , 2016) that used the same microsatellite set used here, excluded monomorphic loci from the estimation of genetic diversity; this automatically increased the estimates for these parameters [given the formula used to calculate heterozygosity (H = 2 ( 1)…”

“…Other population genetic structure parameters, such as Wright's inbreeding coefficient and gene flow, have shown that, in general, genetic differentiation (F ST ) is low, indicating genetic variation higher within -rather than among -populations and a high gene flow among populations (Elshibli and Korpelainen, 2008;Martins-Corder et al, 2009;Shapcott et al, 2009;Namoff et al, 2011;Silva et al, 2011;Giovino et al, 2014;Nazareno and dos Reis, 2014;Oliveira et al, 2014;Moura et al, 2015). Recently, Ramos et al (2016) found a high level of genetic diversity, mostly within populations, for adults and seedlings in populations of A. aculeatum, and along with results for spatial genetic structure indicated short-distance seed dispersal and modest levels of pollen flow. To date, there is no information regarding the level and distribution of genetic diversity for A. murumuru and A. paramaca, which is needed to evaluate the potential of them as potential crop species.…”

Paternity analysis, pollen flow, and spatial genetic structure of a natural population ofEuterpe precatoriain the Brazilian Amazon

“…The genetic diversity analysis (Table 1) shows that E. precatoria is a species that maintains similar patterns of genetic diversity over generations, among reproductive, immature, young, and seedling ontogenetic stages. Other studies comparing parents and progenies in the species Astrocaryum aculeatum (Ramos, Dequigiovanni, Sebbenn et al, 2016), Swietenia humilis (Rosas, Quesada, Lobo, & Sork, 2011), Copaifera langsdorffii , and Hymenaea courbaril (Carneiro et al, 2011) reported similar results to those obtained with E. precatoria.…”

“…Pollen flow, selfing, and pollen dispersal distance were also estimated assuming an exponential power dispersal Kernel (Austerlitz et al, 2004) with program NM+ (Chybicki & Burczyk, 2010), based on the neighborhood model (Burczyk, Adams, Moran, & Griffin, 2002). In this model, the distances of pollen dispersal and patterns were not derived from individual paternity assignments, as in the case of CERVUS, but indirectly from a spatially explicit mating model (Ramos, Dequigiovanni, Sebbenn et al, 2016). The model defines that the paternity of a progeny may result from: (a) self-fertilization with probability s; (b) pollen immigration from outside the plot, with probability m p ; or (c) crossing with a male located within the plot, with probability 1-s-m p (Burczyk et al, 2002).…”