Research Article Contemporary pollen and seed dispersal in natural populations of Bertholletia excelsa (Bonpl.).

Abstract

ABSTRACT. Due to the nutritional content and commercial value of its seeds, Bertholletia excelsa is one of the most important species exploited in the Amazon region. The species is hermaphroditic, insect pollinated, and its seeds are dispersed by barochory and animals. Because the fruit set is dependent on natural pollinator activity, gene flow plays a key role in fruit production. However, to date, there have been no studies on pollen and seed flow in natural populations of B. excelsa. Herein, we used microsatellite loci and parentage analysis to investigate the spatial genetic structure (SGS), realized pollen and seed dispersal, and effective pollen dispersal for two B. excelsa populations in the Brazilian Amazon forest. Two plots were established in natural forests from which adults, juveniles, and seeds were sampled. Realized and effective pollen flow was greater than realized seed flow. The distance of realized pollen dispersal ranged from 36 to 2060 m, and the distance of realized seed dispersal ranged from 30 to 1742 m. Both pollen and seeds showed a dispersal pattern of isolation by distance, indicating a high frequency of mating among near-neighbor trees and seed dispersal near to mother trees. Both populations present SGS up to 175 m, which can be explained by isolation by distance pollen and seed dispersal patterns. Our results suggested that fragmentation of these forest populations may result in a significant decrease in gene flow, due to the isolation by distance pollen and seed dispersal patterns.

Research Article Hierarchical outcrossing among and within fruits in Bertholletia excelsa Bonpl. (Lecythidaceae) open-pollinated seeds

“…Therefore, B. excelsa overall produces seeds through outcrossing; however, there are some variations between tree and fruits within trees, due to individual variations in self-incompatibility or due inbreeding depression; thus, same trees may produce seeds from self-fertilization. The species presents floral structure capable of precluding self-fertilization (O'Malley et al, 1988;Maués, 2002;Cavalcante, 2008), although self-fertilization at population level (at range 0.85 to 0.98) and at individual level (at range 0.90 to 0.98) have been reported in other studies (O'Malley et al, 1988;Baldoni et al, 2017). These results suggest that the species presents latent self-incompatibility; some Table 3.…”

“…Bertholletia excelsa Bonpl. (Lecythidaceae), popularly known as Brazil nut, presents seeds with high commercial and nutritional value (Wadt et al, 2015;Baldoni et al, 2017). Brazil nut (NTFP) extraction favors forest preservation; therefore, it is considered a model species for conservation if one also takes into account that wood cutting is prohibited by law (Wadt et al, 2005).…”

“…Reis et al (2009) developed 12 polymorphic microsatellite markers to the species and Sujii et al (2013) developed another 12. In addition, genetic studies with molecular markers in fragmented forests using natural seeds or regenerates helped evidencing processes such as genetic drift, gene flow, selection and mating system (Carvalho et al, 2010;Wadt et al, 2015;Baldoni et al, 2017).…”

“…Knowing the mating system of a tree species is important for genetic conservation, tree breeding and environmental reforestation, since fertilization patterns determine the relatedness and inbreeding of next generations and, consequently, the effective size of seed collection (Sebbenn 2006). The mating system of B. excelsa has been investigated (O'Malley et al 1988, as well as its pollen dispersal patterns (Baldoni et al 2017). These studies have been investigating the outcrossing rates, the mating between related trees, the paternity correlation among and within fruit variations, and pollen-dispersal distance and patterns.…”

Production of Bertholletia excelsa Humb. & Bonpl., (Lecythidaceae) seedlings in microenvironments under different substrates

“…This species promotes employment and income for thousands of workers through the trade and local consumption of its seeds (Tonini, 2011;Scoles et al, 2016;Costa et al, 2017). B. excelsa seeds present high commercial and nutritional value and are internationally traded as the Brazil nut denomination (Wadt et al, 2015;Baldoni et al, 2017;Wadt et al, 2018).…”