Long‐pollen Movement and Deviation of Random Mating in a Low‐density Continuous Population of a Tropical Tree Hymenaea courbaril in the Brazilian Amazon

Abstract

Mating system and pollen flow are two key elements to understand the genetic structure of tree species. Mating and pollen‐dispersal patterns of a low‐density population of bat pollinated Hymanea courbaril were examined before logging in a 546‐ha plot in the Brazilian Amazon. The multilocus genotypes of nine microsatellite loci were determined for 130 adult‐trees and 367 seeds collected from 20 seed‐trees. Mating system analysis, using mixed‐mating model and paternity analysis showed that the studied population is perfectly outcrossed (tm= 1.002), and probably self‐incompatible. However, significant deviations from random mating were detected for mating among relatives (tm−ts= 0.096, P < 0.05) and correlated matings (rp= 0.289, P < 0.05), indicating inbreeding in the population and that part of offspring are full‐sibs (28.9%). Inbreeding was reflected in the positive and significant fixation index observed in adult trees (F= 0.137, P < 0.05), although no significant inbreeding was detected in offspring (F= 0.074, P > 0.05). The effective number of pollen donors mating with each seed‐tree was determined to be low (Nep≈ 4). The average of pollen flow distance was measured inside of the plot by both paternity (827 ± 429 m) and TwoGener analysis (115–363 m). However, this underestimated pollen dispersal distance, since the detected rate of pollen immigration inside of the plot was high (55%). The observed long‐pollen dispersal distance is probably related to pollination by bats and the low density of reproductive trees in the site.

Effect of selective logging on genetic diversity and gene flow in Cariniana legalis sampled from a cacao agroforestry system

“…The pollen immigration from outside the sampled farm may represent a contribution of pollen and seeds for 63.16% of seedlings sampled, suggesting long distance gene flow of pollen and/or seeds. The observed long distance pollen dispersal found in this study agrees with the observations in other species of tropical trees of low population density, thereby suggesting that the average distance of pollen dispersal is generally greater than 200 m (Nason and Hamrick, 1997;White et al, 2002;Gaiotto et al, 2003;Dick et al, 2003;Carneiro et al, 2007;Cloutier et al, 2007;Eduardo et al, 2008). The agroforestry system to which the population of C. legalis is found most likely favors the action of pollen and seed dispersers.…”

Microsatellite diversity and effective population size in a germplasm bank of Hymenaea courbaril var. stilbocarpa (Leguminosae), an endangered tropical tree: recommendations for conservation

“…Bawa (1974) and Jansen (1983) report this species to be self-incompatible. Studies by Dunphy et al (2004) and Lacerda et al (2008a) use genetic markers to demonstrate that H. courbaril is perfectly outcrossed, confirming the results of Bawa (1974) and Jansen (1983). According to Gibbs et al (1999), this apparent incompatibility may result from post-pollination events.…”

“…The fruits and resin are also commercially important products, with the latter exploited in Brazil for use in varnish, incense and folk medicine (Lee and Langenheim 1975). The dimensions reached by the typical forest species (height and diameter), combined with the good physical features of the timber, make this species one of the most valuable and most intensively exploited wood species in the Brazilian Amazon (Lacerda et al 2008a). …”

“…Although the species has such a wide distribution, it generally occurs in a low-density population (\1 tree/ha). Individual size varies markedly and is directly related to the habitat occupied: populations that grow in tropical forests can reach heights of 65 m, while those in the Cerrado and semiarid forests reach a height of just a few meters (Lacerda et al 2008a). H. courbaril is a diploid (n = 12) species with alternated leaves, bifoliolate and shortly petiolate; it is hermaphroditic with inflorescences composed of a few racemes; the fruits are indehiscent pods 5-12 cm long and 3-5 cm wide with a thick, floury and sweet endocarp Langenheim 1974, 1975;Cowan and Polhill 1981;Leite 2007).…”

Dipteryx alata Vogel (Fabaceae) a neotropical tree with high level of selfing: implication for conservation and breeding programs

“…The 95% confidence interval for each estimate was (1 -r p )), full-sibs (P fs = t 2 m r p ), and self-half-sibs (P shs = 2st m ), mean coancestry coefficient (Θ), and variance effective size (N e ) as described in Tambarussi et al (2016). The number of seed trees necessary for seed collection to retain a reference effective population size (N e(r) ) of 150 (Lacerda et al 2008) was calculated as: M = N e(r) /N e (Sebbenn 2006). The estimate of m is based on three assumptions: (i) seed trees are not related, (ii) seed trees do not receive an overlapping pollen pool (each seed tree mates with a different set of pollen donors) and (iii) seed trees do not mate with each other.…”