Metrics details selective logging removes large trees that are often the main contributors to pollination We studied pollination patterns of the African mahogany We investigated two plots in Cameroon corresponding to three tree densities: unlogged forest (Ndama 2002) a mildly logged forest 1 year after logging (Ndama 2003) and a severely logged forest 30 years after logging (Dimako) We used four microsatellite markers to perform paternity analysis Selfing remained below 2% in all treatments Pollen flow was mainly long distance but with some proximity effects Average observed within-plot pollination distances were 338 and pollination by trees outside the plots was 70% (Ndama 2002) Despite sampling a limited number of seeds from a limited number of mother trees we obtained seeds sired by 35.6–38.3% of the potential within-plot pollen donors While trees 20 cm in diameter contributed to pollination results in Dimako suggest that individual larger trees contribute more to pollination than small ones This effect was not detected in the other treatments The results suggest extensive pollen flow in Sapelli the main limiting factor for regeneration after logging may be a reduction in the number of trees capable of producing seeds rather genetic effects due to limits to pollen dispersal Predicting the fate of genetic diversity of a timber tree species depends on our understanding of the consequences of logging on its reproductive biology Selective logging of large trees is a common form of harvesting in tropical forests; only trees large enough to reach a minimum diameter cutting limit (MDCL) are cut forest cover is globally maintained and timber is extracted along roads opened during harvesting operations and then abandoned the large trees harvested are also likely to have been the main contributors to reproduction both as seed producers and as pollen dispersers reducing reproductive tree density through selective logging may have drastic effects on gene flow and may increase selfing and correlated matings there is probably always a critical density of flowering trees in a forest below which pollination patterns are severely affected In view of this uncertainty about the response to natural or man-induced variation in density predictions about the consequences of selective logging on the reproductive biology of tropical trees are hazardous If timber harvesting reduces the number of pollinators per seed-bearing tree or increases selfing by delaying fertilization by allo-pollen then the genetic consequences should be easy to monitor Genetic relatedness within progenies is expected to increase as a consequence of increased selfing and/or decreased number of pollen donors levels of allelic and genetic diversity are predicted to show a stronger reduction between fruiting trees and their progenies after logging than before Analyses of paternity should also provide strong insights into the processes involved We explored the effect of density reduction due to logging on the reproductive biology of a tropical timber species Entandrophragma cylindricum Sprague (Meliaceae) commonly known by its trade name ‘Sapelli’ (1) Does mating occur preferentially between neighboring trees in Sapelli (2) Does moderate logging limit the number of potential fathers favored by proximity in such a way that seeds from a tree have reduced numbers of fathers (3) Does severe logging reduce the number trees that are close enough to get a proximity advantage and hence increase the diversity of male parents of the seed crop on a tree (4) Does low tree density result in increased selfing we studied Sapelli in two plots in Cameroon corresponding to three situations (which we henceforth term treatments): one plot before logging; the same plot 1 year after logging – to explore the impact of a limited reduction of density due to selective logging; and a low density plot logged several decades ago – to explore the long-term impact of low density we estimated the contribution of each mature tree to the fertilization of the seeds produced by focal trees by conducting an analysis of paternity We also assessed whether mating in Sapelli occurs preferentially between neighboring trees and whether large diameter trees are the main contributors to pollination In the continuous tropical forest cover of the Congo Basin trees are widely spaced and density is typically lower than five flowering individuals per hectare it is legal to selectively harvest Sapelli trees with a diameter at breast height (DBH) ⩾100 cm we considered that all trees with a diameter ⩾10 cm DBH were potential pollen donors as a conservative measure to ensure that all the trees that flowered within the plot had been genotyped Hence the trees at Dimako are expected to have grown by only 14 cm in DBH since logging The whole area around Dimako had been logged so we could monitor the effect of large-scale density reduction Both plots were part of the same continuous forest without any major physical barrier Densities of small Sapelli trees (10 cm⩽DBH<50 cm) were almost identical in the three treatments suggesting similar original global densities Densities of Sapelli trees (DBH⩾10 cm) per hectare in the three treatments were as follows: 1.52 in Ndama before logging (termed ‘Ndama 2002’) 1.13 in Ndama after logging (‘Ndama 2003’) and 0.28 in Dimako The average diameters of potential pollen donors were 93 Logging intensity was observed to be about 50% of legal-sized trees in Ndama 2002 and was probably much higher in Dimako as both densities and tree diameters were still very low We examined three subsets of individuals: (1) the whole population of mature trees termed ‘potential within-plot pollen donors’ from which we extracted (2) a sample of fruiting trees termed ‘mother trees’ and (3) the progenies of these ‘mother trees’ We sampled seeds under a series of fruiting trees at the end of the fruiting period in Ndama (in 2002 and in 2003) We selected a subset of focal mother trees They were chosen to be distributed haphazardly within the plot our goal was to obtain dispersed distribution of mothers within the plot so as to sample the pollen clouds in different areas An alternative would have been to choose individuals located at the center of the plots so as to increase the likelihood of identifying the father of seeds we would have reduced the independence of the estimates from different mothers Precision would have been at the expense of generality we tried to genotype equal numbers of seeds under each female parent we could analyze the relationship between size of a male tree its position relative to a focal mother tree and its contribution to the fertilization of seeds and this independently of female parent crop size ‘male success’ will refer to this estimate We wanted to highlight neighborhood effects rather that crop size variance effects Spatial analyses conducted a posteriori (see below for the methodology employed) showed that there were no significant difference in each treatment between the distribution of distances between all pairs of individuals and the distribution of distances between sampled mothers and potential within-plot pollen donors (P=0.089 in Ndama 2002 P=0.52 in Ndama 2003 and P=0.78 in Dimako) Seeds were collected under crowns of mother trees on the forest floor All sampled mother trees presented unique combinations of alleles so that we could establish that the ‘mother tree’ was a true parent Such seeds could either be seeds produced by the maternal tree or were seeds from a neighboring tree sired by pollen from the ‘maternal tree’ Only very few seeds (less than 5%) were not the offspring of the putative mother This feature demonstrates that most of the times the putative mother tree was effectively the mother tree many more cases of genotype discrepancy would have been detected We retained for further analysis only the mothers for which ⩾ 10 seeds were genotyped without ambiguity and seeds were then ground to powder in liquid nitrogen The solution (24 μl total volume) contained 0.4 μl of the four dNTPs (100 μ M) 4.8 μl of 10 × reaction buffer (750 mM Tris–HCl 5.5 μl of mix of the four primer couples (10 μ M) 0.4 μl (2 units) of Taq DNA polymerase (Eurogentec Red GoldStar One primer from each pair was dye labeled; colors of labels were chosen according to marker size range and did not overlap Cycling conditions were: denaturing initialized at 94°C for 4 min 30 s at the annealing temperature of 55°C and 1 min at 72°C with a final extension step of 10 min at 72°C PCRs were conducted using a PTC100 thermocycler (MJ Research A total of 2 μl of PCR products were pooled in 15 μl of deionized formamide and 0.2 μl of GeneScan-500XLROX size standard and analyzed on an ABI Prism 310 Genetic Analyser (Perkin Elmer Size of each fragment was determined using the GeneScan program (Applied Biosystems Analyses led to three situations: no father identified inside the plot a single father inside the plot or two or more fathers within the plot among which we were not able to discriminate We first estimated the percentage of pollination events originating from outside the plot (GFO gene flow from outside) for each mother sampled and averaged those values to obtain an estimate for the entire plot GFO is given as the percentage of each mother's progeny for which no pollen donor was identified inside the plot We used Spearman's nonparametric rank correlation test to detect whether GFO decreased with distance of the mother tree from the closest edge of the plot (one-tailed test) We then discarded the few seeds for which two or more potential fathers were found and used only seeds for which a single father was identified (called a ‘known within-plot pollen donor’) this category comprised more than 90% of the total number of seeds for which at least one potential father was identified within the plot When a single flowering tree was identified as the father of several seeds from a given mother we considered this to represent several independent mating events We computed the percentage of known within-plot pollen donors among the potential within-plot pollen donors the average DBH of known within-plot pollen donors and the distributions of DBH We estimated the observed within-plot male mating success (MMSj) of each known pollen donor j as follows: where ni is the total number of mother trees the observed number of seeds of mother i fertilized by pollen donor j that is the average number of seeds sampled under mother trees in that treatment; and SEi the sampling effort for mother tree i that is the number of seeds sampled from this particular mother We averaged the MMSj to obtain the MMS at the plot level Distribution of MMS values in Ndama 2002 was compared to the distributions in Ndama 2003 and Dimako using Kolmogorov–Smirnov tests To detect whether larger trees were more likely to contribute to pollination than smaller trees the DBH distributions of effective and potential pollen donors using Kolmogorov–Smirnov tests To test whether tree density and size distribution affected which size classes contributed to pollination the DBH distribution of known pollen donors observed in Ndama 2002 was compared to those of Ndama 2003 and Dimako among within-plot successful pollen donors large trees fertilized more seeds than small trees we compared the distribution of MMS values among the five DBH size class: DBH<50 cm we established which differences among size classes contributed most to this significance by calculating pair-wise Mann–Whitney tests we compared MMS values among treatment for each DBH class using a Kruskal–Wallis test and when significant we applied Mann–Whitney tests We tested for directionality of pollen flow using Kolmogorov–Smirnov tests we determined the angle (relative to north) from each effective and each potential within-plot pollen donor to that tree We then divided angles into classes (15 degarc) and compared distributions of angles between known within-plot pollen donors and mother trees and between potential within-plot pollen donors and mother trees We used Kolmogorov–Smirnov tests to compare the distribution of pollination distances between Ndama 2002 and Ndama 2003 As the plot in Dimako was four times larger than the one at Ndama we repeated the procedure without taking into account pollination distances above 1397 m Kinship values were computed in each treatment for each progeny family using as allelic frequencies of the reference population those issued from the whole progeny sample Kinship values were averaged in each treatment among progeny families to obtain a mean estimate at the plot level We used Kolmogorov–Smirnov tests to compare the distributions of the kinship values among progeny families between Ndama 2002 and Ndama 2003 We tested differences between He and Fis values among the different subsets using Fstat Symbols show tree location (triangles=potential pollen donors DBH<50 cm (this last class of trees were only plotted on the Dimako map); empty triangles potential pollen donors not identified as effective ones; filled triangles or filled circles (for mothers) identified effective pollen donor (known pollen donor); empty circles mothers not identified as pollen donors; arrows Individual GFO rate is given for each mother close to its location The estimated percentage of self-pollination was lower than 2% in all three treatments (Table 1) and did not differ significantly among treatments In Ndama 2003 and Dimako some trees (20 cm in DBH) were recorded as effective pollen donors Of the potential within-plot pollen donors 38.3 and 36.4% were identified as known pollen donors in Ndama 2002 Average numbers of seeds sired by individual within-plot known pollen donors were 1.47 Individual MMS values tended to increase with decreasing density values from Ndama 2002 to Ndama 2003 and to Dimako but were only significantly different between Ndama 2002 and Dimako (P<0.001) MMS and DBH distributions of potential and known pollen donors DBH distributions of potential pollen donors (white bar) plotted with the DBH distributions of known pollen donors (gray bar) median values of the MMS of effective pollen donors (MMS) per diameter class (see text for computing details) Note that the density of small trees (DBH<50 cm) is equivalent in the three treatments but the numbers are different because the Dimako plot is 4.4 times larger than the Ndama plot The Kruskal–Wallis tests within treatment showed that MMS values per size class differed only within the Dimako treatment; MMS values in DBH size class (100–119) were higher than in all smaller size classes (class <50 P=0.036) and MMS values in size class (50–79) were higher than in DBH size class <50 cm (P=0.025) MMS within size class were heterogeneous among treatments for size classes (100–119) and >120 cm (Kruskal–Wallis respectively P=0.002 and P=0.046) MMS were higher in Dimako than in Ndama 2002 for DBH size classes (100–119) (P=0.006) and ⩾120 cm (P=0.036) and higher in Dimako than in Ndama 2003 for DBH size class (100–119) (P=0.006) We detected no significant directionality in pollen flow in any of the three treatments (P=0.091 Distributions of distances between all individuals and between sampled mothers and potential and known pollen donors (pollination distances) ⩾ Distributions of pair-wise distances between all individuals (a- distributions of pair-wise distances between sampled mothers and potential pollen donors (b- h-) and distributions of pair-wise distances between sampled mothers and known pollen donors Class size (under each boxplot) and values of the means (in bold) are reported The distributions of observed within-plot pollination distances differed significantly between Ndama 2002 and Ndama 2003 (P=0.037) but not between Ndama 2002 and Dimako The multilocus estimates of outcrossing rates (tm) were 0.98 in the three treatments, while single-locus estimates of outcrossing rate (ts) were 0.96 and were significantly different from the multilocus estimates (Table 1) estimates of biparental inbreeding (difference tm–ts) were low in the three treatments (tm–ts⩽0.025) but consistent and significant Distributions of kinship coefficient values among progeny families were not significantly different between Ndama 2002 and Ndama 2003 Genetic diversity parameters for the three treatments are reported in Table 2 We only found a slight but significant difference between values of the standardized allelic richness (A) between within-plot potential pollen donors and progenies in Dimako (P<0.05) but not between known within-plot pollen donors and progenies in any of the three treatments The estimates of gene diversity among the different subsets were not significantly different within each treatment He was high in the three treatments and in all the subsets (He>0.9) while the lowest values of He were found in the progeny subsets in each treatment (He=0.917 Significant but low deficits in heterozygotes were found in all progeny subsets (Ndama 2002 and in the potential pollen donors subset of Dimako (Fis=0.020 The mother trees in Ndama 2003 presented an excess of heterozygosity (Fis=−0.062 paternity analysis demonstrated that trees 20 cm in DBH did contribute to pollination Hence genotyping ambiguities cannot explain our high GFO values: relatively long-distance gene flow is frequent in Sapelli There is not a very strong mating advantage to neighboring plants we observed long-distance pollination within plots Hence extensive pollen flow is frequent in tropical trees about one-third of the potential within-plot pollen donors were identified as being effective (35.6 This is a high proportion when taking into account numbers of seeds analyzed and numbers of potential parents within the plots although MMS has generally been found to be high in most species each recognized male parent sired on average only 1.47 2.33 and 2.66 of the genotyped seeds in Nadama 2002 Increasing sample size would probably have substantially increased the number of effective parents This suggests that many more than one-third of adult trees produce male flowers every year; hence male flowering differs from female flowering and fruit set analyzing two sets of large Sapelli trees (DBH⩾50 cm n≈50) in the same locations (Ndama and Dimako) in 1998 and 1999 only one-third of all trees set seeds (unpublished data) As expected from the numerous observed within-plot pollen donors kinship within progeny families did not differ among treatments and values of both allelic (A) and genetic (He) diversity in progenies did not differ from those observed in within-plot pollen donors and mother trees We conclude from these results that despite the flowering-tree density reduction caused by logging genetic diversity in these populations of Sapelli is not endangered The extensive pollen flow has sustained the genetic variation we may assume that even in the low-density treatment limiting pollen would probably have resulted in increased kinship within progeny families as a result of pollination by a restricted pool of pollen donors Despite the observed long-distance gene flow Closely nearby trees were more likely to have pollinated a mother tree While median within-plot detected pollination distances were 260 the median distance to potential pollen donors were 493 Further GFO decreased or tended to decrease with distance from the edge of the plot as the GFO rate observed in each treatment showed that more than half of the known pollen donors were situated outside the plot (66–74%) true average pollination distances in Sapelli are much larger The significant reduction of observed within-plot pollination distances between Ndama 2002 and Ndama 2003 and the lack of difference between Ndama 2002 and Dimako could be explained by a two-step process in which close neighbors are more favored at intermediate densities but when density becomes even lower there are no more close neighbors pollination by within-plot neighbors never accounted for more than about one-third of pollination While there was a slight tendency for mother trees to be heterozygotes we observed a low (<4%) but consistent deficit in heterozygotes in all progenies This deficit indicates minor but significant biparental inbreeding and correlated mating which could be explained by the slight spatial structuring Indeed limited seed dispersal (almost all seeds collected close to a mother tree effectively came from that tree) associated with some pollination by nearby trees may be sufficient to have generated such a structuring that this pattern could be explained by selection against even slight inbreeding during the growth of seedlings to seed-producing size In Ndama, we did not detect any effect of tree size on male reproductive success, but there was a striking one in Dimako. In Dimako, the size distribution of trees was biased toward small trees (Figure 2c) This resulted in a stronger contribution of small trees to pollination than in Ndama the large trees (size class (100–119) cm) in DBH were overrepresented among the known within-plot pollen donors and each known within-plot pollen donor of that size contributed to the fertilization of more seeds This suggests that (1) large trees are more efficient pollen donors than smaller ones competition among large trees reduces their average success and (3) numbers of seeds sampled and number of small trees were not sufficient to detect whether small trees are less efficient pollen donors Nevertheless the result depends on a single treatment there are not enough representatives of each size class to test for whether results could alternatively be explained by the spatial disposition of the trees We conclude that pollination of Sapelli is a mix of local and long-distance pollen flow Long-distance pollen is sufficiently prevalent to have a strong homogenizing effect on the regional gene pool in the diffuse Sapelli populations whatever the local densities of flowering individuals reduced densities after logging resulted in a dramatic increase in selfing predicting the consequences of logging policies and regulations requires genetic studies on the species in question La flore forestière de la Cote d’Ivoire Publication no Plant pollinator interaction in tropical rain forests genetic differentiation and speciation in tropical rain forest plants Controlling the false discovery rate – a practical and powerful approach to multiple testing Microsatellite primer amplification by multiplexing: a first application to Eucalyptus grandis Effects of habitat fragmentation on the reproductive ecology of four plant species in mallee woodland Simple sequence repeats provide a direct estimate of pollen-mediated gene dispersal in the tropical tree Gliricidia sepium Population structure delineated with microsatellite markers in fragmented populations of a tropical tree Carapa guianensis (Meliaceae) L’analyse des cernes : applications aux études de croissance de quelques essences en peuplements naturels de forêt dense africaine; Mating system of Carapa procera (Meliaceae) in the French Guiana tropical forest Diamètre de fructification de quelques essences en forêt naturelle centrafricaine Evidence of low gene flow in a neotropical clustered tree species in two rainforest stands of French Guiana High level of genetic differentiation for allelic richness among populations of the argan tree (Agrania spinosa (L) Skeels) endemic to Morocco Genotyping of mature trees of Entandrophragma cylindricum with microsatellites FaMoz: a software for parentage analysis using dominant codominant and uniparentally inherited markers Comparison of microsatellites and amplified fragment length polymorphism markers for parentage analysis Disturbance-induced density-dependent seed set in Shorea siamensis (Dipterocarpaceae) a tropical forest tree FSTAT (Version 12): a computer program to calculate F-statistics Classification and ecology of closed-canopy forest in Ghana Effect of forest fragmentation on genetic diversity and mating system in a tropical tree Pithecellobium elegans The breeding structure of tropical tree populations SPAGEDi: a versatile computer program to analyse spatial genetic structure at the individual or population levels Ecological profiles of Ghanaian forest trees Viability selection at three early life stages of the tropical tree Pollen-mediated gene flow and differential male reproductive success in a tropical pioneer tree Cecropia obtusifolia Bertol (Moraceae): a paternity analysis Variation in pollen dispersal between years with different pollination conditions in a tropical emergent tree Estimation of outcrossing rate on Dryobalanops aromatica Gaernt F in primary and secondary forests in Brunei Borneo Southeast Asia Long-distance pollen flow and tolerance to selfing in a neotropical tree species Mating system parameters of Dryobalanops aromatica Gaertn f (Dipterocarpaceae) in three different forest types and a seed orchard Mating system parameters in a tropical tree species Shorea leprosula Miq (Dipterocarpaceae) from Malaysian lowland dipterocarp forest Spatial genetic structure of a tropical understory shrub Isozyme variation in tropical trees: patterns of genetic organization Statistical confidence for likelihood-based paternity inference in natural populations The effect of the density of flowering individuals on the mating systems of nine tropical tree species Microsatellite analysis of the breeding system and seed dispersal in Shorea leprosula (Dipterocarpaceae) Reproductive and genetic consequences of forest fragmentation: two case studies of neotropical canopy trees Genetic diversity and outcrossing rate between undisturbed and selectively logged forests of Shorea curtisii (Dipterocarpaceae) using microsatellite DNA analysis GENEPOP (version 12): population genetics software for exact tests and ecumenicism Extensions of models for the estimation of mating systems using n independent loci Pollen dispersal in low-density populations of three neotropical tree species The flower biology of the Meliaceae and its bearing on tree breeding Cytology and reproductive biology of Meliaceae A review of outcrossing and pollen-mediated gene flow in neotropical trees Increased pollen flow counteracts fragmentation in a tropical dry forest: an example from Swietenia humilis Zuccarini Download references We are grateful to A Mbenda and the field workers for help in collecting material in the field M-P Dubois and C Debain for help in the laboratory work S Gerber for helpful comments on the paternity analysis P Jarne and D McKey for comments on the manuscript This work was supported by funds from Cirad (Centre de Coopération Internationale en Recherche Agronomique pour le Développement) This paper is dedicated to late Caroline Dubois who started the field observations on the sites This paper is part of the PhD of Mathieu Lourmas at the University of Montpellier on the impact of human activities on population genetics and conservation biology of Entandrophragma cylindricum in the Congo Basin The authors are participating in several projects that aim at understanding genetic population processes in tropical trees and apply these results to their conservation Download citation DOI: https://doi.org/10.1038/sj.hdy.6800976 Anyone you share the following link with will be able to read this content: a shareable link is not currently available for this article the charity association of the First Lady also offered diverse gifts to the population in the locality on Saturday Наслаждайтесь азартом на любом устройстве! Скачайте мобильное приложение Vavada kz и играйте без блокировок Начните с приветственного бонуса и открывайте для себя турниры Offer your company and your employees the best information Take advantage of our preferential rates reserved for professionals Discover our digital subscription offers to find Cameroon-Tribune at home Statistics from Doume Health District in the East Region show that greater awareness and the offer of motorbike ambulances by UNFPA have enabled more rural women to be promptly transported to health facilities for safe delivery According to the last Cameroon Demographic and Health Survey and the 2014 Multi-indicator Cluster Survey Statistics about 7,000 women die in the country due to pregnancy complications or during delivery While neonatal mortality (the death rate of babies in the first 28 days of life) was 28 deaths per 1,000 live births with the support of the United Nations Children’s Fund UNICEF and the United Nations Population Fund the project is funded by the Islamic Development Bank It covers 34 health districts in the Far North East and South Regions - the most vulnerable in the country which comprises three administrative subdivisions in Upper Nyong Division (Doume The health district counts 132 communities and a population of 55,000 Two years into the implementation of the project in Doume Health District says a 100 per cent increase was recently recorded in vaccination and antenatal clinic attendance This followed sensitisation campaigns for people to continue to patronise orthodox health services – despite the Coronavirus pandemic The awareness campaigns were led by Multitask Community Health Workers and volunteers of the Ministry of Youth Affairs and Civic Education the number of births in health facilities in Doume Health District shot up from 25 per cent two years ago to 55 per cent and this happened at home where she gave birth there were three newborn deaths – two in hospital and one at home The ones who died in hospital were brought in late we recorded between 15-28 declared deaths of children and 5-6 maternal deaths a year,” the District Medical Officer notes with a feeling of “work well done!”