Seed and pollen dispersal and fine-scale spatial genetic structure of a threatened tree species: Pericopsis elata (HARMS) Meeuwen (Fabaceae)

Abstract

Seed and pollen dispersal are important for defining sustainable forest management practices. By reducing population density, selective logging could affect not only the seed production of timber species but also the selfing rate and the patterns of seed and pollen rains. To assess these risks, we characterized seed and pollen dispersal patterns and the fine-scale spatial genetic structure (FSGS) of Pericopsis elata, a gregarious, wind-dispersed legume tree which is highly logged in Central Africa and threatened by overexploitation. Eleven microsatellite markers were used to genotype 189 adults and 664 seedlings in a 4 km 2 plot in the Democratic Republic of Congo (DRC). According to the neighbourhood model, seed dispersal was extremely leptokurtic, with 80% of seeds dispersal distances <75 m, 15% >500 m. Pollen dispersal was locally more extensive (median distance 260 m), but pollen immigration was not detected, and the selfing rate (54%) appeared particularly high compared to other tropical tree species. Limited gene dispersal resulted in remarkably high FSGS (S p = 0.072). A decay of inbreeding with age also suggests that the species is prone to inbreeding depression. The reproductive success of trees was positively related to their diameter at breast height (dbh), with half of the progeny mothered by trees with dbh > 97 cm and fathered by trees with dbh > 119 cm. Our study highlights that (1) seed sources must be diversified for plantation or population reinforcement to limit consanguinity, and (2) the legal minimum cutting diameter in DRC (60 cm) should be increased to maintain enough post-logging reproductive potential.

Inbreeding depression affects the growth of seedlings of an African timber species with a mixed mating reproductive system, Pericopsis elata (Harms) Meeuwen

“…However, there are exceptions, with some species having a truly mixed-mating system, like some Eucalyptus species (Byrne et al 2008). In tropical Africa, a notable exception is Pericopsis elata (Harms) Meeuwen, a large legume tree from the dense forests, in which a selfing rate of 55% has been measured in seeds and young seedlings in a population from DRC (Angbonda et al, 2021). In the studied population, the proportion of selfed adults dropped to about 26%, probably reflecting the impact of ID on survival rate.…”

Development and characterization of microsatellite markers in the African timber tree species Cylicodiscus gabunensis (Fabaceae)

“…Nuclear simple sequence repeat markers (SSR), or microsatellites, have gained considerable importance in plant genetics because of their high level of transferability to related species, co-dominant inheritance, important genome coverage, high polymorphism and amenability to high-throughput genotyping [11]. They are used to study the mating system, gene flow, inbreeding depression and the determinants of reproductive success through parentage analyses, for example in African trees [12][13][14]. They are also used to study the genetic structure of populations, phylogeographic patterns and other studies of genetic variation [8,14].…”

“…They are used to study the mating system, gene flow, inbreeding depression and the determinants of reproductive success through parentage analyses, for example in African trees [12][13][14]. They are also used to study the genetic structure of populations, phylogeographic patterns and other studies of genetic variation [8,14]. The natural regeneration deficit and low observed densities of C. gabunensis in dense forest suggest that special precautions should be taken to achieve sustainable exploitation of this species [2,5].…”

Development and characterization of microsatellite markers in the African timber tree species Cylicodiscus gabunensis (Fabaceae)

“…Nuclear simple sequence repeat markers (SSR), or microsatellites, have gained considerable importance in plant genetics because of their high level of transferability to related species, co-dominant inheritance, important genome coverage, high polymorphism and amenability to high-throughput genotyping [11]. They are used to study the mating system, gene flow, inbreeding depression and the determinants of reproductive success through parentage analyses, for example in African trees [12][13][14]. They are also used to study the genetic structure of populations, phylogeographic patterns and other studies of genetic variation [8,14].…”

“…They are used to study the mating system, gene flow, inbreeding depression and the determinants of reproductive success through parentage analyses, for example in African trees [12][13][14]. They are also used to study the genetic structure of populations, phylogeographic patterns and other studies of genetic variation [8,14]. The natural regeneration deficit and low observed densities of C. gabunensis in dense forest suggest that special precautions should be taken to achieve sustainable exploitation of this species [2,5].…”