Fine-scale spatial genetic structure of Dalbergia nigra (Fabaceae), a threatened and endemic tree of the Brazilian Atlantic Forest

Abstract

The Atlantic Forest is one of the most diverse ecosystems in the world and considered a hotspot of biodiversity conservation. Dalbergia nigra (Fabaceae) is a tree endemic to the Brazilian Atlantic Forest, and has become threatened due to overexploitation of its valuable timber. In the present study, we analyzed the genetic diversity and fine-scale spatial genetic structure of D. nigra in an area of primary forest of a large reserve. All adult individuals (N = 112) were sampled in a 9.3 ha plot, and genotyped for microsatellite loci. Our results indicated high diversity with a mean of 8.6 alleles per locus, and expected heterozygosity equal to 0.74. The co-ancestry coefficients were significant for distances among trees up to 80 m. The Sp value was equal to 0.017 and indirect estimates of gene dispersal distances ranged from 89 to 144 m. No strong evidence of bottleneck or effects of human-disturbance was found. This study highlights that long-term efforts to protect a large area of Atlantic Forest have been effective towards maintaining the genetic diversity of D. nigra. The results of this study are important towards providing a guide for seed collection for ex-situ conservation and reforestation programmes of this threatened species.

Genetic diversity in natural populations of Stylosanthes scabra using ISSR markers

“…The majority part of genetic variation (60%) was distributed among populations and 40% was distributed within populations, according to the AMOVA results. The species with autofecudation exhibit greater genetic diversity among the populations (Buzatti et al, 2012), whereas this is different for the plants with high rates of alogamy. In a study by Santos-Garcia et al (2012) with microsatellite markers, S. capitata (which may present alogamia above 20%) did not present a correlation between the genetic distance and the collection sites, although few accesses by collection site were considered by these authors.…”

Research Article Genetic diversity in natural populations of <i>Stylosanthes</i> <i>scabra</i> Fabaceae using ISSR markers

“…Most of the genetic variation (60%) was among populations and 40% within populations, according to the AMOVA results. Species with auto fecundation exhibit greater genetic diversity among populations (Buzatti et al, 2012), which does not happen for plants with high rates of allogamy. A study by Santos Garcia et al (2012) with microsatellite markers, S. capitata (which may present allogamy above 20%) did not show a correlation between the genetic distance and the collection sites, although these authors examined few samples per collection site.…”

Demographic history and spatial genetic structure in a remnant population of the subtropical tree Anadenanthera colubrina var. cebil (Griseb.) Altschul (Fabaceae)

“…These inbreeding coefficients are substantially higher than those displayed by other insect- N, number of individuals sampled; F 1 , pairwise kinship in the first distance class (up to 10 m); b, regression slope of pairwise kinship with the logarithm of distance; Sp, Sp statistic (see text). Values followed by *** were statistically different from zero (p < 0.001); standard error (SE) is indicated in parentheses pollinated forest tree species such as Dalbergia nigra (F IS = 0.08), which is mainly pollinated by bees (Buzatti et al 2012), Cabralea canjerana (F IS = 0.06) pollinated by moths (de Oliveira Melo et al 2014), or Prunus africana (F IS = 0.08-0.19), whose main pollinators are Hymenoptera and Diptera (Berens et al 2014). Previous studies have also revealed a heterozygote deficit in A. colubrina var.…”

“…The knowledge of spatial patterns of genetic diversity is fundamental for the conservation of native forest tree species since it can inform the design of conservation strategies (Frankham 2003;Escudero et al 2003;Davies et al 2013). Fine-scale spatial genetic structure (FSGS), defined broadly as the non-random spatial distribution of genotypes, has been described in many plant populations (see reviews in Vekemans and Hardy 2004;Troupin et al 2006;Hardy et al 2006;Dick et al 2008;Buzatti et al 2012;Berens et al 2014;Ewédjè et al 2017). FSGS is shaped by the complex interplay of microevolutionary processes (i.e., genetic drift, gene flow, and natural selection) and mating system (Epperson 2003;Dick et al 2008).…”