The effect of population density on gene flow between adult trees and the seedling bank in Abies alba Mill.

Abstract

Populations of smaller effective sizes or subjected to strong environmental filtering have a higher risk of stochastic changes in their genetic properties. This study tested the hypothesis that reducing the density of parent trees combined with environmental filtering during the stage of regeneration establishment affects gene flow between the parent and offspring populations of Abies alba Mill. The genetic variation and spatial genetic structure of parent trees and seedlings were compared in the Western Carpathians (southern Poland) in 27 stands with varying adult tree and regeneration densities. The analysis comprised 1592 individuals and was based on five nuclear microsatellite markers. The proportion of stands with significant spatial genetic structure in the adult tree and seedling cohorts increased as the density of adult trees decreased. The genetic differentiation between adult trees and seedlings expressed by the fixation index F ST was between 0.005 and 0.021 and increased as the density of adult trees decreased but was not correlated with the seedling abundance. At the within-stand level, the analysis revealed shifts in the average number of alleles per locus (between − 15% and + 28%), the observed heterozygosity (between − 25% and + 20%) and expected heterozygosity (between − 8% and + 11%) between the populations of adult trees and seedlings. It was concluded that in mixed stands with densities of A. alba trees about 50 adult individuals per ha, there may be some risk of reduced effective population size and disturbed vertical gene flow, but significant shifts in the level of genetic variation are less likely.

Fine‐scale spatial genetic structure across the species range reflects recent colonization of high elevation habitats in silver fir (Abies albaMill.)

“…We found that silver fir was characterized by a moderate and significant FSGS at most parts of the species range (Figure 2 , Table 2 ). Among the previous studies of FSGS in silver fir, Sagnard et al ( 2011 ) and Leonarduzzi et al ( 2016 ) found a weak or absent FSGS in French and Central Italian populations, respectively, while a relatively strong FSGS was reported from populations from the Italian Alps (Mosca et al, 2018 ) and the Western Carpathians (Paluch et al, 2019 ). Based on our results together with the above mentioned studies, Sp in silver fir ranges from 0 to 0.013 with a global mean Sp of 0.005 (CI95% [–0.001, 0.01]).…”

“…The level of polymorphism in genetic markers can also vary across the species range, and influence the power of a data set for estimating kinship (Wang, 2016 ) or the spatial correlograms. The same genetic data that are used to estimate the spatial autocorrelation of allele frequencies may also be used to partially reconstruct the pedigree, which can be used to understand the mechanisms that maintain FSGS, such as the unequal reproductive success among individuals (e.g., Gerzabek et al, 2017 ; Oddou‐Muratorio et al, 2018 ; Paluch et al, 2019 ) or sex specific dispersal dynamics (Aguillon et al, 2017 ).…”

Fine-scale spatial genetic structure across the species range reflects recent colonization of high elevation habitats in silver fir (Abies albaMill.)

“…We found that silver fir was characterized by a moderate and significant FSGS at most parts of the species range (Figure 2, Table 2). Among the previous studies of FSGS in silver fir, Sagnard et al (2011) and Leonarduzzi et al (2016) found a weak or absent FSGS in French and Central Italian populations, respectively, while a relatively strong FSGS was reported from populations from the Italian Alps (Mosca et al, 2018) and the Western Carpathians (Paluch et al, 2019). Based on our results together with the above mentioned studies, Sp in silver fir ranges from 0 to 0.013 with a global mean Sp of 0.005 (CI95% [-0.001, 0.01]).…”

“…The same genetic data that are used to estimate the spatial autocorrelation of allele frequencies may also be used to partially reconstruct the pedigree, which can be used to understand the mechanisms that maintain FSGS, such as the unequal reproductive success among individuals (e.g. Gerzabek et al, 2017;Oddou-Muratorio et al, 2018;Paluch et al, 2019) or sex specific dispersal dynamics (Aguillon et al, 2017).…”

Spatial genetic structure and seed quality of a southernmost Abies nephrolepis population

“…Hambaeksan was not significant and the estimated Sp value (0.0036) was relatively weak compared to the average of outcrossing species (0.0126) or wind-dispersed species (0.0064) 39 . However, it was akin to Sp values of other species in Abies 40 , 41 , 42 . While there was no significant SGS in ST, BT had a stronger SGS.…”