Distribution and fine-scale spatial-genetic structure in British wild cherry (Prunus avium L.)

Abstract

Insights into the within-population spatial-genetic structure (SGS) of forest tree species, where little is known regarding seed and pollen dispersal patterns, enhance understanding of their ecology and provide information of value in conservation and breeding. This study utilised 13 polymorphic simple sequence repeat loci to investigate the impact of asexual recruitment, management regime and tree size on the development of SGS in wild cherry (Prunus avium L). Only 246 genotypes were identified in the 551 trees sampled, reflecting significant levels of clonal reproduction in both managed and unmanaged populations. Naturally regenerated wild cherry was spatially aggregated under both management regimes. However, in the managed population, sexually derived trees accounted for a greater proportion of the smaller size classes, whereas vegetatively produced trees dominated the smaller size classes in the unmanaged population. High overall SGS values (Sp 0.030-Sp 0.045) were observed when considering only sexually derived genets and kinship coefficients were significant up to the 120 m distance class for both populations. The inclusion of clonal ramets in the analysis significantly increased the overall SGS (Sp 0.089-Sp 0.119) as well as kinship coefficients in the 40-80 m distance classes, illustrating the dramatic impact of vegetative propagation on SGS in this species. Increased spatial aggregation and regeneration appeared to be concomitant with increased SGS in the 40 m distance class in the unmanaged population. Neighbourhood size estimates were relatively small for both populations and kinship coefficients were found to decline with distance under both management regimes, suggesting that common mechanisms may restrict gene dispersal in wild cherry.

Contemporary pollen flow, characterization of the maternal ecological neighbourhood and mating patterns in wild cherry (Prunus avium L.)

“…Less than 10% of compatible pollen donor genets grew within this distance and as such it seems that insect pollinator behaviour must be a key determinant of paternal success in wild cherry. This finding underpins the strong SGS observed earlier at this site in distance classes up to 120 m (Vaughan et al, 2007a) as a prevalence of short-distance pollination events would increase the kinship coefficient of individuals at this scale. However, mother trees differed greatly in the proportion of seed they produced that was pollinated by close neighbours and our analysis indicated that tree size and membership of a clonal genet were primary variables in determining pollination success.…”

“…Indeed, in other tree species, it has been shown that the spatial arrangement and the local density of the adult trees shape pollen dispersal patterns and a clumped arrangement has been found to favour shorter intermate distances compared with more regular distributions (Handel, 1983;Garcia et al, 2005). Significantly, cherry exhibits a clumped distribution interspersed within mixed woodland (Vaughan et al, 2007a). This is likely to cause the number and distribution of pollen donors around individual mother trees to be highly variable.…”

“…Earlier studies by our group (Vaughan et al, 2007a) showed a significant non-random genetic structure within ancient semi-natural woodland populations of wild cherry. We observed high overall spatial genetic structure (SGS) values (Sp 0.030-Sp 0.045) when considering only sexually derived genets and kinship coefficients (Fij) significant up to the 120 m distance class.…”

Molecular and quantitative signatures of biparental inbreeding depression in the self-incompatible tree species Prunus avium

“…This means that two individuals carrying the same genotype at the S-locus will not be compatible. Pollen is dispersed by bees, and seeds by gravity and birds, resulting in low dispersal distances (Granger, 2004;Schueler, 2005;Stoeckel, 2006) and consequently in significant spatial genetic structure (Vaughan et al, 2007b;. Vegetative propagation through rootsuckering commonly occurs and, as a consequence, clusters of clonal individuals can be identified within the stands (Ducci and Santi, 1997;Schueler, 2005;Schueler et al, 2006;Vaughan et al, 2007a;.…”

Microsatellites Reveal Clonal Growth and Genetically Distinct Groups in Cryptocarya chinensis in Fragmented Lower Subtropical Forest, China

“…When multiloci genotype repeats are removed, the single "genet" can be reckoned to derive from sexual reproduction (SMITH et al, 1993;VAUGHAN et al, 2007;WALSER et al, 2004), and its genetic variation can reflect the sexual reproductive status in species. Thus, by comparing with the other similar lifehistory species, the "genet-level" genetic diversity (H E = 0.582) and differentiation (F ST = 0.172) of C. chinensis are comparable to or lower than those in other studies ("data from SSR", Table 3).…”