Local genetic population structure in an endangered plant species, Silene tatarica (Caryophyllaceae)

Abstract

Genetic substructuring in plant populations may evolve as a consequence of sampling events that occur when the population is founded or regenerated, or if gene dispersal by pollen and seeds is restricted within a population. Silene tatarica is an endangered, perennial plant species growing along periodically disturbed riverbanks in northern Finland. We investigated the mechanism behind the microspatial genetic structure of S. tatarica in four subpopulations using amplified fragment length polymorphism markers. Spatial autocorrelation revealed clear spatial genetic structure in each subpopulation, even though the pattern diminished in older subpopulations. Parentage analysis in an isolated island subpopulation indicated a very low level of selfing and avoidance of breeding between close relatives. The mean estimated pollen dispersal distance (24.10 m; SD 10.5) was significantly longer and the mean seed dispersal distance (9.07 m; SD 9.23) was considerably shorter than the mean distance between the individuals (19.20 m; SD 13.80). The estimated indirect and direct estimates of neighbourhood sizes in this subpopulation were very similar, 32.1 and 37.6, respectively. Our results suggested that the local spatial genetic structure in S. tatarica was attributed merely to the isolation-by-distance process rather than founder effect, and despite free pollen movement across population, restricted seed dispersal maintains local genetic structure in this species. Heredity advance online publication, 2 March 2005; doi:10.1038/sj.hdy.680064

Fine-scale spatial genetic structure in a predominantly selfing plant: role of seed and pollen dispersal

“…In several outcrossing herbs, mean pollen dispersal distance ranged from 5 to 15 m (Meagher and Thompson, 1987;Godt and Hamrick, 1993;Miyazaki and Isagi, 2000;Tero et al, 2005). No comparable data exist for predominantly selfing species.…”

Individual spatial aggregation correlates with between-population variation in fine-scale genetic structure of Silene ciliata (Caryophyllaceae)

“…Second, pollinator behaviour could invert the direction of the relationship between D e and FSGS. Namely, global density is assumed to cause a reduction in FSGS through decreased gene identity probabilities; however if pollinators flew longer distances (that is, increased σ e ) in low-than in high-density populations (as found in several empirical studies, see, for example, Tero et al, 2005;Barluenga et al, 2011), this effect could result in stronger genetic structure in high-density populations. This effect could explain why Sp was not significantly different in high-density PEN than in low-density LAG and NEV.…”

“…The determinants of intraspecific variation in FSGS remain comparatively underexplored, although intraspecific competition, microenvironmental selection and historic events such as founder effects or other demographic disturbances have been cited (Linhart et al, 1981;Tero et al, 2005;Chung et al, 2007). Differences in FSGS among populations may partly arise from variation in population density and spatial aggregation of individuals generated by the above-mentioned determinants.…”

Spatial distribution of genetic diversity in populations of Hagenia abyssinica (Bruce) J.F. Gmel from Ethiopia

“…The fine-scale spatial autocorrelation analysis for 21 natural populations was performed with SPAGeDi 1.2 (Hardy & Vekemans 2002) using pairwise kinship coefficients (F ij ) between individuals plotted against pairwise distances (Hardy, 2003). The inbreeding coefficient is assumed to be 0 (as for dioecious species) following Hardy et al (2006) and Tero et al (2005). The significance of the spatial genetic structure (SGS) was tested by upper and lower bounds of the 95 percent confidence interval of F ij defined after 10,000 random permutations of individuals among geographic locations.…”

“…Positive values of F ij above the 95% confidence interval were found at short distances, indicating higher genetic relatedness among neighboring individuals than among random pairs of individuals, whereas negative values of F ij occurred at larger distances, showing isolation-by-distance within a population (Tero et al 2005). Significant spatial genetic structure in H. abyssinica extends up to 80 m. This result allows us to reject the hypothesis that predicts absence of fine-scale genetic spatial patterning in H. abyssinica.…”