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Inter-annual maintenance of the fine-scale genetic structure in a biennial plant

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ABSTRACT

Within plant populations, space-restricted gene movement, together with environmental heterogeneity, can result in a spatial variation in gene frequencies. In biennial plants, inter-annual flowering migrants can homogenize gene frequencies between consecutive cohorts. However, the actual impact of these migrants on spatial genetic variation remains unexplored. Here, we used 10 nuclear microsatellite and one plastid genetic marker to characterize the spatial genetic structure within two consecutive cohorts in a population of the biennial plant Erysimum mediohispanicum (Brassicaceae). We explored the maintenance of this structure between consecutive flowering cohorts at different levels of complexity, and investigated landscape effects on gene flow. We found that cohorts were not genetically differentiated and showed a spatial genetic structure defined by a negative genetic-spatial correlation at fine scale that varied in intensity with compass directions. This spatial genetic structure was maintained when comparing plants from different cohorts. Additionally, genotypes were consistently associated with environmental factors such as light availability and soil composition, but to a lesser extent compared with the spatial autocorrelation. We conclude that inter-annual migrants, in combination with limited seed dispersal and environmental heterogeneity, play a major role in shaping and maintaining the spatial genetic structure among cohorts in this biennial plant.

No MeSH data available.


Isotropic distograms.For nuclear (A) and plastid (B) markers, the average kinship at each distance class are plotted with differing symbols depending on the comparison: orange squares (2010), blue diamonds (2011) and black circles (comparisons between cohorts). Filled symbols denote significance of the value when compared with the  hypothesis of no isolation by distance. Grey filled areas represents 95% confidence intervals for the  hypothesis of no spatial structure in the between-cohort comparisons.
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f3: Isotropic distograms.For nuclear (A) and plastid (B) markers, the average kinship at each distance class are plotted with differing symbols depending on the comparison: orange squares (2010), blue diamonds (2011) and black circles (comparisons between cohorts). Filled symbols denote significance of the value when compared with the hypothesis of no isolation by distance. Grey filled areas represents 95% confidence intervals for the hypothesis of no spatial structure in the between-cohort comparisons.

Mentions: Kinship-distance distograms performed using nuclear markers showed positive significant values only at short distances (<2.5 m; Fig. 3A). The significant positive values for the first distance class (0.063 ± 0.013 in 2010; 0.071 ± 0.020 in 2011) and the negative slope of the relationship between kinship and the natural logarithm of spatial distance (−0.011 for both cohorts) lead to the same significant value of intensity of SGS (Sp = 0.012 ± 0.001; Table 2). The analysis of the plastid haplotypes showed similar results, with positive and significant values below 0.5 and 1 m in 2010 and 2011 respectively, in addition to occasional significant values at further distances (Fig. 3B). The F1 and Sp coefficients depicting SGS intensity showed significant values for both cohorts (F1 = 0.467 and 0.627; Sp = 0.207 and 0.019 in 2010 and 2011 respectively; p < 0.05).


Inter-annual maintenance of the fine-scale genetic structure in a biennial plant
Isotropic distograms.For nuclear (A) and plastid (B) markers, the average kinship at each distance class are plotted with differing symbols depending on the comparison: orange squares (2010), blue diamonds (2011) and black circles (comparisons between cohorts). Filled symbols denote significance of the value when compared with the  hypothesis of no isolation by distance. Grey filled areas represents 95% confidence intervals for the  hypothesis of no spatial structure in the between-cohort comparisons.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5121606&req=5

f3: Isotropic distograms.For nuclear (A) and plastid (B) markers, the average kinship at each distance class are plotted with differing symbols depending on the comparison: orange squares (2010), blue diamonds (2011) and black circles (comparisons between cohorts). Filled symbols denote significance of the value when compared with the hypothesis of no isolation by distance. Grey filled areas represents 95% confidence intervals for the hypothesis of no spatial structure in the between-cohort comparisons.
Mentions: Kinship-distance distograms performed using nuclear markers showed positive significant values only at short distances (<2.5 m; Fig. 3A). The significant positive values for the first distance class (0.063 ± 0.013 in 2010; 0.071 ± 0.020 in 2011) and the negative slope of the relationship between kinship and the natural logarithm of spatial distance (−0.011 for both cohorts) lead to the same significant value of intensity of SGS (Sp = 0.012 ± 0.001; Table 2). The analysis of the plastid haplotypes showed similar results, with positive and significant values below 0.5 and 1 m in 2010 and 2011 respectively, in addition to occasional significant values at further distances (Fig. 3B). The F1 and Sp coefficients depicting SGS intensity showed significant values for both cohorts (F1 = 0.467 and 0.627; Sp = 0.207 and 0.019 in 2010 and 2011 respectively; p < 0.05).

View Article: PubMed Central - PubMed

ABSTRACT

Within plant populations, space-restricted gene movement, together with environmental heterogeneity, can result in a spatial variation in gene frequencies. In biennial plants, inter-annual flowering migrants can homogenize gene frequencies between consecutive cohorts. However, the actual impact of these migrants on spatial genetic variation remains unexplored. Here, we used 10 nuclear microsatellite and one plastid genetic marker to characterize the spatial genetic structure within two consecutive cohorts in a population of the biennial plant Erysimum mediohispanicum (Brassicaceae). We explored the maintenance of this structure between consecutive flowering cohorts at different levels of complexity, and investigated landscape effects on gene flow. We found that cohorts were not genetically differentiated and showed a spatial genetic structure defined by a negative genetic-spatial correlation at fine scale that varied in intensity with compass directions. This spatial genetic structure was maintained when comparing plants from different cohorts. Additionally, genotypes were consistently associated with environmental factors such as light availability and soil composition, but to a lesser extent compared with the spatial autocorrelation. We conclude that inter-annual migrants, in combination with limited seed dispersal and environmental heterogeneity, play a major role in shaping and maintaining the spatial genetic structure among cohorts in this biennial plant.

No MeSH data available.