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Plant ontogeny, spatial distance, and soil type influence patterns of relatedness in a common Amazonian tree.

Barbosa CE, Misiewicz TM, Fine PV, Costa FR - PLoS ONE (2013)

Bottom Line: By quantifying the patterns of relatedness among plants of different sizes, we inferred the ontogenetic stage in which SGS changes occurred, and compared these effects across soil types.Contrasting relatedness patterns between seedlings and larger individuals suggests a trade-off between the negative effects of being near closely-related adults (e.g. due to herbivore and pathogen attack) and the advantage of being in a site favorable to establishment.We also found that soil texture strongly influenced density-dependence patterns, as young seedlings in clay soils were more related to each other than were seedlings in bottomland sandy soils, suggesting that the mechanisms that create and maintain patterns of SGS within a population may interact with environmental heterogeneity.

View Article: PubMed Central - PubMed

Affiliation: Graduate Program in Ecology, Instituto Nacional de Pesquisas da Amazônia (INPA), Manaus, Amazonas, Brazil. cadubarbosa@gmail.com

ABSTRACT
The formation of spatial genetic structure (SGS) may originate from different patterns of seed deposition in the landscape, and is mostly determined by seed dispersal limitation. After dispersal, mechanisms such as filtering by environmental factors or attack by herbivores/pathogens throughout plant development stages, and potentially either disrupt or intensify SGS patterns. We investigated how the genotype of Protium subserratum (Burseraceae), a common tree species in the Ducke Reserve, Brazil, is distributed across the landscape. We used seven microsatellite markers to assess the SGS among plants at different life stages and in different environments. By quantifying the patterns of relatedness among plants of different sizes, we inferred the ontogenetic stage in which SGS changes occurred, and compared these effects across soil types. Relatedness among seedlings decreased when distance between seedlings increased, especially for the youngest seedlings. However, this trend was not continued by older plants, as relatedness values were higher among neighboring individuals of the juvenile and adult size class. Contrasting relatedness patterns between seedlings and larger individuals suggests a trade-off between the negative effects of being near closely-related adults (e.g. due to herbivore and pathogen attack) and the advantage of being in a site favorable to establishment. We also found that soil texture strongly influenced density-dependence patterns, as young seedlings in clay soils were more related to each other than were seedlings in bottomland sandy soils, suggesting that the mechanisms that create and maintain patterns of SGS within a population may interact with environmental heterogeneity.

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Spatial genetic structure of Protium subserratum seedlings at different soil types.Correlograms of SGS for 40 cm height P. subserratum seedlings at plots with different soil texture at Ducke: (A) are seedlings in clayey soils and (B) are seedlings in sandy soils. The points indicate r-values with error bars and the dashed lines represent 95% CI limits around the mean value (r = 0) of the  distribution of a random distribution of alleles in space. The number of comparisons for each distance class is reported in table 5.
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pone-0062639-g005: Spatial genetic structure of Protium subserratum seedlings at different soil types.Correlograms of SGS for 40 cm height P. subserratum seedlings at plots with different soil texture at Ducke: (A) are seedlings in clayey soils and (B) are seedlings in sandy soils. The points indicate r-values with error bars and the dashed lines represent 95% CI limits around the mean value (r = 0) of the distribution of a random distribution of alleles in space. The number of comparisons for each distance class is reported in table 5.

Mentions: The pattern of SGS among first-year and young seedlings was significantly different from random when all samples from all plots were pooled, regardless of their position along the environmental gradient. Since soil texture is a good proxy for topographic position and correlates with plant species composition at our study site [28], [29], we ran two separate SGS analyses based on plot soil texture. The results have shown that soil type influences SGS patterns, as we found positive autocorrelation in the clay plots throughout all distance intervals (Table 5). By contrast, seedlings from sandy soils were significantly positively autocorrelated only in the first three distance classes (up to 150 m – Table 5) after which individuals were no more related with each other than would be expected by chance, since r-values fall within the CI area (Fig. 5).


Plant ontogeny, spatial distance, and soil type influence patterns of relatedness in a common Amazonian tree.

Barbosa CE, Misiewicz TM, Fine PV, Costa FR - PLoS ONE (2013)

Spatial genetic structure of Protium subserratum seedlings at different soil types.Correlograms of SGS for 40 cm height P. subserratum seedlings at plots with different soil texture at Ducke: (A) are seedlings in clayey soils and (B) are seedlings in sandy soils. The points indicate r-values with error bars and the dashed lines represent 95% CI limits around the mean value (r = 0) of the  distribution of a random distribution of alleles in space. The number of comparisons for each distance class is reported in table 5.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3646837&req=5

pone-0062639-g005: Spatial genetic structure of Protium subserratum seedlings at different soil types.Correlograms of SGS for 40 cm height P. subserratum seedlings at plots with different soil texture at Ducke: (A) are seedlings in clayey soils and (B) are seedlings in sandy soils. The points indicate r-values with error bars and the dashed lines represent 95% CI limits around the mean value (r = 0) of the distribution of a random distribution of alleles in space. The number of comparisons for each distance class is reported in table 5.
Mentions: The pattern of SGS among first-year and young seedlings was significantly different from random when all samples from all plots were pooled, regardless of their position along the environmental gradient. Since soil texture is a good proxy for topographic position and correlates with plant species composition at our study site [28], [29], we ran two separate SGS analyses based on plot soil texture. The results have shown that soil type influences SGS patterns, as we found positive autocorrelation in the clay plots throughout all distance intervals (Table 5). By contrast, seedlings from sandy soils were significantly positively autocorrelated only in the first three distance classes (up to 150 m – Table 5) after which individuals were no more related with each other than would be expected by chance, since r-values fall within the CI area (Fig. 5).

Bottom Line: By quantifying the patterns of relatedness among plants of different sizes, we inferred the ontogenetic stage in which SGS changes occurred, and compared these effects across soil types.Contrasting relatedness patterns between seedlings and larger individuals suggests a trade-off between the negative effects of being near closely-related adults (e.g. due to herbivore and pathogen attack) and the advantage of being in a site favorable to establishment.We also found that soil texture strongly influenced density-dependence patterns, as young seedlings in clay soils were more related to each other than were seedlings in bottomland sandy soils, suggesting that the mechanisms that create and maintain patterns of SGS within a population may interact with environmental heterogeneity.

View Article: PubMed Central - PubMed

Affiliation: Graduate Program in Ecology, Instituto Nacional de Pesquisas da Amazônia (INPA), Manaus, Amazonas, Brazil. cadubarbosa@gmail.com

ABSTRACT
The formation of spatial genetic structure (SGS) may originate from different patterns of seed deposition in the landscape, and is mostly determined by seed dispersal limitation. After dispersal, mechanisms such as filtering by environmental factors or attack by herbivores/pathogens throughout plant development stages, and potentially either disrupt or intensify SGS patterns. We investigated how the genotype of Protium subserratum (Burseraceae), a common tree species in the Ducke Reserve, Brazil, is distributed across the landscape. We used seven microsatellite markers to assess the SGS among plants at different life stages and in different environments. By quantifying the patterns of relatedness among plants of different sizes, we inferred the ontogenetic stage in which SGS changes occurred, and compared these effects across soil types. Relatedness among seedlings decreased when distance between seedlings increased, especially for the youngest seedlings. However, this trend was not continued by older plants, as relatedness values were higher among neighboring individuals of the juvenile and adult size class. Contrasting relatedness patterns between seedlings and larger individuals suggests a trade-off between the negative effects of being near closely-related adults (e.g. due to herbivore and pathogen attack) and the advantage of being in a site favorable to establishment. We also found that soil texture strongly influenced density-dependence patterns, as young seedlings in clay soils were more related to each other than were seedlings in bottomland sandy soils, suggesting that the mechanisms that create and maintain patterns of SGS within a population may interact with environmental heterogeneity.

Show MeSH