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Rapid Buildup of Genetic Diversity in Founder Populations of the Gynodioecious Plant Species Origanum vulgare after Semi-Natural Grassland Restoration.

Helsen K, Jacquemyn H, Hermy M, Vandepitte K, Honnay O - PLoS ONE (2013)

Bottom Line: We compared the genetic diversity and differentiation of fourteen recent populations with that of thirteen old, putative source populations, and we evaluated the effects of spatial configuration of the populations on colonization patterns.We did not observe decreased genetic diversity in recent populations, or inflated genetic differentiation among them.Nevertheless, a significantly higher inbreeding coefficient was observed in recent populations, although this was not associated with negative fitness effects.

View Article: PubMed Central - PubMed

Affiliation: Plant Conservation and Population Biology, Department of Biology, University of Leuven, Leuven, Belgium.

ABSTRACT
In most landscapes the success of habitat restoration is largely dependent on spontaneous colonization of plant species. This colonization process, and the outcome of restoration practices, can only be considered successful if the genetic makeup of founding populations is not eroded through founder effects and subsequent genetic drift. Here we used 10 microsatellite markers to investigate the genetic effects of recent colonization of the long-lived gynodioecious species Origanum vulgare in restored semi-natural grassland patches. We compared the genetic diversity and differentiation of fourteen recent populations with that of thirteen old, putative source populations, and we evaluated the effects of spatial configuration of the populations on colonization patterns. We did not observe decreased genetic diversity in recent populations, or inflated genetic differentiation among them. Nevertheless, a significantly higher inbreeding coefficient was observed in recent populations, although this was not associated with negative fitness effects. Overall population genetic differentiation was low (FST = 0.040). Individuals of restored populations were assigned to on average 6.1 different source populations (likely following the 'migrant pool' model). Gene flow was, however, affected by the spatial configuration of the grasslands, with gene flow into the recent populations mainly originating from nearby source populations. This study demonstrates how spontaneous colonization after habitat restoration can lead to viable populations in a relatively short time, overcoming pronounced founder effects, when several source populations are nearby. Restored populations can therefore rapidly act as stepping stones and sources of genetic diversity, likely increasing overall metapopulation viability of the study species.

No MeSH data available.


Related in: MedlinePlus

Difference in observed heterozygosity and inbreeding coefficient between recent and old populations.A. Boxplot for observed heterozygosity (HO). B. Boxplot for inbreeding coefficient (FIS).
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pone-0067255-g003: Difference in observed heterozygosity and inbreeding coefficient between recent and old populations.A. Boxplot for observed heterozygosity (HO). B. Boxplot for inbreeding coefficient (FIS).

Mentions: Recent populations had a median of 708 plants (range: 150–5000), with median of 9.7% female plants (range: 3.3–25.9%). The number of alleles per population (A) varied between 3.1 and 4.1 alleles per population (average: 3.6), whereas observed heterozygosity varied between 0.37 and 0.48 (average: 0.42) for recent populations (Table 1). Old populations had a median of 9.1% female plants (range: 4.6–53.2%) with a median population size of 459 plants (range: 99–2250), a mean A of 3.7 (range: 3.3–4.2) and a mean HO of 0.44 (range: 0.41–0.54) (Table 1). No significant difference between recent and old populations was found for population size (t = 1.0, P = 0.31), the percentage of female flowers (t = –2.2, P = 0.56) or the variance in the percentage of female flowers (F = 1.2, P = 0.76). The percentage of female flowers was not related to population size. The mean number of alleles increased with increasing percentage of female plants. However, this pattern was influenced by population size, with a decrease in the positive correlation with decreasing population size (significant interaction term, Table 2). This was visualized by dividing population size in small (<500 plants) and large populations (>1000 plants), and performing a Pearson correlation test independently for small and large populations (Fig. 2). Both HO and FIS were affected by population age, with a significantly lower observed heterozygosity and higher inbreeding in recent populations (Table 2, Fig. 3). Expected heterozygosity (HE) was not affected by any of the measured population characteristics. Linkage disequilibrium (LD) on the other hand, decreased with increasing population size, but was unaffected by population age (Table 2). When we tested for a correlation between LD and population size for recent and old populations independently, we found a significant correlation for old populations (r = –0.61, P = 0.027), but not for recent populations (r = –0.43, P = 0.12). We found no evidence of recent genetic bottlenecks in any of the 27 populations. Reproductive success was not affected by FIS (germination rate: r = 0.025, P = 0.90; seed weight: r = –0.084, P = 0.68) or population age (germination rate: t = –1.068, P = 0.30; seed weight: t = 0.26, P = 0.80).


Rapid Buildup of Genetic Diversity in Founder Populations of the Gynodioecious Plant Species Origanum vulgare after Semi-Natural Grassland Restoration.

Helsen K, Jacquemyn H, Hermy M, Vandepitte K, Honnay O - PLoS ONE (2013)

Difference in observed heterozygosity and inbreeding coefficient between recent and old populations.A. Boxplot for observed heterozygosity (HO). B. Boxplot for inbreeding coefficient (FIS).
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3686717&req=5

pone-0067255-g003: Difference in observed heterozygosity and inbreeding coefficient between recent and old populations.A. Boxplot for observed heterozygosity (HO). B. Boxplot for inbreeding coefficient (FIS).
Mentions: Recent populations had a median of 708 plants (range: 150–5000), with median of 9.7% female plants (range: 3.3–25.9%). The number of alleles per population (A) varied between 3.1 and 4.1 alleles per population (average: 3.6), whereas observed heterozygosity varied between 0.37 and 0.48 (average: 0.42) for recent populations (Table 1). Old populations had a median of 9.1% female plants (range: 4.6–53.2%) with a median population size of 459 plants (range: 99–2250), a mean A of 3.7 (range: 3.3–4.2) and a mean HO of 0.44 (range: 0.41–0.54) (Table 1). No significant difference between recent and old populations was found for population size (t = 1.0, P = 0.31), the percentage of female flowers (t = –2.2, P = 0.56) or the variance in the percentage of female flowers (F = 1.2, P = 0.76). The percentage of female flowers was not related to population size. The mean number of alleles increased with increasing percentage of female plants. However, this pattern was influenced by population size, with a decrease in the positive correlation with decreasing population size (significant interaction term, Table 2). This was visualized by dividing population size in small (<500 plants) and large populations (>1000 plants), and performing a Pearson correlation test independently for small and large populations (Fig. 2). Both HO and FIS were affected by population age, with a significantly lower observed heterozygosity and higher inbreeding in recent populations (Table 2, Fig. 3). Expected heterozygosity (HE) was not affected by any of the measured population characteristics. Linkage disequilibrium (LD) on the other hand, decreased with increasing population size, but was unaffected by population age (Table 2). When we tested for a correlation between LD and population size for recent and old populations independently, we found a significant correlation for old populations (r = –0.61, P = 0.027), but not for recent populations (r = –0.43, P = 0.12). We found no evidence of recent genetic bottlenecks in any of the 27 populations. Reproductive success was not affected by FIS (germination rate: r = 0.025, P = 0.90; seed weight: r = –0.084, P = 0.68) or population age (germination rate: t = –1.068, P = 0.30; seed weight: t = 0.26, P = 0.80).

Bottom Line: We compared the genetic diversity and differentiation of fourteen recent populations with that of thirteen old, putative source populations, and we evaluated the effects of spatial configuration of the populations on colonization patterns.We did not observe decreased genetic diversity in recent populations, or inflated genetic differentiation among them.Nevertheless, a significantly higher inbreeding coefficient was observed in recent populations, although this was not associated with negative fitness effects.

View Article: PubMed Central - PubMed

Affiliation: Plant Conservation and Population Biology, Department of Biology, University of Leuven, Leuven, Belgium.

ABSTRACT
In most landscapes the success of habitat restoration is largely dependent on spontaneous colonization of plant species. This colonization process, and the outcome of restoration practices, can only be considered successful if the genetic makeup of founding populations is not eroded through founder effects and subsequent genetic drift. Here we used 10 microsatellite markers to investigate the genetic effects of recent colonization of the long-lived gynodioecious species Origanum vulgare in restored semi-natural grassland patches. We compared the genetic diversity and differentiation of fourteen recent populations with that of thirteen old, putative source populations, and we evaluated the effects of spatial configuration of the populations on colonization patterns. We did not observe decreased genetic diversity in recent populations, or inflated genetic differentiation among them. Nevertheless, a significantly higher inbreeding coefficient was observed in recent populations, although this was not associated with negative fitness effects. Overall population genetic differentiation was low (FST = 0.040). Individuals of restored populations were assigned to on average 6.1 different source populations (likely following the 'migrant pool' model). Gene flow was, however, affected by the spatial configuration of the grasslands, with gene flow into the recent populations mainly originating from nearby source populations. This study demonstrates how spontaneous colonization after habitat restoration can lead to viable populations in a relatively short time, overcoming pronounced founder effects, when several source populations are nearby. Restored populations can therefore rapidly act as stepping stones and sources of genetic diversity, likely increasing overall metapopulation viability of the study species.

No MeSH data available.


Related in: MedlinePlus