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Modelling single nucleotide effects in phosphoglucose isomerase on dispersal in the Glanville fritillary butterfly: coupling of ecological and evolutionary dynamics.

Zheng C, Ovaskainen O, Hanski I - Philos. Trans. R. Soc. Lond., B, Biol. Sci. (2009)

Bottom Line: Based on empirical results for a single nucleotide polymorphism (SNP) in the phosphoglucose isomerase (Pgi) gene, we assume that dispersal rate in the landscape matrix, fecundity and survival are affected by a locus with two alleles, A and C, individuals with the C allele being more mobile.The model was successfully tested with two independent empirical datasets on spatial variation in Pgi allele frequency.Our results indicate that the strength of the coupling of the ecological and evolutionary dynamics depends on the spatial scale and is asymmetric, demographic dynamics having a greater immediate impact on genetic dynamics than vice versa.

View Article: PubMed Central - PubMed

Affiliation: Department of Biological and Environmental Sciences, University of Helsinki, Helsinki, Finland.

ABSTRACT
Dispersal comprises a complex life-history syndrome that influences the demographic dynamics of especially those species that live in fragmented landscapes, the structure of which may in turn be expected to impose selection on dispersal. We have constructed an individual-based evolutionary sexual model of dispersal for species occurring as metapopulations in habitat patch networks. The model assumes correlated random walk dispersal with edge-mediated behaviour (habitat selection) and spatially correlated stochastic local dynamics. The model is parametrized with extensive data for the Glanville fritillary butterfly. Based on empirical results for a single nucleotide polymorphism (SNP) in the phosphoglucose isomerase (Pgi) gene, we assume that dispersal rate in the landscape matrix, fecundity and survival are affected by a locus with two alleles, A and C, individuals with the C allele being more mobile. The model was successfully tested with two independent empirical datasets on spatial variation in Pgi allele frequency. First, at the level of local populations, the frequency of the C allele is the highest in newly established isolated populations and the lowest in old isolated populations. Second, at the level of sub-networks with dissimilar numbers and connectivities of patches, the frequency of C increases with decreasing network size and hence with decreasing average metapopulation size. The frequency of C is the highest in landscapes where local extinction risk is high and where there are abundant opportunities to establish new populations. Our results indicate that the strength of the coupling of the ecological and evolutionary dynamics depends on the spatial scale and is asymmetric, demographic dynamics having a greater immediate impact on genetic dynamics than vice versa.

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Comparison between predicted and observed spatial variations in the frequency of the C allele among local populations. (a,c) The frequency of C as a function of connectivity in newly established (open circles, dashed regression lines) and old populations (filled circles, solid regression lines) is given. (b,d) One snapshot of the frequency of C in sub-networks of habitat patches as a function of the pooled number of larval groups in the network at the time of sampling is shown. In the regression lines, the networks in which the C allele was absent (frequency 0) have been excluded. (a,b) Model predictions, (c) the empirical result from fig. 2b in Haag et al. (2005) and (d) an empirical result calculated with the data described by Hanski & Saccheri (2006) are shown. (e) How the slope in (a) depends on the age of the population (years since the population has been established), with data for 1500 independent snapshots is shown.
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fig4: Comparison between predicted and observed spatial variations in the frequency of the C allele among local populations. (a,c) The frequency of C as a function of connectivity in newly established (open circles, dashed regression lines) and old populations (filled circles, solid regression lines) is given. (b,d) One snapshot of the frequency of C in sub-networks of habitat patches as a function of the pooled number of larval groups in the network at the time of sampling is shown. In the regression lines, the networks in which the C allele was absent (frequency 0) have been excluded. (a,b) Model predictions, (c) the empirical result from fig. 2b in Haag et al. (2005) and (d) an empirical result calculated with the data described by Hanski & Saccheri (2006) are shown. (e) How the slope in (a) depends on the age of the population (years since the population has been established), with data for 1500 independent snapshots is shown.

Mentions: First, we compare the frequency of C in newly established versus old local populations. Consistent with previous empirical work (§2), the newly established populations were colonized in the previous generation, while, by definition, the old populations had persisted more than 5 years since the colonization. Figure 4a gives the predicted result for one snapshot from the stationary state of the model. In this snapshot, the frequency of C decreases with increasing connectivity in newly established populations, but increases with connectivity in old populations. Examining the slope of the frequency of C against connectivity in 150 independent snapshots shows that the slope in the simulations was higher for old than that for the newly established populations with probability 0.96. The mean slope increases systematically with population age and turns from negative to positive at the age of approximately 5 years (figure 4e). Variation in the estimate of the mean slope increases with population age as the number of persisting local populations decreases rapidly with increasing age.


Modelling single nucleotide effects in phosphoglucose isomerase on dispersal in the Glanville fritillary butterfly: coupling of ecological and evolutionary dynamics.

Zheng C, Ovaskainen O, Hanski I - Philos. Trans. R. Soc. Lond., B, Biol. Sci. (2009)

Comparison between predicted and observed spatial variations in the frequency of the C allele among local populations. (a,c) The frequency of C as a function of connectivity in newly established (open circles, dashed regression lines) and old populations (filled circles, solid regression lines) is given. (b,d) One snapshot of the frequency of C in sub-networks of habitat patches as a function of the pooled number of larval groups in the network at the time of sampling is shown. In the regression lines, the networks in which the C allele was absent (frequency 0) have been excluded. (a,b) Model predictions, (c) the empirical result from fig. 2b in Haag et al. (2005) and (d) an empirical result calculated with the data described by Hanski & Saccheri (2006) are shown. (e) How the slope in (a) depends on the age of the population (years since the population has been established), with data for 1500 independent snapshots is shown.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2690501&req=5

fig4: Comparison between predicted and observed spatial variations in the frequency of the C allele among local populations. (a,c) The frequency of C as a function of connectivity in newly established (open circles, dashed regression lines) and old populations (filled circles, solid regression lines) is given. (b,d) One snapshot of the frequency of C in sub-networks of habitat patches as a function of the pooled number of larval groups in the network at the time of sampling is shown. In the regression lines, the networks in which the C allele was absent (frequency 0) have been excluded. (a,b) Model predictions, (c) the empirical result from fig. 2b in Haag et al. (2005) and (d) an empirical result calculated with the data described by Hanski & Saccheri (2006) are shown. (e) How the slope in (a) depends on the age of the population (years since the population has been established), with data for 1500 independent snapshots is shown.
Mentions: First, we compare the frequency of C in newly established versus old local populations. Consistent with previous empirical work (§2), the newly established populations were colonized in the previous generation, while, by definition, the old populations had persisted more than 5 years since the colonization. Figure 4a gives the predicted result for one snapshot from the stationary state of the model. In this snapshot, the frequency of C decreases with increasing connectivity in newly established populations, but increases with connectivity in old populations. Examining the slope of the frequency of C against connectivity in 150 independent snapshots shows that the slope in the simulations was higher for old than that for the newly established populations with probability 0.96. The mean slope increases systematically with population age and turns from negative to positive at the age of approximately 5 years (figure 4e). Variation in the estimate of the mean slope increases with population age as the number of persisting local populations decreases rapidly with increasing age.

Bottom Line: Based on empirical results for a single nucleotide polymorphism (SNP) in the phosphoglucose isomerase (Pgi) gene, we assume that dispersal rate in the landscape matrix, fecundity and survival are affected by a locus with two alleles, A and C, individuals with the C allele being more mobile.The model was successfully tested with two independent empirical datasets on spatial variation in Pgi allele frequency.Our results indicate that the strength of the coupling of the ecological and evolutionary dynamics depends on the spatial scale and is asymmetric, demographic dynamics having a greater immediate impact on genetic dynamics than vice versa.

View Article: PubMed Central - PubMed

Affiliation: Department of Biological and Environmental Sciences, University of Helsinki, Helsinki, Finland.

ABSTRACT
Dispersal comprises a complex life-history syndrome that influences the demographic dynamics of especially those species that live in fragmented landscapes, the structure of which may in turn be expected to impose selection on dispersal. We have constructed an individual-based evolutionary sexual model of dispersal for species occurring as metapopulations in habitat patch networks. The model assumes correlated random walk dispersal with edge-mediated behaviour (habitat selection) and spatially correlated stochastic local dynamics. The model is parametrized with extensive data for the Glanville fritillary butterfly. Based on empirical results for a single nucleotide polymorphism (SNP) in the phosphoglucose isomerase (Pgi) gene, we assume that dispersal rate in the landscape matrix, fecundity and survival are affected by a locus with two alleles, A and C, individuals with the C allele being more mobile. The model was successfully tested with two independent empirical datasets on spatial variation in Pgi allele frequency. First, at the level of local populations, the frequency of the C allele is the highest in newly established isolated populations and the lowest in old isolated populations. Second, at the level of sub-networks with dissimilar numbers and connectivities of patches, the frequency of C increases with decreasing network size and hence with decreasing average metapopulation size. The frequency of C is the highest in landscapes where local extinction risk is high and where there are abundant opportunities to establish new populations. Our results indicate that the strength of the coupling of the ecological and evolutionary dynamics depends on the spatial scale and is asymmetric, demographic dynamics having a greater immediate impact on genetic dynamics than vice versa.

Show MeSH
Related in: MedlinePlus