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Temporal stability of genetic variability and differentiation in the three-spined stickleback (Gasterosteus aculeatus).

DeFaveri J, Merilä J - PLoS ONE (2015)

Bottom Line: In spite of the continued surge of interest in the genetics of three-spined stickleback (Gasterosteus aculeatus) populations, little attention has been paid towards the temporal stability of allele frequency distributions, and whether there are consistent differences in effective size (Ne) of local populations.In spite of the marked differences in genetic variability and differentiation among the study sites, the temporal differences in allele frequencies, as well as measures of genetic diversity and differentiation, were negligible.Hence, we conclude that allele frequencies in putatively neutral markers in three-spined sticklebacks seem to be temporally stable - at least over periods of few generations - across a wide range of habitat types differing markedly in levels of genetic variability, effective population size and gene flow.

View Article: PubMed Central - PubMed

Affiliation: Ecological Genetics Research Unit, Department of Biosciences, University of Helsinki, Helsinki, Finland.

ABSTRACT
Temporal variation in allele frequencies, whether caused by deterministic or stochastic forces, can inform us about interesting demographic and evolutionary phenomena occurring in wild populations. In spite of the continued surge of interest in the genetics of three-spined stickleback (Gasterosteus aculeatus) populations, little attention has been paid towards the temporal stability of allele frequency distributions, and whether there are consistent differences in effective size (Ne) of local populations. We investigated temporal stability of genetic variability and differentiation in 15 microsatellite loci within and among eight collection sites of varying habitat type, surveyed twice over a six-year time period. In addition, Nes were estimated with the expectation that they would be lowest in isolated ponds, intermediate in larger lakes and largest in open marine sites. In spite of the marked differences in genetic variability and differentiation among the study sites, the temporal differences in allele frequencies, as well as measures of genetic diversity and differentiation, were negligible. Accordingly, the Ne estimates were temporally stable, but tended to be lower in ponds than in lake or marine habitats. Hence, we conclude that allele frequencies in putatively neutral markers in three-spined sticklebacks seem to be temporally stable - at least over periods of few generations - across a wide range of habitat types differing markedly in levels of genetic variability, effective population size and gene flow.

No MeSH data available.


Correlation between (a) expected heterozygosity and (b) pairwise FST values from two different sampling occasions.Closed circles denote pairwise FST among sea populations; triangles among lake populations; squares among pond populations; open circles between habitat comparisons.
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pone.0123891.g002: Correlation between (a) expected heterozygosity and (b) pairwise FST values from two different sampling occasions.Closed circles denote pairwise FST among sea populations; triangles among lake populations; squares among pond populations; open circles between habitat comparisons.

Mentions: There was significant genetic heterogeneity among populations in all genetic diversity measures: marine populations were genetically more variable than the lake populations, which were more variable than the pond populations (Table 1). However, there were no temporal differences in the allele frequencies in any loci in any of the populations between the two sampling occasions (Fisher’s exact probability tests, P > 0.05). Accordingly, different estimates of genetic variability were similar (Kruskal-Wallis test, P > 0.05 for HE, A, and AR) and strongly correlated (rs = 0.77–0.93; n = 8, P ≤ 0.001) between the two sampling occasions (e.g. Fig 2a). FIS values were small and similar in all populations and across the two sampling periods (Table 1).


Temporal stability of genetic variability and differentiation in the three-spined stickleback (Gasterosteus aculeatus).

DeFaveri J, Merilä J - PLoS ONE (2015)

Correlation between (a) expected heterozygosity and (b) pairwise FST values from two different sampling occasions.Closed circles denote pairwise FST among sea populations; triangles among lake populations; squares among pond populations; open circles between habitat comparisons.
© Copyright Policy
Related In: Results  -  Collection

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pone.0123891.g002: Correlation between (a) expected heterozygosity and (b) pairwise FST values from two different sampling occasions.Closed circles denote pairwise FST among sea populations; triangles among lake populations; squares among pond populations; open circles between habitat comparisons.
Mentions: There was significant genetic heterogeneity among populations in all genetic diversity measures: marine populations were genetically more variable than the lake populations, which were more variable than the pond populations (Table 1). However, there were no temporal differences in the allele frequencies in any loci in any of the populations between the two sampling occasions (Fisher’s exact probability tests, P > 0.05). Accordingly, different estimates of genetic variability were similar (Kruskal-Wallis test, P > 0.05 for HE, A, and AR) and strongly correlated (rs = 0.77–0.93; n = 8, P ≤ 0.001) between the two sampling occasions (e.g. Fig 2a). FIS values were small and similar in all populations and across the two sampling periods (Table 1).

Bottom Line: In spite of the continued surge of interest in the genetics of three-spined stickleback (Gasterosteus aculeatus) populations, little attention has been paid towards the temporal stability of allele frequency distributions, and whether there are consistent differences in effective size (Ne) of local populations.In spite of the marked differences in genetic variability and differentiation among the study sites, the temporal differences in allele frequencies, as well as measures of genetic diversity and differentiation, were negligible.Hence, we conclude that allele frequencies in putatively neutral markers in three-spined sticklebacks seem to be temporally stable - at least over periods of few generations - across a wide range of habitat types differing markedly in levels of genetic variability, effective population size and gene flow.

View Article: PubMed Central - PubMed

Affiliation: Ecological Genetics Research Unit, Department of Biosciences, University of Helsinki, Helsinki, Finland.

ABSTRACT
Temporal variation in allele frequencies, whether caused by deterministic or stochastic forces, can inform us about interesting demographic and evolutionary phenomena occurring in wild populations. In spite of the continued surge of interest in the genetics of three-spined stickleback (Gasterosteus aculeatus) populations, little attention has been paid towards the temporal stability of allele frequency distributions, and whether there are consistent differences in effective size (Ne) of local populations. We investigated temporal stability of genetic variability and differentiation in 15 microsatellite loci within and among eight collection sites of varying habitat type, surveyed twice over a six-year time period. In addition, Nes were estimated with the expectation that they would be lowest in isolated ponds, intermediate in larger lakes and largest in open marine sites. In spite of the marked differences in genetic variability and differentiation among the study sites, the temporal differences in allele frequencies, as well as measures of genetic diversity and differentiation, were negligible. Accordingly, the Ne estimates were temporally stable, but tended to be lower in ponds than in lake or marine habitats. Hence, we conclude that allele frequencies in putatively neutral markers in three-spined sticklebacks seem to be temporally stable - at least over periods of few generations - across a wide range of habitat types differing markedly in levels of genetic variability, effective population size and gene flow.

No MeSH data available.