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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.


Neighbor-joining tree based on DCE distances [52], rooted with a population from the North Sea.Bootstrap values above 50% are indicated at nodes. Genetic clusters as detected with STRUCTURE [53] are indicated at branch tips.
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pone.0123891.g003: Neighbor-joining tree based on DCE distances [52], rooted with a population from the North Sea.Bootstrap values above 50% are indicated at nodes. Genetic clusters as detected with STRUCTURE [53] are indicated at branch tips.

Mentions: The overall FST across all populations was 0.199 (95% CI: 0.156–0.238, P < 0.05) in 2003 and 0.209 (95% CI: 0.107–0.246, P < 0.05) in 2009, and the pairwise estimates across populations over time were strongly positively correlated (r = 0.99; n = 8, P < 0.001; Fig 2b). Within each habitat type, overall FST was similar between years (Table 2). Accordingly, the temporal replicates branched together in the neighbor-joining tree, with high bootstrap support for the freshwater populations (Fig 3). STRUCTURE also assigned temporal replicates to the same genetic cluster for each population (Fig 3). Each of the freshwater sampling locations were assigned as independent clusters (K = 4), and the most likely K for the sea populations was three (Fig 3). Among all populations, 20.36% of the genetic variation was attributed to differences among habitats, but the variance component due to temporal changes within localities was negative and non-significant (Table 3). This was true whether all populations were analyzed together or when each habitat was analyzed separately (Table 3).


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

DeFaveri J, Merilä J - PLoS ONE (2015)

Neighbor-joining tree based on DCE distances [52], rooted with a population from the North Sea.Bootstrap values above 50% are indicated at nodes. Genetic clusters as detected with STRUCTURE [53] are indicated at branch tips.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4390281&req=5

pone.0123891.g003: Neighbor-joining tree based on DCE distances [52], rooted with a population from the North Sea.Bootstrap values above 50% are indicated at nodes. Genetic clusters as detected with STRUCTURE [53] are indicated at branch tips.
Mentions: The overall FST across all populations was 0.199 (95% CI: 0.156–0.238, P < 0.05) in 2003 and 0.209 (95% CI: 0.107–0.246, P < 0.05) in 2009, and the pairwise estimates across populations over time were strongly positively correlated (r = 0.99; n = 8, P < 0.001; Fig 2b). Within each habitat type, overall FST was similar between years (Table 2). Accordingly, the temporal replicates branched together in the neighbor-joining tree, with high bootstrap support for the freshwater populations (Fig 3). STRUCTURE also assigned temporal replicates to the same genetic cluster for each population (Fig 3). Each of the freshwater sampling locations were assigned as independent clusters (K = 4), and the most likely K for the sea populations was three (Fig 3). Among all populations, 20.36% of the genetic variation was attributed to differences among habitats, but the variance component due to temporal changes within localities was negative and non-significant (Table 3). This was true whether all populations were analyzed together or when each habitat was analyzed separately (Table 3).

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.