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Climate change drives microevolution in a wild bird.

Karell P, Ahola K, Karstinen T, Valkama J, Brommer JE - Nat Commun (2011)

Bottom Line: As winter conditions became milder in the last decades, selection against the brown morph diminished.Concurrent with this reduced selection, the frequency of brown morphs increased rapidly in our study population during the last 28 years and nationwide during the last 48 years.Hence, we show the first evidence that recent climate change alters natural selection in a wild population leading to a microevolutionary response, which demonstrates the ability of wild populations to evolve in response to climate change.

View Article: PubMed Central - PubMed

Affiliation: Bird Ecology Unit, Department of Biosciences, University of Helsinki, PO Box 65 (Viikinkaari 1), Helsinki FI-00014, Finland. patrik.karell@helsinki.fi

ABSTRACT
To ensure long-term persistence, organisms must adapt to climate change, but an evolutionary response to a quantified selection pressure driven by climate change has not been empirically demonstrated in a wild population. Here, we show that pheomelanin-based plumage colouration in tawny owls is a highly heritable trait, consistent with a simple Mendelian pattern of brown (dark) dominance over grey (pale). We show that strong viability selection against the brown morph occurs, but only under snow-rich winters. As winter conditions became milder in the last decades, selection against the brown morph diminished. Concurrent with this reduced selection, the frequency of brown morphs increased rapidly in our study population during the last 28 years and nationwide during the last 48 years. Hence, we show the first evidence that recent climate change alters natural selection in a wild population leading to a microevolutionary response, which demonstrates the ability of wild populations to evolve in response to climate change.

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Related in: MedlinePlus

Genetic models of inheritance of colouration.Number of brown (red bar) and grey (grey bar) offspring colour morphs produced by different combinations of parental colour morphs (B×B, B×G and G×G). The first columns show the observations in the field, second, third and fourth columns show the expected number of offspring colour morphs according to models with brown dominance, grey dominance and an additive genetic model, respectively. The lines above the bars show a G-test of association between models and their significance (NS: P=0.58, **P<0.002, ***P<0.0001).
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f2: Genetic models of inheritance of colouration.Number of brown (red bar) and grey (grey bar) offspring colour morphs produced by different combinations of parental colour morphs (B×B, B×G and G×G). The first columns show the observations in the field, second, third and fourth columns show the expected number of offspring colour morphs according to models with brown dominance, grey dominance and an additive genetic model, respectively. The lines above the bars show a G-test of association between models and their significance (NS: P=0.58, **P<0.002, ***P<0.0001).

Mentions: The model assuming brown dominance (Supplementary Table S1) produces a ratio of brown/grey phenotypes that almost exactly matches what is expected under this inheritance model in Hardy–Weinberg equilibrium (52.8% of offsprings are observed and 55.2% are expected to be brown, G1=0.308, P=0.58; Fig. 2, Supplementary Table S2). Repeating the above, but assuming that the allele for grey morph is dominant over the allele for brown produces a poorer fit between observed and expected ratio of the offspring (G2=12.98, P=0.0015; Fig. 2). There are more brown offspring observed than expected when assuming full dominance of the grey allele over brown. The purely additive model also fitted the data poorly. In this particular case, the colour scores of the adults were such that the additive model predicted that all offspring from monomorphic crosses were the same morph as the parents; thus, these crosses are not informative for testing. However, focusing on the heteromorphic (BxG) cross, it is clear that there are more offspring of the brown morph observed than expected also under the assumption of an additive genetic inheritance (G1=70.9, P<0.0001; Fig. 2). Alternative approaches for statistically comparing the observed and expected frequencies of morphs all provided the same conclusion (Supplementary Information). We thus conclude from the above exercises on the basis of comparing fledglings' morphs with their parents' morphs that we find evidence for genetic dominance of brown over grey, whereas dominance of grey and purely additive genetic effects are not supported by this data. Although this modelling is not exhaustive, it does show that the tawny owl phenotypic morph has a genetic architecture that relies on few genes with large effects, which is consistent with a Mendelian inheritance of colouration based on one locus with a 'brown' allele dominant over a 'grey' allele.


Climate change drives microevolution in a wild bird.

Karell P, Ahola K, Karstinen T, Valkama J, Brommer JE - Nat Commun (2011)

Genetic models of inheritance of colouration.Number of brown (red bar) and grey (grey bar) offspring colour morphs produced by different combinations of parental colour morphs (B×B, B×G and G×G). The first columns show the observations in the field, second, third and fourth columns show the expected number of offspring colour morphs according to models with brown dominance, grey dominance and an additive genetic model, respectively. The lines above the bars show a G-test of association between models and their significance (NS: P=0.58, **P<0.002, ***P<0.0001).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3105316&req=5

f2: Genetic models of inheritance of colouration.Number of brown (red bar) and grey (grey bar) offspring colour morphs produced by different combinations of parental colour morphs (B×B, B×G and G×G). The first columns show the observations in the field, second, third and fourth columns show the expected number of offspring colour morphs according to models with brown dominance, grey dominance and an additive genetic model, respectively. The lines above the bars show a G-test of association between models and their significance (NS: P=0.58, **P<0.002, ***P<0.0001).
Mentions: The model assuming brown dominance (Supplementary Table S1) produces a ratio of brown/grey phenotypes that almost exactly matches what is expected under this inheritance model in Hardy–Weinberg equilibrium (52.8% of offsprings are observed and 55.2% are expected to be brown, G1=0.308, P=0.58; Fig. 2, Supplementary Table S2). Repeating the above, but assuming that the allele for grey morph is dominant over the allele for brown produces a poorer fit between observed and expected ratio of the offspring (G2=12.98, P=0.0015; Fig. 2). There are more brown offspring observed than expected when assuming full dominance of the grey allele over brown. The purely additive model also fitted the data poorly. In this particular case, the colour scores of the adults were such that the additive model predicted that all offspring from monomorphic crosses were the same morph as the parents; thus, these crosses are not informative for testing. However, focusing on the heteromorphic (BxG) cross, it is clear that there are more offspring of the brown morph observed than expected also under the assumption of an additive genetic inheritance (G1=70.9, P<0.0001; Fig. 2). Alternative approaches for statistically comparing the observed and expected frequencies of morphs all provided the same conclusion (Supplementary Information). We thus conclude from the above exercises on the basis of comparing fledglings' morphs with their parents' morphs that we find evidence for genetic dominance of brown over grey, whereas dominance of grey and purely additive genetic effects are not supported by this data. Although this modelling is not exhaustive, it does show that the tawny owl phenotypic morph has a genetic architecture that relies on few genes with large effects, which is consistent with a Mendelian inheritance of colouration based on one locus with a 'brown' allele dominant over a 'grey' allele.

Bottom Line: As winter conditions became milder in the last decades, selection against the brown morph diminished.Concurrent with this reduced selection, the frequency of brown morphs increased rapidly in our study population during the last 28 years and nationwide during the last 48 years.Hence, we show the first evidence that recent climate change alters natural selection in a wild population leading to a microevolutionary response, which demonstrates the ability of wild populations to evolve in response to climate change.

View Article: PubMed Central - PubMed

Affiliation: Bird Ecology Unit, Department of Biosciences, University of Helsinki, PO Box 65 (Viikinkaari 1), Helsinki FI-00014, Finland. patrik.karell@helsinki.fi

ABSTRACT
To ensure long-term persistence, organisms must adapt to climate change, but an evolutionary response to a quantified selection pressure driven by climate change has not been empirically demonstrated in a wild population. Here, we show that pheomelanin-based plumage colouration in tawny owls is a highly heritable trait, consistent with a simple Mendelian pattern of brown (dark) dominance over grey (pale). We show that strong viability selection against the brown morph occurs, but only under snow-rich winters. As winter conditions became milder in the last decades, selection against the brown morph diminished. Concurrent with this reduced selection, the frequency of brown morphs increased rapidly in our study population during the last 28 years and nationwide during the last 48 years. Hence, we show the first evidence that recent climate change alters natural selection in a wild population leading to a microevolutionary response, which demonstrates the ability of wild populations to evolve in response to climate change.

Show MeSH
Related in: MedlinePlus