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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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Temporal changes in the frequency of the brown morph in Finland on different scales.(a) Historical data on colour morph frequencies in the early century (1911–1945) and mid-century (1946–1980) based on skins from the Zoological museum collection (University of Helsinki). Each symbol represents the mean frequencies of seven 5-year periods (± s.e.m.). (b) Frequency of the brown morph in the study population based on captured breeding birds between 1981 and 2008. Shown are mean annual frequencies of the brown morph in 5-year periods (±s.e.m.). (c) Nationwide population frequency of brown individuals based on all breeding birds ringed or recaptured by amateur ringers in Finland and colour scored as either grey or brown. Symbols are as in b. Total sample size is given along the x axis. The method of scoring colour morphs in a and b (filled diamonds) differs from the method used in c (filled dots), such that the averages and slope of the trend are not directly comparable, although the direction is.
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f4: Temporal changes in the frequency of the brown morph in Finland on different scales.(a) Historical data on colour morph frequencies in the early century (1911–1945) and mid-century (1946–1980) based on skins from the Zoological museum collection (University of Helsinki). Each symbol represents the mean frequencies of seven 5-year periods (± s.e.m.). (b) Frequency of the brown morph in the study population based on captured breeding birds between 1981 and 2008. Shown are mean annual frequencies of the brown morph in 5-year periods (±s.e.m.). (c) Nationwide population frequency of brown individuals based on all breeding birds ringed or recaptured by amateur ringers in Finland and colour scored as either grey or brown. Symbols are as in b. Total sample size is given along the x axis. The method of scoring colour morphs in a and b (filled diamonds) differs from the method used in c (filled dots), such that the averages and slope of the trend are not directly comparable, although the direction is.

Mentions: When selection on a heritable trait changes, a response in the composition of the population is expected19. We indeed found that the frequency of brown morphs increased markedly between 1981 and 2008. Compared with historical data, when on average one-third of the individuals were brown (Fig. 4a), we found that the brown morph rapidly increased in frequency especially during the last decade (Fig. 4b; binomial generalized linear model 1981–2008, year: b=0.050±0.009 s.e.m., z=5.66, N=28, P<0.0001). This phenotypic change was present also on a larger nationwide scale. In a time series of tawny owls captured, marked and colour scored (grey or brown) by ornithologists all over Finland between 1961 and 2008 (N=3,239 observations), we found a steadily increasing frequency of the brown morph (Fig. 4c, year: b=0.025±0.004 s.e.m., z=6.94, N=48, P<0.0001). Thus, the increase of the brown morph is a large scale phenomenon occurring all over Finland, involving thousands of individuals. Hence, this phenotypic change is unlikely to be caused by genetic drift, because drift is only a major force for changing allele frequencies in small populations. Given the strong genetic underpinning of tawny owl morphs (see above), we consider the observed phenotypic trend in the proportion of the brown morph as indicative for a shift in gene frequencies. Hence, we here document microevolution of tawny owl plumage colour.


Climate change drives microevolution in a wild bird.

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

Temporal changes in the frequency of the brown morph in Finland on different scales.(a) Historical data on colour morph frequencies in the early century (1911–1945) and mid-century (1946–1980) based on skins from the Zoological museum collection (University of Helsinki). Each symbol represents the mean frequencies of seven 5-year periods (± s.e.m.). (b) Frequency of the brown morph in the study population based on captured breeding birds between 1981 and 2008. Shown are mean annual frequencies of the brown morph in 5-year periods (±s.e.m.). (c) Nationwide population frequency of brown individuals based on all breeding birds ringed or recaptured by amateur ringers in Finland and colour scored as either grey or brown. Symbols are as in b. Total sample size is given along the x axis. The method of scoring colour morphs in a and b (filled diamonds) differs from the method used in c (filled dots), such that the averages and slope of the trend are not directly comparable, although the direction is.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

f4: Temporal changes in the frequency of the brown morph in Finland on different scales.(a) Historical data on colour morph frequencies in the early century (1911–1945) and mid-century (1946–1980) based on skins from the Zoological museum collection (University of Helsinki). Each symbol represents the mean frequencies of seven 5-year periods (± s.e.m.). (b) Frequency of the brown morph in the study population based on captured breeding birds between 1981 and 2008. Shown are mean annual frequencies of the brown morph in 5-year periods (±s.e.m.). (c) Nationwide population frequency of brown individuals based on all breeding birds ringed or recaptured by amateur ringers in Finland and colour scored as either grey or brown. Symbols are as in b. Total sample size is given along the x axis. The method of scoring colour morphs in a and b (filled diamonds) differs from the method used in c (filled dots), such that the averages and slope of the trend are not directly comparable, although the direction is.
Mentions: When selection on a heritable trait changes, a response in the composition of the population is expected19. We indeed found that the frequency of brown morphs increased markedly between 1981 and 2008. Compared with historical data, when on average one-third of the individuals were brown (Fig. 4a), we found that the brown morph rapidly increased in frequency especially during the last decade (Fig. 4b; binomial generalized linear model 1981–2008, year: b=0.050±0.009 s.e.m., z=5.66, N=28, P<0.0001). This phenotypic change was present also on a larger nationwide scale. In a time series of tawny owls captured, marked and colour scored (grey or brown) by ornithologists all over Finland between 1961 and 2008 (N=3,239 observations), we found a steadily increasing frequency of the brown morph (Fig. 4c, year: b=0.025±0.004 s.e.m., z=6.94, N=48, P<0.0001). Thus, the increase of the brown morph is a large scale phenomenon occurring all over Finland, involving thousands of individuals. Hence, this phenotypic change is unlikely to be caused by genetic drift, because drift is only a major force for changing allele frequencies in small populations. Given the strong genetic underpinning of tawny owl morphs (see above), we consider the observed phenotypic trend in the proportion of the brown morph as indicative for a shift in gene frequencies. Hence, we here document microevolution of tawny owl plumage colour.

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