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Evolutionary pets: offspring numbers reveal speciation process in domesticated chickens.

Tiemann I, Rehkämper G - PLoS ONE (2012)

Bottom Line: We want to forward the question to the animal itself: With whom do you reproduce successfully?Due to selection and mate choice we state that breeding in principle can generate new species.Therefore, we see domestication as an evolutionary process that integrates human interests of animal breeding with innate mate choice by the animal.

View Article: PubMed Central - PubMed

Affiliation: Bruno-Dürigen Institute, Poultry Research Centre, Rommerskirchen, Germany. tiemanni@uni-duesseldorf.de

ABSTRACT
Since Darwin, the nature of the relationship between evolution and domestication has been debated. Evolution offers different mechanisms of selection that lead to adaptation and may end in the origin of new species as defined by the biological species concept. Domestication has given rise to numerous breeds in almost every domesticated species, including chickens. At the same time, so-called artificial selection seems to exclude mechanisms of sexual selection by the animals themselves. We want to forward the question to the animal itself: With whom do you reproduce successfully? This study focused on the sexual behavior of the domestic chicken Gallus gallus f.dom., particularly the White Crested Polish breed. Experiments on mate choice and the observation of fertilization and hatching rates of mixed-breeding groups revealed breed-specific preferences. In breeding groups containing White Crested Polish and a comparative breed, more purebred chicks hatched than hybrids (number of eggs collected: 1059). Mating was possible in equal shares, but in relation to the number of eggs collected, purebred offspring (62.75% ± 7.10%, M ± SE) hatched to a greater extend compared to hybrid offspring (28.75% ± 15.32%, M ± SE). These data demonstrate that the mechanism of sexual selection is still present in domestic chicken breeds, which includes the alteration of gene frequencies typical for domestication and evolutionary speciation. Due to selection and mate choice we state that breeding in principle can generate new species. Therefore, we see domestication as an evolutionary process that integrates human interests of animal breeding with innate mate choice by the animal.

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Portrait of a cock of the breed White Crested Polish.
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pone-0041453-g002: Portrait of a cock of the breed White Crested Polish.

Mentions: To answer these questions we designed an experiment, using a special breed of the domestic chicken, which we have investigated in previous studies, the Polish (US) or Poland (GB) chicken (more detailed, the White Crested Black Polish, WCP, figures 1 and 2). Darwin, as early as 1868, published a drawing highlighting the outer appearance of the Polish breed. Today the breed can be traced back to roman times [30]. In this breed the comb has been drastically reduced and is hardly visible in the male as well as in the female. Striking is the crest, which is a feathery balloon situated upon a bony protuberance of the skull. Also striking is the extraordinary large brain and characteristic brain composition [31], [32]. Particularly, the crest is the breeder's focus, who selects for this trait according to a standard of perfection, for example, the “Standard of Perfection of the American Poultry Association (US)”, the “British Poultry Standards (GB)”, and “Rassegeflügelstandard für Europa (Germany)”.


Evolutionary pets: offspring numbers reveal speciation process in domesticated chickens.

Tiemann I, Rehkämper G - PLoS ONE (2012)

Portrait of a cock of the breed White Crested Polish.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3412861&req=5

pone-0041453-g002: Portrait of a cock of the breed White Crested Polish.
Mentions: To answer these questions we designed an experiment, using a special breed of the domestic chicken, which we have investigated in previous studies, the Polish (US) or Poland (GB) chicken (more detailed, the White Crested Black Polish, WCP, figures 1 and 2). Darwin, as early as 1868, published a drawing highlighting the outer appearance of the Polish breed. Today the breed can be traced back to roman times [30]. In this breed the comb has been drastically reduced and is hardly visible in the male as well as in the female. Striking is the crest, which is a feathery balloon situated upon a bony protuberance of the skull. Also striking is the extraordinary large brain and characteristic brain composition [31], [32]. Particularly, the crest is the breeder's focus, who selects for this trait according to a standard of perfection, for example, the “Standard of Perfection of the American Poultry Association (US)”, the “British Poultry Standards (GB)”, and “Rassegeflügelstandard für Europa (Germany)”.

Bottom Line: We want to forward the question to the animal itself: With whom do you reproduce successfully?Due to selection and mate choice we state that breeding in principle can generate new species.Therefore, we see domestication as an evolutionary process that integrates human interests of animal breeding with innate mate choice by the animal.

View Article: PubMed Central - PubMed

Affiliation: Bruno-Dürigen Institute, Poultry Research Centre, Rommerskirchen, Germany. tiemanni@uni-duesseldorf.de

ABSTRACT
Since Darwin, the nature of the relationship between evolution and domestication has been debated. Evolution offers different mechanisms of selection that lead to adaptation and may end in the origin of new species as defined by the biological species concept. Domestication has given rise to numerous breeds in almost every domesticated species, including chickens. At the same time, so-called artificial selection seems to exclude mechanisms of sexual selection by the animals themselves. We want to forward the question to the animal itself: With whom do you reproduce successfully? This study focused on the sexual behavior of the domestic chicken Gallus gallus f.dom., particularly the White Crested Polish breed. Experiments on mate choice and the observation of fertilization and hatching rates of mixed-breeding groups revealed breed-specific preferences. In breeding groups containing White Crested Polish and a comparative breed, more purebred chicks hatched than hybrids (number of eggs collected: 1059). Mating was possible in equal shares, but in relation to the number of eggs collected, purebred offspring (62.75% ± 7.10%, M ± SE) hatched to a greater extend compared to hybrid offspring (28.75% ± 15.32%, M ± SE). These data demonstrate that the mechanism of sexual selection is still present in domestic chicken breeds, which includes the alteration of gene frequencies typical for domestication and evolutionary speciation. Due to selection and mate choice we state that breeding in principle can generate new species. Therefore, we see domestication as an evolutionary process that integrates human interests of animal breeding with innate mate choice by the animal.

Show MeSH