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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 Lohmann Selected Leghorn Classic.
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Related In: Results  -  Collection


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pone-0041453-g006: Portrait of a cock of the breed Lohmann Selected Leghorn Classic.

Mentions: Four mixed breeding groups were established, each of the four breeding groups contained three female WCPs and three Red Leghorns (RL, year 1, figure 5) or Lohmann Selected Leghorns (LSL, year 2; see figure 6). In two of the four groups a WCP cock joined the hens; in the other two groups a cock of the comparative breed was added (group a and b in table 1). All animals were incubated, hatched and raised together to ensure that life-history and social as well as external experiences did not influence the collected samples. Moreover, animal numbers in terms of sex and breed were kept equal throughout the experimental prehistory. Each group was kept in a small chicken house (W×D×H: 120×120×190 cm) containing perches and a brood nest. Each chicken house was located on a meadow of 250 m2. Water, commercial chicken food, and grit were provided ad libitum.


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

Tiemann I, Rehkämper G - PLoS ONE (2012)

Portrait of a cock of the breed Lohmann Selected Leghorn Classic.
© Copyright Policy
Related In: Results  -  Collection

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

pone-0041453-g006: Portrait of a cock of the breed Lohmann Selected Leghorn Classic.
Mentions: Four mixed breeding groups were established, each of the four breeding groups contained three female WCPs and three Red Leghorns (RL, year 1, figure 5) or Lohmann Selected Leghorns (LSL, year 2; see figure 6). In two of the four groups a WCP cock joined the hens; in the other two groups a cock of the comparative breed was added (group a and b in table 1). All animals were incubated, hatched and raised together to ensure that life-history and social as well as external experiences did not influence the collected samples. Moreover, animal numbers in terms of sex and breed were kept equal throughout the experimental prehistory. Each group was kept in a small chicken house (W×D×H: 120×120×190 cm) containing perches and a brood nest. Each chicken house was located on a meadow of 250 m2. Water, commercial chicken food, and grit were provided ad libitum.

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