Environment and Poultry Breeding Problems

Gowe, R. S.; Robertson, Alan; Latter, B. D. H.

doi:10.3382/ps.0380462

Cited by 144 publications

(43 citation statements)

References 4 publications

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“…The benefit of this scheme over that from Gowe et al (1959) is decreased as r fm gets larger. For sex-linked loci, a benefit is also produced if males are the heterogametic sex.…”

Section: Effective Population Size In Conservation Practicesmentioning

confidence: 99%

“…However, effective sizes 42N can actually be obtained by population subdivision (Wright, 1943;Wang and Caballero, 1999) and other strategies, as shown below. The extension of the strategy in the case of different numbers of males and females was developed by Gowe et al (1959). In their selection scheme, each male contributes one son and r fm = N f /N m daughters, and each female contributes one daughter and has a probability of…”

Section: Effective Population Size In Conservation Practicesmentioning

confidence: 99%

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Prediction and estimation of effective population size

2016

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Effective population size (N e ) is a key parameter in population genetics. It has important applications in evolutionary biology, conservation genetics and plant and animal breeding, because it measures the rates of genetic drift and inbreeding and affects the efficacy of systematic evolutionary forces, such as mutation, selection and migration. We review the developments in predictive equations and estimation methodologies of effective size. In the prediction part, we focus on the equations for populations with different modes of reproduction, for populations under selection for unlinked or linked loci and for the specific applications to conservation genetics. In the estimation part, we focus on methods developed for estimating the current or recent effective size from molecular marker or sequence data. We discuss some underdeveloped areas in predicting and estimating N e for future research.Heredity ( INTRODUCTIONThe concept of effective population size, introduced by Sewall Wright (1931, 1933), is central to plant and animal breeding (Falconer and Mackay, 1996), conservation genetics (Frankham et al., 2010;Allendorf et al., 2013) and molecular variation and evolution (Charlesworth and Charlesworth, 2010), as it quantifies the magnitude of genetic drift and inbreeding in real-world populations. A substantial number of extensions to the basic theory and predictions were made since the seminal work of Wright, with main early developments by James Crow and Motoo Kimura (Kimura and Crow, 1963a;Crow and Kimura, 1970) and later by a list of contributors. Several review papers (Crow and Denniston, 1988;Caballero, 1994;Wang and Caballero, 1999;Nomura, 2005a) and population genetic books (Fisher, 1965;Wright, 1969;Ewens, 1979;Nagylaki, 1992) have summarised the existing theory in predicting the effective size of a population at different spatial and timescales under various inheritance modes and demographies. Comparatively, methodological developments (reviewed by Schwartz et al., 1999;Beaumont, 2003a;Wang, 2005;Palstra and Ruzzante, 2008;Luikart et al., 2010;Gilbert and Whitlock, 2015) in estimating the effective size of natural populations from genetic data lag behind but are accelerating in the past decade, thanks to the rapid developments of molecular biology.The classical developments of effective population size theory are based on the rate of change in gene frequency variance (genetic drift) or the rate of inbreeding. The effective population size is defined in reference to the Wright-Fisher idealised population, that is, a hypothetical population with very simplifying characteristics where genetic drift is the only factor in operation, and the dynamics of allelic and genotypic frequencies across generations merely depend on the population census (N) size. The effective size of a real population is then defined as the size of an idealised population, which would give rise to the rate of inbreeding and the rate of change in variance of gene frequencies actually observed in the population under consideration,

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“…The benefit of this scheme over that from Gowe et al (1959) is decreased as r fm gets larger. For sex-linked loci, a benefit is also produced if males are the heterogametic sex.…”

Section: Effective Population Size In Conservation Practicesmentioning

confidence: 99%

Section: Effective Population Size In Conservation Practicesmentioning

confidence: 99%

Prediction and estimation of effective population size

2016

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“…In such a scheme, both population size and sex ratio are kept constant. Gowe et al (1959) proposed a procedure that reduces to selecting one female from each full-sib family and one male from each half-sib sire family. Consequently, each dam contributes a single female offspring, but one of the dams mated to each sire also contributes a male.…”

Section: Managing the Contributions Of Individualsmentioning

confidence: 99%

Management of genetic diversity in small farm animal populations

Fernández

Meuwissen

Toro

et al. 2011

Animal

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Many local breeds of farm animals have small populations and, consequently, are highly endangered. The correct genetic management of such populations is crucial for their survival. Managing an animal population involves two steps: first, the individuals who will be permitted to leave descendants are to be chosen and the number offspring they will be permitted to produce has to be determined; second, the mating scheme has to be identified. Strategies dealing with the first step are directed towards the maximisation of effective population size and, therefore, act jointly on the reduction in the loss of genetic variation and in the increase of inbreeding. In this paper, the most relevant methods are summarised, including the so-called 'Optimum Contribution' methodology (contributions are proportional to the coancestry of each individual with the rest), which has been shown to be the best. Typically, this method is applied to pedigree information, but molecular marker data can be used to complete or replace the genealogy. When the population is subjected to explicit selection on any trait, the above methodology can be used by balancing the response to selection and the increase in coancestry/inbreeding. Different mating strategies also exist. Some of the mating schemes try to reduce the level of inbreeding in the short term by preventing mating between relatives. Others involve regular (circular) schemes that imply higher levels of inbreeding within populations in the short term, but demonstrate better performance in the long term. In addition, other tools such as cryopreservation and reproductive techniques aid in the management of small populations. In the future, genomic marker panels may replace the pedigree information in measuring the coancestry. The paper also includes the results of several experiments and field studies on the effectiveness and on the consequences of the use of the different strategies.

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“…I also propose a mating scheme, under which the effective size is increased whereas the inbreeding coefficient is decreased in any generation compared with those under random mating. I will show that the newly proposed breeding system could increase the effective size by as much as 19 per cent for autosomal loci and 50 per cent for sex-linked loci compared with the breeding system of Gowe et al (1959).…”

Section: Introductionmentioning

confidence: 99%

“…When the sexes are unequal in 591 numbers, as is usually the case in domestic animals, Gowe et al (1959) proposed a selection scheme for control populations. In this design, each male has one son and FIM daughters, and each female has one daughter and a probability of MIF of having one son, where M and F are the numbers of males and females, respectively.…”

Section: Introductionmentioning

confidence: 99%

More efficient breeding systems for controlling inbreeding and effective size in animal populations

Wang

1997

Heredity

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A selection scheme and a mating scheme are proposed to control the inbreeding and genetic drift in conserved or control animal populations with different numbers of males and females. Recurrence equations for the inbreeding coefficient and formulae for effective size are derived for autosomal loci, sex-linked loci with males being heterogametic and sex-linked loci with females being heterogametic under each of four breeding systems. It is shown that both the selection scheme and the mating scheme proposed in this paper could increase the effective size and decrease inbreeding in any generation compared with the classical selection and mating schemes. Among the four breeding systems considered, the most efficient one could increase the effective size by as much as 19 per cent for autosomal loci and 50 per cent for sex-linked loci in comparison with the classical breeding system usually utilized in conserved or control populations.

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Environment and Poultry Breeding Problems

Cited by 144 publications

References 4 publications

Prediction and estimation of effective population size

Prediction and estimation of effective population size

Management of genetic diversity in small farm animal populations

More efficient breeding systems for controlling inbreeding and effective size in animal populations

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