Inbreeding – lessons from animal breeding, evolutionary biology and conservation genetics

2005 ◽  
Vol 80 (2) ◽  
pp. 121-133 ◽  
Author(s):  
T. N. Kristensen ◽  
A. C. Sørensen
Keyword(s):  
Conservation Genetics ◽  
Evolutionary Biology ◽  
Animal Breeding ◽  
Experimental Literature ◽  
Genetic Progress ◽  
Environmental Variance ◽  
Deleterious Alleles ◽  
Variable Nature ◽  
Breeding Programmes

Abstract Increased rates of inbreeding are one side effect of breeding programmes designed to give genetic progress for traits of economic importance in livestock. Inbreeding leads to inbreeding depression for traits showing dominance, and will ultimately lead to a decrease in genetic variance within populations. Here we review theoretical and experimental literature from animal breeding, evolutionary biology and conservation genetics on the consequences of inbreeding in terms of trait means and genetic and environmental variance components. The genetic background for these effects is presented and the experimental literature interpreted in relation to them. Furthermore, purging of deleterious alleles and the variable nature of effects of inbreeding on populations are discussed. Based on the literature, we conclude that inbreeding in animal breeding must be controlled very efficiently to maintain long-term sustainable livestock production in the future. The tools to do this efficiently exist, and much can be learnt on inbreeding from the literature in fields only distantly related to animal breeding.

scholarly journals Long-term exhaustion of the inbreeding load in Drosophila melanogaster

Heredity ◽  
2021 ◽  
Author(s):  
Noelia Pérez-Pereira ◽  
Ramón Pouso ◽  
Ana Rus ◽  
Ana Vilas ◽  
Eugenio López-Cortegano ◽  
...  
Keyword(s):  
Inbreeding Depression ◽  
Evolutionary Biology ◽  
Gene Action ◽  
Large Population ◽  
Recessive Gene ◽  
Deleterious Alleles ◽  
Sib Mating ◽  
Large Populations ◽  
Great Relevance

AbstractInbreeding depression, the decline in fitness of inbred individuals, is a ubiquitous phenomenon of great relevance in evolutionary biology and in the fields of animal and plant breeding and conservation. Inbreeding depression is due to the expression of recessive deleterious alleles that are concealed in heterozygous state in noninbred individuals, the so-called inbreeding load. Genetic purging reduces inbreeding depression by removing these alleles when expressed in homozygosis due to inbreeding. It is generally thought that fast inbreeding (such as that generated by full-sib mating lines) removes only highly deleterious recessive alleles, while slow inbreeding can also remove mildly deleterious ones. However, a question remains regarding which proportion of the inbreeding load can be removed by purging under slow inbreeding in moderately large populations. We report results of two long-term slow inbreeding Drosophila experiments (125–234 generations), each using a large population and a number of derived lines with effective sizes about 1000 and 50, respectively. The inbreeding load was virtually exhausted after more than one hundred generations in large populations and between a few tens and over one hundred generations in the lines. This result is not expected from genetic drift alone, and is in agreement with the theoretical purging predictions. Computer simulations suggest that these results are consistent with a model of relatively few deleterious mutations of large homozygous effects and partially recessive gene action.

scholarly journals Evolutionary Stability for Interactions among Kin under Quantitative Inheritance.

Genetics ◽  
1989 ◽  
Vol 121 (4) ◽  
pp. 877-889
Author(s):  
A B Harper
Keyword(s):  
Inclusive Fitness ◽  
Fitness Function ◽  
Quantitative Inheritance ◽  
Evolutionarily Stable Strategies ◽  
Environmental Variance ◽  
Pairwise Interactions ◽  
Simplifying Assumptions ◽  
Multilocus Model ◽  
Evolutionarily Stable

Abstract The theory of evolutionarily stable strategies (ESS) predicts the long-term evolutionary outcome of frequency-dependent selection by making a number of simplifying assumptions about the genetic basis of inheritance. I use a symmetrized multilocus model of quantitative inheritance without mutation to analyze the results of interactions between pairs of related individuals and compare the equilibria to those found by ESS analysis. It is assumed that the fitness changes due to interactions can be approximated by the exponential of a quadratic surface. The major results are the following. (1) The evolutionarily stable phenotypes found by ESS analysis are always equilibria of the model studied here. (2) When relatives interact, one of the two conditions for stability of equilibria differs between the two models; this can be accounted for by positing that the inclusive fitness function for quantitative characters is slightly different from the inclusive fitness function for characters determined by a single locus. (3) The inclusion of environmental variance will in general change the equilibrium phenotype, but the equilibria of ESS analysis are changed to the same extent by environmental variance. (4) A class of genetically polymorphic equilibria occur, which in the present model are always unstable. These results expand the range of conditions under which one can validly predict the evolution of pairwise interactions using ESS analysis.

scholarly journals The heritable landscape of near-infrared and Raman spectroscopic measurements to improve lipid content in Atlantic salmon fillets

2021 ◽  
Vol 53 (1) ◽  
Author(s):  
Gareth F. Difford ◽  
Siri S. Horn ◽  
Katinka R. Dankel ◽  
Bente Ruyter ◽  
Binyam S. Dagnachew ◽  
...  
Keyword(s):  
Atlantic Salmon ◽  
Lipid Content ◽  
Production Efficiency ◽  
Near Infrared ◽  
Reference Method ◽  
Partial Least Square ◽  
Least Square ◽  
Genetic Management ◽  
Genetic Progress ◽  
Breeding Programmes

Abstract Background Product quality and production efficiency of Atlantic salmon are, to a large extent, influenced by the deposition and depletion of lipid reserves. Fillet lipid content is a heritable trait and is unfavourably correlated with growth, thus genetic management of fillet lipid content is needed for sustained genetic progress in these two traits. The laboratory-based reference method for recording fillet lipid content is highly accurate and precise but, at the same time, expensive, time-consuming, and destructive. Here, we test the use of rapid and cheaper vibrational spectroscopy methods, namely near-infrared (NIR) and Raman spectroscopy both as individual phenotypes and phenotypic predictors of lipid content in Atlantic salmon. Results Remarkably, 827 of the 1500 individual Raman variables (i.e. Raman shifts) of the Raman spectrum were significantly heritable (heritability (h2) ranging from 0.15 to 0.65). Similarly, 407 of the 2696 NIR spectral landscape variables (i.e. wavelengths) were significantly heritable (h2 = 0.27–0.40). Both Raman and NIR spectral landscapes had significantly heritable regions, which are also informative in spectroscopic predictions of lipid content. Partial least square predicted lipid content using Raman and NIR spectra were highly concordant and highly genetically correlated with the lipid content values ($${r}_{\text{g}}$$ r g = 0.91–0.98) obtained with the reference method using Lin’s concordance correlation coefficient (CCC = 0.63–0.90), and were significantly heritable ($${h}^{2}$$ h 2 = 0.52–0.67). Conclusions Both NIR and Raman spectral landscapes show substantial additive genetic variation and are highly genetically correlated with the reference method. These findings lay down the foundation for rapid spectroscopic measurement of lipid content in salmonid breeding programmes.

Mass extinctions alter extinction and origination dynamics with respect to body size

2021 ◽  
Vol 288 (1960) ◽  
Author(s):  
Pedro M. Monarrez ◽  
Noel A. Heim ◽  
Jonathan L. Payne
Keyword(s):  
Body Size ◽  
Mass Extinction ◽  
Evolutionary Biology ◽  
Marine Animal ◽  
Mass Extinctions ◽  
Extinction Selectivity ◽  
Extinction Events ◽  
Mass Extinction Events ◽  
Marine Biosphere

Whether mass extinctions and their associated recoveries represent an intensification of background extinction and origination dynamics versus a separate macroevolutionary regime remains a central debate in evolutionary biology. The previous focus has been on extinction, but origination dynamics may be equally or more important for long-term evolutionary outcomes. The evolution of animal body size is an ideal process to test for differences in macroevolutionary regimes, as body size is easily determined, comparable across distantly related taxa and scales with organismal traits. Here, we test for shifts in selectivity between background intervals and the ‘Big Five’ mass extinction events using capture–mark–recapture models. Our body-size data cover 10 203 fossil marine animal genera spanning 10 Linnaean classes with occurrences ranging from Early Ordovician to Late Pleistocene (485–1 Ma). Most classes exhibit differences in both origination and extinction selectivity between background intervals and mass extinctions, with the direction of selectivity varying among classes and overall exhibiting stronger selectivity during origination after mass extinction than extinction during the mass extinction. Thus, not only do mass extinction events shift the marine biosphere into a new macroevolutionary regime, the dynamics of recovery from mass extinction also appear to play an underappreciated role in shaping the biosphere in their aftermath.

scholarly journals ESTIMATION OF SOME GENETIC PRAMETERS IN DURUM WHEAT

2017 ◽  
Vol 48 (2) ◽  
Author(s):  
Almajidy & et al.
Keyword(s):  
Grain Yield ◽  
Durum Wheat ◽  
Harvest Index ◽  
Agricultural Research ◽  
Block Design ◽  
Selection Index ◽  
Research Station ◽  
Genetic Progress ◽  
Environmental Variance ◽  
High Heritability

To estimate genetic parameters and heritability in durum wheat (Triticum turgidum var. durum) genotypes, seventeen genotypes (16 exotic from ICARDA and local variety (Buhooth 7)) were included in this study. This experiment was conducted using a randomized complete block design with three replications at Field Crops Research Station, Abu-Graib, Office of Agricultural Research, during 2011-2012 and 2012-2013. The results revealed significant differences among genotypes for the studied characters at both seasons. The best genetic/environmental variance ratio attained for spike length (11.90) and no. of spikes. m-2 (9.22) in the first season, and grain yield (8.82) then harvest index (4.87) in the second season. High GCV observed for grain yield (15.68), no. of spikes. m-2 (15.18) in the first season, and harvest index (16.89) and grain yield (14.22) in the second season. High heritability estimates associated with high genetic advance for no. of spikes. m-2, in the first season. While, moderate h2bs estimates associated with high GA for same trait in the second season. Expected response to selection ranged from 0.93 to 84.6, also selection index ranged from 1.23 to 106.44 for grain yield and number of spikes. m-2, respectively in the first season also the same pattern was observed for value of second season. Characteristics like no. of spikes. m-2, plant height, no. of grains. Spike-1 and grain weight showed high heritability coupled with high genetic progress. Therefore, these characters should be given top priority during selection breeding in durum wheat.

scholarly journals Fluctuating selection: the perpetual renewal of adaptation in variable environments

2010 ◽  
Vol 365 (1537) ◽  
pp. 87-97 ◽  
Author(s):  
Graham Bell
Keyword(s):  
Natural Selection ◽  
Evolutionary Biology ◽  
Natural Populations ◽  
Phenotypic Variance ◽  
Weak Selection ◽  
Fluctuating Selection ◽  
Environmental Variance ◽  
Strong Selection ◽  
Genomic Studies ◽  
Over Time

Darwin insisted that evolutionary change occurs very slowly over long periods of time, and this gradualist view was accepted by his supporters and incorporated into the infinitesimal model of quantitative genetics developed by R. A. Fisher and others. It dominated the first century of evolutionary biology, but has been challenged in more recent years both by field surveys demonstrating strong selection in natural populations and by quantitative trait loci and genomic studies, indicating that adaptation is often attributable to mutations in a few genes. The prevalence of strong selection seems inconsistent, however, with the high heritability often observed in natural populations, and with the claim that the amount of morphological change in contemporary and fossil lineages is independent of elapsed time. I argue that these discrepancies are resolved by realistic accounts of environmental and evolutionary changes. First, the physical and biotic environment varies on all time-scales, leading to an indefinite increase in environmental variance over time. Secondly, the intensity and direction of natural selection are also likely to fluctuate over time, leading to an indefinite increase in phenotypic variance in any given evolving lineage. Finally, detailed long-term studies of selection in natural populations demonstrate that selection often changes in direction. I conclude that the traditional gradualist scheme of weak selection acting on polygenic variation should be supplemented by the view that adaptation is often based on oligogenic variation exposed to commonplace, strong, fluctuating natural selection.

Cutthroat Trout: Evolutionary Biology and Taxonomy

2018 ◽  
Keyword(s):  
Evolutionary Biology ◽  
Species Concept ◽  
Management Strategies ◽  
Cutthroat Trout ◽  
Ecological Processes ◽  
Oncorhynchus Clarkii ◽  
Voucher Specimens ◽  
Captive Propagation ◽  
Analytical Tools

<em>Abstract</em>.—The broad distribution and regional variation of Cutthroat Trout <em>Oncorhynchus clarkii </em>across western North America has led to considerable interest in the different forms from both scientific and recreational perspectives. This volume represents an attempt to describe this observed diversity with the most current information available and suggests a revised taxonomy for Cutthroat Trout. However, what is proposed in this volume will be subject to change or refinement as new techniques and analytical tools become available. In particular, remaining uncertainty would benefit from a comparison of all described lineages with a common set of morphological and genetic markers. A range-wide collection of voucher specimens will help to document variation in these characteristics, and we encourage field biologists to prioritize these collections. Future revisions will benefit from agreement on a species concept and explicitly state the assumptions of the chosen species concept. We encourage collaboration between managers and taxonomists to accurately delineate units of conservation that can be used by decision makers tasked with ensuring the long-term persistence of Cutthroat Trout lineages. The proposed taxonomic revisions herein validate many of the ongoing management strategies to conserve Cutthroat Trout, but we advise additional consideration of life-history diversity as an attainable management target. For long-term persistence of all Cutthroat Trout, maintaining and expanding the availability of high quality, well-connected stream and lake habitats will be a necessary first step to achieving desired conservation outcomes. Moreover, restoring and protecting ecological processes are key to conserving the diversity found within and among lineages of Cutthroat Trout. In systems where native Cutthroat Trout have been extirpated or suppressed, captive propagation and translocation are two potentially available tools to re-establish or reinvigorate populations. Last, we encourage fisheries managers and taxonomists to embrace the challenges that come with conserving locally unique forms of wide-ranging species like Cutthroat Trout.

Poultry breeding for sustainability and welfare.

2020 ◽  
pp. 117-146
Author(s):  
Anne-Marie Neeteson ◽  
Santiago Avendaño ◽  
Alfons Koerhuis
Keyword(s):  
Body Composition ◽  
Environmental Impact ◽  
Economic Impact ◽  
Food Chain ◽  
Genetic Improvement ◽  
Animal Breeding ◽  
Animal Populations ◽  
Poultry Breeding ◽  
Programme Design

Abstract Animal breeding for welfare and sustainability requires improving and optimizing environmental impact, productivity, robustness and welfare. Breeding is a long-term exercise at the start of the food chain with permanent cumulative outcomes, disseminated widely. This chapter explains, with a focus on poultry, breeding programme design and how broadening breeding goals and managing trait antagonism results in balanced breeding and more robust animal populations. Breeding progress in skeleton and skin health, physiology and body composition, and behaviour are addressed. The economic impact of welfare and environmental improvements is worked out, and the ethical and societal aspects of genetic improvement are put into perspective. The consideration of feedbacks of all stakeholders, including customers and the wider society, is crucial. For each crossbreed, breeders will continue to improve overall welfare, health, productivity and environmental impact, but between the crossbreeds there will be clear differences answering specific demands of concepts and brands.

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