Trends in genetic diversity and the effect of inbreeding in American Angus cattle under genomic selection

Abstract Background While the adoption of genomic evaluations in livestock has increased genetic gain rates, its effects on genetic diversity and accumulation of inbreeding have raised concerns in cattle populations. Increased inbreeding may affect fitness and decrease the mean performance for economically important traits, such as fertility and growth in beef cattle, with the age of inbreeding having a possible effect on the magnitude of inbreeding depression. The purpose of this study was to determine changes in genetic diversity as a result of the implementation of genomic selection in Angus cattle and quantify potential inbreeding depression effects of total pedigree and genomic inbreeding, and also to investigate the impact of recent and ancient inbreeding. Results We found that the yearly rate of inbreeding accumulation remained similar in sires and decreased significantly in dams since the implementation of genomic selection. Other measures such as effective population size and the effective number of chromosome segments show little evidence of a detrimental effect of using genomic selection strategies on the genetic diversity of beef cattle. We also quantified pedigree and genomic inbreeding depression for fertility and growth. While inbreeding did not affect fertility, an increase in pedigree or genomic inbreeding was associated with decreased birth weight, weaning weight, and post-weaning gain in both sexes. We also measured the impact of the age of inbreeding and found that recent inbreeding had a larger depressive effect on growth than ancient inbreeding. Conclusions In this study, we sought to quantify and understand the possible consequences of genomic selection on the genetic diversity of American Angus cattle. In both sires and dams, we found that, generally, genomic selection resulted in decreased rates of pedigree and genomic inbreeding accumulation and increased or sustained effective population sizes and number of independently segregating chromosome segments. We also found significant depressive effects of inbreeding accumulation on economically important growth traits, particularly with genomic and recent inbreeding.

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30 Inbreeding in American Angus cattle before and after the implementation of genomic selection

Journal of Animal Science ◽

10.1093/jas/skaa278.026 ◽

2020 ◽

Vol 98 (Supplement_4) ◽

pp. 14-14

Author(s):

Emmanuel A Lozada-Soto ◽

Francesco Tiezzi ◽

Duc Lu ◽

Stephen P Miller ◽

John B Cole ◽

...

Keyword(s):

Genomic Selection ◽

Effective Population ◽

Generation Interval ◽

Inbreeding Coefficients ◽

Angus Cattle ◽

Before And After ◽

Population Sizes ◽

The Mean ◽

Time Periods ◽

Genomic Inbreeding

Abstract The aim of this study was to characterize the American Angus cattle population in terms of changes to the inbreeding rate (ΔF) and effective population size (Ne) before and after the implementation of genomic selection (GS). Genomic information (89,206 SNPs) was obtained for 25,960 bulls and 134,962 cows born between the years 2000 and 2017. Bulls and cows were independently grouped into two groups based on year of birth, pre-GS (2000–2009), and post-GS (2010–2017). Genomic inbreeding (FGRM) was calculated assuming fixed allele frequencies (0.5). Inbreeding based on runs of homozygosity (FROH) was calculated using software SNP1101 (Sargolzaei, 2014). The yearly ΔF for each group was estimated by regressing the inbreeding coefficients on year of birth. The generation intervals (L) were calculated for each of the four pathways of selection at both time periods (pre-GS and post-GS), where the mean of the sires of sires and dams of sires pathways was taken to be the generation interval for the bulls and the mean of the sires of dams and dams of dams pathways was taken to be the generation interval for the cows. The L and ΔF of the three inbreeding coefficients were used to estimate the Ne. Estimates of ΔF and Ne for both sexes at the two time periods can be found in table 1. In both sexes, ΔFROH decreased and NeROH increased from pre-GS to post-GS. For bulls, ΔFGRM and NeGRM did not change, and for cows, ΔFGRM decreased and NeGRM increased from pre-GS to post-GS. These results suggest that the implementation of genomic selection in Angus cattle has not caused the increased inbreeding rates and reduced effective population sizes seen in other species, but instead has been beneficial for the preservation of genetic diversity.

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Characterization of a haplotype- reference panel for genotyping by low-pass sequencing in Swiss Large White pigs

10.21203/rs.3.rs-318745/v1 ◽

2021 ◽

Author(s):

Adéla Nosková ◽

Meenu Bhati ◽

Naveen Kumar Kadri ◽

Danang Crysnanto ◽

Stefan Neuenschwander ◽

...

Keyword(s):

Genetic Diversity ◽

Principal Component ◽

Cost Effective ◽

Reference Panel ◽

Effective Population ◽

Large White ◽

Breeding Populations ◽

Low Pass ◽

Signatures Of Selection ◽

Genomic Inbreeding

Abstract Background The key-ancestor approach has been frequently applied to prioritize individuals for whole-genome sequencing based on their marginal genetic contribution to current populations. Using this approach, we selected 70 key ancestors from two lines of the Swiss Large White breed that have been selected divergently for fertility and fattening traits and sequenced their genomes with short paired-end reads. Results Using pedigree records, we estimated the effective population size of the dam and sire line to 72 and 44, respectively. In order to assess sequence variation in both lines, we sequenced the genomes of 70 boars at an average coverage of 16.69-fold. The boars explained 87.95 and 95.35% of the genetic diversity of the breeding populations of the dam and sire line, respectively. Reference-guided variant discovery using the GATK revealed 26,862,369 polymorphic sites. Principal component, admixture and FST analyses indicated considerable genetic differentiation between the lines. Genomic inbreeding quantified using runs of homozygosity was higher in the sire than dam line (0.28 vs 0.26). Using two complementary approaches (CLR and iHS), we detected 51 signatures of selection. However, only six signatures of selection overlapped between both lines. We used the sequenced haplotypes of the 70 key ancestors as a reference panel to call 22,618,811 genotypes in 175 pigs that had been sequenced at very low coverage (1.11-fold) using GLIMPSE. The genotype concordance, non-reference sensitivity and non-reference discrepancy between thus inferred and Illumina PorcineSNP60 BeadChip-called genotypes was 97.60, 98.73 and 3.24%, respectively. The low-pass sequencing-derived genomic relationship coefficients were highly correlated (r > 0.99) with those obtained from microarray genotyping. Conclusions We assessed genetic diversity within and between two lines of the Swiss Large White pig breed. Our analyses revealed considerable differentiation, even though the split into two populations occurred only few generations ago. The sequenced haplotypes of the key ancestor animals enabled us to implement genotyping by low-pass sequencing which offers an intriguing cost-effective approach to increase the variant density over current array-based genotyping by more than 350-fold.

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The Impact of Genetic Changes during Crop Domestication

Agronomy ◽

10.3390/agronomy8070119 ◽

2018 ◽

Vol 8 (7) ◽

pp. 119 ◽

Cited By ~ 38

Author(s):

Petr Smýkal ◽

Matthew Nelson ◽

Jens Berger ◽

Eric Von Wettberg

Keyword(s):

Genetic Diversity ◽

Genetic Variation ◽

Gene Pools ◽

Human Society ◽

Selective Sweeps ◽

Crop Domestication ◽

Effective Population ◽

Evolutionary Trajectory ◽

Nutrient Levels ◽

The Impact

Humans have domesticated hundreds of plant and animal species as sources of food, fiber, forage, and tools over the past 12,000 years, with manifold effects on both human society and the genetic structure of the domesticated species. The outcomes of crop domestication were shaped by selection driven by human preferences, cultivation practices, and agricultural environments, as well as other population genetic processes flowing from the ensuing reduction in effective population size. It is obvious that any selection imposes a reduction of diversity, favoring preferred genotypes, such as nonshattering seeds or increased palatability. Furthermore, agricultural practices greatly reduced effective population sizes of crops, allowing genetic drift to alter genotype frequencies. Current advances in molecular technologies, particularly of genome sequencing, provide evidence of human selection acting on numerous loci during and after crop domestication. Population-level molecular analyses also enable us to clarify the demographic histories of the domestication process itself, which, together with expanded archaeological studies, can illuminate the origins of crops. Domesticated plant species are found in 160 taxonomic families. Approximately 2500 species have undergone some degree of domestication, and 250 species are considered to be fully domesticated. The evolutionary trajectory from wild to crop species is a complex process. Archaeological records suggest that there was a period of predomestication cultivation while humans first began the deliberate planting of wild stands that had favorable traits. Later, crops likely diversified as they were grown in new areas, sometimes beyond the climatic niche of their wild relatives. However, the speed and level of human intentionality during domestication remains a topic of active discussion. These processes led to the so-called domestication syndrome, that is, a group of traits that can arise through human preferences for ease of harvest and growth advantages under human propagation. These traits included reduced dispersal ability of seeds and fruits, changes to plant structure, and changes to plant defensive characteristics and palatability. Domestication implies the action of selective sweeps on standing genetic variation, as well as new genetic variation introduced via mutation or introgression. Furthermore, genetic bottlenecks during domestication or during founding events as crops moved away from their centers of origin may have further altered gene pools. To date, a few hundred genes and loci have been identified by classical genetic and association mapping as targets of domestication and postdomestication divergence. However, only a few of these have been characterized, and for even fewer is the role of the wild-type allele in natural populations understood. After domestication, only favorable haplotypes are retained around selected genes, which creates a genetic valley with extremely low genetic diversity. These “selective sweeps” can allow mildly deleterious alleles to come to fixation and may create a genetic load in the cultivated gene pool. Although the population-wide genomic consequences of domestication offer several predictions for levels of the genetic diversity in crops, our understanding of how this diversity corresponds to nutritional aspects of crops is not well understood. Many studies have found that modern cultivars have lower levels of key micronutrients and vitamins. We suspect that selection for palatability and increased yield at domestication and during postdomestication divergence exacerbated the low nutrient levels of many crops, although relatively little work has examined this question. Lack of diversity in modern germplasm may further limit our capacity to breed for higher nutrient levels, although little effort has gone into this beyond a handful of staple crops. This is an area where an understanding of domestication across many crop taxa may provide the necessary insight for breeding more nutritious crops in a rapidly changing world.

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Genetic Diversity in the Italian Holstein Dairy Cattle Based on Pedigree and SNP Data Prior and After Genomic Selection

Frontiers in Veterinary Science ◽

10.3389/fvets.2021.773985 ◽

2022 ◽

Vol 8 ◽

Author(s):

Michela Ablondi ◽

Alberto Sabbioni ◽

Giorgia Stocco ◽

Claudio Cipolat-Gotet ◽

Christos Dadousis ◽

...

Keyword(s):

Genetic Diversity ◽

Dairy Cattle ◽

Population Size ◽

Genomic Selection ◽

Effective Population Size ◽

Genomic Data ◽

Future Market ◽

Nucleotide Polymorphisms ◽

Effective Population ◽

Snp Data

Genetic diversity has become an urgent matter not only in small local breeds but also in more specialized ones. While the use of genomic data in livestock breeding programs increased genetic gain, there is increasing evidence that this benefit may be counterbalanced by the potential loss of genetic variability. Thus, in this study, we aimed to investigate the genetic diversity in the Italian Holstein dairy cattle using pedigree and genomic data from cows born between 2002 and 2020. We estimated variation in inbreeding, effective population size, and generation interval and compared those aspects prior to and after the introduction of genomic selection in the breed. The dataset contained 84,443 single-nucleotide polymorphisms (SNPs), and 74,485 cows were analyzed. Pedigree depth based on complete generation equivalent was equal to 10.67. A run of homozygosity (ROH) analysis was adopted to estimate SNP-based inbreeding (FROH). The average pedigree inbreeding was 0.07, while the average FROH was more than double, being equal to 0.17. The pattern of the effective population size based on pedigree and SNP data was similar although different in scale, with a constant decrease within the last five generations. The overall inbreeding rate (ΔF) per year was equal to +0.27% and +0.44% for Fped and FROH throughout the studied period, which corresponded to about +1.35% and +2.2% per generation, respectively. A significant increase in the ΔF was found since the introduction of genomic selection in the breed. This study in the Italian Holstein dairy cattle showed the importance of controlling the loss of genetic diversity to ensure the long-term sustainability of this breed, as well as to guarantee future market demands.

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Heterogeneity in effective size across the genome: effects on the Inverse Instantaneous Coalescence Rate (IICR) and implications for demographic inference under linked selection.

10.1101/2021.06.11.448122 ◽

2021 ◽

Author(s):

Simon Boitard ◽

Armando Arredondo ◽

Camille Noûs ◽

Lounes Chikhi ◽

Olivier Mazet

Keyword(s):

Genetic Diversity ◽

Balancing Selection ◽

Effective Population ◽

Recombination Rates ◽

Genome Wide ◽

Coalescence Rate ◽

Demographic Inference ◽

The Impact ◽

Linked Selection ◽

Coalescence Times

The relative contribution of selection and neutrality in shaping species genetic diversity is one of the most central and controversial questions in evolutionary theory. Genomic data provide growing evidence that linked selection, i.e. the modification of genetic diversity at neutral sites through linkage with selected sites, might be pervasive over the genome. Several studies proposed that linked selection could be modelled as first approximation by a local reduction (e.g. purifying selection, selective sweeps) or increase (e.g. balancing selection) of effective population size (Ne). At the genome-wide scale, this leads to a large variance of Ne from one region to another, reflecting the heterogeneity of selective constraints and recombination rates between regions. We investigate here the consequences of this variation of Ne on the genome-wide distribution of coalescence times. The underlying motivation concerns the impact of linked selection on demographic inference, because the distribution of coalescence times is at the heart of several important demographic inference approaches. Using the concept of Inverse Instantaneous Coalescence Rate, we demonstrate that in a panmictic population, linked selection always results in a spurious apparent decrease of Ne along time. Balancing selection has a particularly large effect, even when it concerns a very small part of the genome. We quantify the expected magnitude of the spurious decrease of Ne in humans and Drosophila melanogaster, based on Ne distributions inferred from real data in these species. We also find that the effect of linked selection can be significantly reduced by that of population structure.

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52 Genomic selection in the beef industry: Current achievements and future directions

Journal of Animal Science ◽

10.1093/jas/skz258.110 ◽

2019 ◽

Vol 97 (Supplement_3) ◽

pp. 54-55

Author(s):

Daniel W Moser ◽

Stephen P Miller ◽

Kelli J Retallick ◽

Duc Lu ◽

Larry A Kuehn

Keyword(s):

Beef Cattle ◽

Genomic Selection ◽

Large Scale ◽

Genetic Evaluation ◽

Fiscal Year ◽

Genomic Testing ◽

Routine Practice ◽

The Past ◽

Angus Cattle ◽

Genetic Evaluations

Abstract In the past decade, genomic testing of beef cattle has evolved from applications in research to a routine practice for many beef cattle seedstock breeders. Testing for lethal genetic conditions or parentage was many breeders’ first experience with genomic testing. While the American Angus Association (AAA) began utilizing 384 SNP genotypes in genetic evaluations in 2009, the adoption of genotyping with higher density (~50,000 SNP) arrays by AAA in 2010 launched large-scale genotyping of Angus cattle for genetic evaluation. AAA transitioned from semi-annual to weekly genetic evaluations in 2010, and cost of genotyping decreased from $139 per animal in 2011, to $37 in 2017. In fiscal year 2018, AAA members genotyped over 160,000 animals for genetic evaluation, and as of April 2019, the AAA and Canadian Angus Association joint genetic evaluation includes over 635,000 genotyped animals. Now genotyping arrays with Angus-specific SNP content are used. The primary benefit to Angus breeders has been increased accuracy of genetic prediction for young animals, especially for traits with limited phenotypic information such as carcass traits, feed intake and mature cow size. Future benefits from genotyping include identification and selection against embryonic lethal alleles, better characterization of inbreeding, and selection tools for additional traits relevant to or measured in unique environments. Electronic sensors and other novel approaches may yield previously unmeasurable phenotypes for health and efficiency traits, which can be extended to wider populations for selection using genomics. New techniques such as DNA pooling and genotyping by sequencing may reduce costs enabling widespread testing in commercial cow-calf and cattle feeding enterprises. The application of genomic selection has clearly been a significant advancement in genetic selection in Angus cattle in the past ten years. This early adoption will expedite subsequent genomic tools at an increasing rate and will foster innovation.

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SNP-based analysis reveals unexpected features of genetic diversity, parental contributions and pollen contamination in a white spruce breeding program

Scientific Reports ◽

10.1038/s41598-021-84566-2 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Esteban Galeano ◽

Jean Bousquet ◽

Barb R. Thomas

Keyword(s):

Genetic Diversity ◽

Population Size ◽

Effective Population Size ◽

White Spruce ◽

Seed Orchard ◽

Pedigree Reconstruction ◽

Effective Population ◽

Pollen Contamination ◽

Contamination Levels ◽

The Impact

AbstractAccurate monitoring of genetic diversity levels of seedlots and mating patterns of parents from seed orchards are crucial to ensure that tree breeding programs are long-lasting and will deliver anticipated genetic gains. We used SNP genotyping to characterize founder trees, five bulk seed orchard seedlots, and trees from progeny trials to assess pollen contamination and the impact of severe roguing on genetic diversity and parental contributions in a first-generation open-pollinated white spruce clonal seed orchard. After severe roguing (eliminating 65% of the seed orchard trees), we found a slight reduction in the Shannon Index and a slightly negative inbreeding coefficient, but a sharp decrease in effective population size (eightfold) concomitant with sharp increase in coancestry (eightfold). Pedigree reconstruction showed unequal parental contributions across years with pollen contamination levels between 12 and 51% (average 27%) among seedlots, and 7–68% (average 30%) among individual genotypes within a seedlot. These contamination levels were not correlated with estimates obtained using pollen flight traps. Levels of pollen contamination also showed a Pearson’s correlation of 0.92 with wind direction, likely from a pollen source 1 km away from the orchard under study. The achievement of 5% genetic gain in height at rotation through eliminating two-thirds of the orchard thus generated a loss in genetic diversity as determined by the reduction in effective population size. The use of genomic profiles revealed the considerable impact of roguing on genetic diversity, and pedigree reconstruction of full-sib families showed the unanticipated impact of pollen contamination from a previously unconsidered source.

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Food Resources Biodiversity: The Case of Local Cattle in Slovakia

Sustainability ◽

10.3390/su13031296 ◽

2021 ◽

Vol 13 (3) ◽

pp. 1296

Author(s):

Radovan Kasarda ◽

Luboš Vostrý ◽

Hana Vostrá-Vydrová ◽

Kristína Candráková ◽

Nina Moravčíková

Keyword(s):

Food Resources ◽

Significant Loss ◽

Phenotypic Traits ◽

Production Traits ◽

Effective Population ◽

Production Type ◽

Genome Wide Data ◽

Differentiation Degree ◽

Genomic Inbreeding ◽

The Impact

This study aimed to assess the level of biodiversity in selected local cattle populations as important food resources in Slovakia. The biodiversity level was derived from the genome-wide data collected for dairy (Jersey), dual-purpose (Slovak Pinzgau, Slovak Spotted), and beef breeds (Charolais, Limousine). The commonly used indices, genomic inbreeding (FROH, FGRM, FHOM, FUNI) and effective population size (NeLD), were used to quantify the impact of relatives mating on the genome of analysed populations. Even if the low NeLD estimates signalise significant loss of genetic variability within populations, the genomic inbreeding under 1% (except Jersey) showed that the intensity of diversity loss is not so rapid and can be managed by the re-arrangement of long-term breeding strategies. The analysis of genetic differentiation degree across populations assumed that the specialisation of breeds during their grading-up led to the specific nucleotide changes, especially in genes responsible for preferred phenotypic traits. The breed-specific differences observed mainly in the genome of Charolais (carcass traits) and Jersey (milk production traits) populations resulted from the polymorphisms in CAPN1 (μ-calpain) and CSN1S2 (casein alpha s2) genes, respectively. Obtained results confirmed that the specific haplotypes are strongly associated with the genetic nature of breed depending on production type.

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Demography, genetic, and extinction process in a spatially structured population of lekking bird

10.1101/705301 ◽

2019 ◽

Author(s):

Hugo Cayuela ◽

Jérôme G. Prunier ◽

Martin Laporte ◽

Jérôme Gippet ◽

Laurent Boualit ◽

...

Keyword(s):

Genetic Diversity ◽

Population Size ◽

Inbreeding Depression ◽

Allee Effect ◽

Genetic Factors ◽

Effective Population ◽

Vosges Mountains ◽

Extinction Process ◽

Structured Population ◽

Spatially Structured Population

AbstractUnderstanding the mechanisms underlying biological extinctions is a critical challenge for conservation biologists. Both deterministic (e.g. habitat loss, fragmentation) and stochastic (i.e. demographic stochasticity, Allee effect) demographic processes are involved in population decline. Simultaneously, a decrease of population size has far-reaching consequences for genetics of populations by increasing the risk of inbreeding and the effects of genetic drift, which together inevitably results in a loss of genetic diversity and a reduced effective population size (Ne). These genetic factors may retroactively affect vital rates (a phenomenon coined ‘inbreeding depression’), and therefore reduce population growth and accelerate the extinction process of small populations. To date, few studies have simultaneously examined the demographic and genetic mechanisms driving the extinction of wild populations, and have most of the time neglected the spatial structure of populations. In this study, we examined demographic and genetic factors involved in the extinction process of a spatially structured population of a lekking bird, the western capercaillie (Tetrao urogallus). To address this issue, we collected capture-recapture and genetic data over a 6-years period in Vosges mountains, France. Our study showed that the population of T. urogallus experienced a severe decline between 2010 and 2015. We did not detect any Allee effect on survival and recruitment. By contrast, individuals of both sexes dispersed to avoid small leks, suggesting a behavioral response to a mate finding Allee effect. In parallel to this demographic decline, the population showed a low genetic diversity and high inbreeding. In addition, the effective population sizes at both lek and population levels was low. Despite this, we did not detected evidence of inbreeding depression: neither survival nor recruitment were affected by individual inbreeding level. Our study underlines the benefit from combining demographic and genetic approaches to investigate processes that are involved in biological extinctions.

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Cultural Innovations Influence Patterns of Genetic Diversity in Northwestern Amazonia

10.1101/347336 ◽

2018 ◽

Author(s):

Leonardo Arias ◽

Roland Schröder ◽

Alexander Hübner ◽

Guillermo Barreto ◽

Mark Stoneking ◽

...

Keyword(s):

Genetic Diversity ◽

Native American ◽

Cultural Practices ◽

Demographic History ◽

Population History ◽

Human Populations ◽

Effective Population ◽

Trade Networks ◽

Males And Females ◽

The Impact

ABSTRACTHuman populations often exhibit contrasting patterns of genetic diversity in the mtDNA and the non-recombining portion of the Y-chromosome (NRY), which reflect sex-specific cultural behaviors and population histories. Here, we sequenced 2.3 Mb of the NRY from 284 individuals representing more than 30 Native-American groups from Northwestern Amazonia (NWA) and compared these data to previously generated mtDNA genomes from the same groups, to investigate the impact of cultural practices on genetic diversity and gain new insights about NWA population history. Relevant cultural practices in NWA include postmarital residential rules and linguistic-exogamy, a marital practice in which men are required to marry women speaking a different language.We identified 2,969 SNPs in the NRY sequences; only 925 SNPs were previously described. The NRY and mtDNA data showed that males and females experienced different demographic histories: the female effective population size has been larger than that of males through time, and both markers show an increase in lineage diversification beginning ~5,000 years ago, with a male-specific expansion occurring ~3,500 years ago. These dates are too recent to be associated with agriculture, therefore we propose that they reflect technological innovations and the expansion of regional trade networks documented in the archaeological evidence. Furthermore, our study provides evidence of the impact of postmarital residence rules and linguistic exogamy on genetic diversity patterns. Finally, we highlight the importance of analyzing high-resolution mtDNA and NRY sequences to reconstruct demographic history, since this can differ considerably between males and females.

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