Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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    Correction to: Genome-wide SNP data unveils the globalization of domesticated pigs
    Yang, Bin ; Cui, Leilei ; Perez-Enciso, Miguel ; Traspov, Aleksei ; Crooijmans, Richard P.M.A. ; Zinovieva, Natalia ; Schook, Lawrence B. ; Archibald, Alan ; Gatphayak, Kesinee ; Knorr, Christophe ; Triantafyllidis, Alex ; Alexandri, Panoraia ; Semiadi, Gono ; Hanotte, Olivier ; Dias, Deodália ; Dovč, Peter ; Uimari, Pekka ; Iacolina, Laura ; Scandura, Massimo ; Groenen, Martien A.M. ; Huang, Lusheng ; Megens, Hendrik Jan - \ 2020
    Genetics, Selection, Evolution 52 (2020)1. - ISSN 0999-193X - 1 p.

    An amendment to this paper has been published and can be accessed via the original article.

    Ancient pigs reveal a near-complete genomic turnover following their introduction to Europe
    Frantz, Laurent A.F. ; Haile, James ; Lin, Audrey T. ; Scheu, Amelie ; Geörg, Christina ; Benecke, Norbert ; Alexander, Michelle ; Linderholm, Anna ; Mullin, Victoria E. ; Daly, Kevin G. ; Battista, Vincent M. ; Price, Max ; Gron, Kurt J. ; Alexandri, Panoraia ; Arbogast, Rose Marie ; Arbuckle, Benjamin ; Bǎlǎşescu, Adrian ; Barnett, Ross ; Bartosiewicz, László ; Baryshnikov, Gennady ; Bonsall, Clive ; Borić, Dušan ; Boroneanţ, Adina ; Bulatović, Jelena ; Çakirlar, Canan ; Carretero, José Miguel ; Chapman, John ; Church, Mike ; Crooijmans, Richard ; Cupere, Bea De; Detry, Cleia ; Dimitrijevic, Vesna ; Dumitraşcu, Valentin ; Plessis, Louis Du; Edwards, Ceiridwen J. ; Erek, Cevdet Merih ; Erim-Özdoǧan, Asli ; Ervynck, Anton ; Fulgione, Domenico ; Gligor, Mihai ; Götherström, Anders ; Gourichon, Lionel ; Groenen, Martien A.M. ; Helmer, Daniel ; Hongo, Hitomi ; Horwitz, Liora K. ; Irving-Pease, Evan K. ; Lebrasseur, Ophélie ; Lesur, Joséphine ; Malone, Caroline ; Manaseryan, Ninna ; Marciniak, Arkadiusz ; Martlew, Holley ; Mashkour, Marjan ; Matthews, Roger ; Matuzeviciute, Giedre Motuzaite ; Maziar, Sepideh ; Meijaard, Erik ; McGovern, Tom ; Megens, Hendrik Jan ; Miller, Rebecca ; Mohaseb, Azadeh Fatemeh ; Orschiedt, Jörg ; Orton, David ; Papathanasiou, Anastasia ; Pearson, Mike Parker ; Pinhasi, Ron ; Radmanović, Darko ; Ricaut, François Xavier ; Richards, Mike ; Sabin, Richard ; Sarti, Lucia ; Schier, Wolfram ; Sheikhi, Shiva ; Stephan, Elisabeth ; Stewart, John R. ; Stoddart, Simon ; Tagliacozzo, Antonio ; Tasić, Nenad ; Trantalidou, Katerina ; Tresset, Anne ; Valdiosera, Cristina ; Hurk, Youri Van Den; Poucke, Sophie Van; Vigne, Jean Denis ; Yanevich, Alexander ; Zeeb-Lanz, Andrea ; Triantafyllidis, Alexandros ; Gilbert, M.T.P. ; Schibler, Jörg ; Rowley-Conwy, Peter ; Zeder, Melinda ; Peters, Joris ; Cucchi, Thomas ; Bradley, Daniel G. ; Dobney, Keith ; Burger, Joachim ; Evin, Allowen ; Girdland-Flink, Linus ; Larson, Greger - \ 2019
    Proceedings of the National Academy of Sciences of the United States of America 116 (2019)35. - ISSN 0027-8424 - p. 17231 - 17238.
    Domestication - Evolution - Gene flow - Neolithic

    Archaeological evidence indicates that pig domestication had begun by ∼10,500 y before the present (BP) in the Near East, and mitochondrial DNA (mtDNA) suggests that pigs arrived in Europe alongside farmers ∼8,500 y BP. A few thousand years after the introduction of Near Eastern pigs into Europe, however, their characteristic mtDNA signature disappeared and was replaced by haplotypes associated with European wild boars. This turnover could be accounted for by substantial gene flow from local European wild boars, although it is also possible that European wild boars were domesticated independently without any genetic contribution from the Near East. To test these hypotheses, we obtained mtDNA sequences from 2,099 modern and ancient pig samples and 63 nuclear ancient genomes from Near Eastern and European pigs. Our analyses revealed that European domestic pigs dating from 7,100 to 6,000 y BP possessed both Near Eastern and European nuclear ancestry, while later pigs possessed no more than 4% Near Eastern ancestry, indicating that gene flow from European wild boars resulted in a near-complete disappearance of Near East ancestry. In addition, we demonstrate that a variant at a locus encoding black coat color likely originated in the Near East and persisted in European pigs. Altogether, our results indicate that while pigs were not independently domesticated in Europe, the vast majority of human-mediated selection over the past 5,000 y focused on the genomic fraction derived from the European wild boars, and not on the fraction that was selected by early Neolithic farmers over the first 2,500 y of the domestication process.

    Water-Food-Energy Nexus under Climate Change in Sardinia
    Trabucco, Antonio ; Sušnik, Janez ; Vamvakeridou-Lyroudia, Lydia ; Evans, Barry ; Masia, Sara ; Blanco, Maria ; Roson, Roberto ; Sartori, Martina ; Alexandri, Eva ; Brouwer, Floor ; Spano, Donatella ; Damiano, Alfonso ; Virdis, Andrea ; Sistu, Giovanni ; Pulino, Daniele ; Statzu, Vania ; Madau, Fabio ; Strazzera, Elisabetta ; Mereu, Simone - \ 2018
    BMC Proceedings 2 (2018)11. - ISSN 1753-6561
    Land, food, energy, water and climate are linked and interconnected into a Nexus, characterized by complexity and feedbacks. An integrated management of the Nexus is critical to understand conflicts/synergies and secure efficient and sustainable use of resources, especially under climate change. The Nexus perspective is applied to Sardinia, as regional case study, to better understand and improve integrated resource management and relevant policy initiatives. Vulnerability of Sardinia Nexus is assessed under several climate projections by articulated balances of resources (water, energy) availability and sustainable development goals, at regional and sub-regional scales, accounting for demands and conflicts among key economic sectors (agriculture, hydro-power, tourism).
    The Nexus Concept Integrating Energy and Resource Efficiency for Policy Assessments : A Comparative Approach from Three Cases
    Brouwer, Floor ; Vamvakeridou-Lyroudia, Lydia ; Alexandri, Eva ; Bremere, Ingrida ; Griffey, Matthew ; Linderhof, Vincent - \ 2018
    Sustainability 10 (2018)12. - ISSN 2071-1050
    As the world increasingly runs up against physical constraints of energy, land, water, and food, there is a growing role for policy to reduce environmental pressures without adversely affecting increases in prosperity. There is therefore a need for policy makers to understand the potential trade-offs and/or synergies between the uses of these different resources, i.e., to encompass the water–energy–food–land nexus for policy and decision making, where it is no longer possible to ignore the limitations in land availability and its links to other natural resources. This paper proposes a modelling approach to help to assess various policies from a nexus perspective. The global macro-econometric model (E3ME) explores a low-carbon transition through different sets of energy and climate policies applied at different spatial scales. The limitations of the E3ME model in assessing nexus interactions are discussed. The paper also argues and offers an explanation for why no single traditional or classic model has the potential to cover all parts of the nexus in a satisfactory way, including feedback loops and interactions between nexus components. Other approaches and methodologies suitable for complexity science modelling (e.g., system dynamics modelling) are proposed, providing a possible means to capture the holistic approach of the nexus in policy-making by including causal and feedback loops to the model components. Based on three case studies in Europe, the paper clarifies the different steps (from policy design towards conceptual model) in modelling the nexus linkages and interactions at the national and regional levels. One case study (The Netherlands) considers national low-carbon transitions at national level. Two other case studies (Latvia and southwest UK) focus on how renewable energy may impact the nexus. A framework is proposed for the generic application of quantitative modelling approaches to assess nexus linkages. The value of the nexus concept for the efficient use of resources is demonstrated, and recommendations for policies supporting the nexus are presented.
    Data from: Genome-wide SNP data unveils the globalization of domesticated pigs
    Yang, Bin ; Cui, Leilei ; Pérez-Enciso, M. ; Traspov, Aleksei ; Crooijmans, R.P.M.A. ; Zinovieva, Natalia ; Schook, Lawrence B. ; Gatphayak, Kesinee ; Knorr, Christophe ; Triantafyllidis, Alex ; Alexandri, Panoraia ; Semiadi, Gono ; Hanotte, Olivier ; Dias, Deodália ; Dovč, Peter ; Uimari, Pekka ; Iacolina, Laura ; Scandura, Massimo ; Groenen, M. ; Huang, L. ; Megens, H.J.W.C. - \ 2017
    National Key Laboratory for Pig Genetic Improvement and Production Technology
    pig - domestication - genome - selection
    Background: Pigs were domesticated independently in Eastern and Western Eurasia early during the agricultural revolution, and have since been transported and traded across the globe. Here, we present a worldwide survey on 60K genome-wide single nucleotide polymorphism (SNP) data for 2093 pigs, including 1839 domestic pigs representing 122 local and commercial breeds, 215 wild boars, and 39 out-group suids, from Asia, Europe, America, Oceania and Africa. The aim of this study was to infer global patterns in pig domestication and diversity related to demography, migration, and selection. Results: A deep phylogeographic division reflects the dichotomy between early domestication centers. In the core Eastern and Western domestication regions, Chinese pigs show differentiation between breeds due to geographic isolation, whereas this is less pronounced in European pigs. The inferred European origin of pigs in the Americas, Africa, and Australia reflects European expansion during the sixteenth to nineteenth centuries. Human-mediated introgression, which is due, in particular, to importing Chinese pigs into the UK during the eighteenth and nineteenth centuries, played an important role in the formation of modern pig breeds. Inbreeding levels vary markedly between populations, from almost no runs of homozygosity (ROH) in a number of Asian wild boar populations, to up to 20% of the genome covered by ROH in a number of Southern European breeds. Commercial populations show moderate ROH statistics. For domesticated pigs and wild boars in Asia and Europe, we identified highly differentiated loci that include candidate genes related to muscle and body development, central nervous system, reproduction, and energy balance, which are putatively under artificial selection. Conclusions: Key events related to domestication, dispersal, and mixing of pigs from different regions are reflected in the 60K SNP data, including the globalization that has recently become full circle since Chinese pig breeders in the past decades started selecting Western breeds to improve local Chinese pigs. Furthermore, signatures of ongoing and past selection, acting at different times and on different genetic backgrounds, enhance our insight in the mechanism of domestication and selection. The global diversity statistics presented here highlight concerns for maintaining agrodiversity, but also provide a necessary framework for directing genetic conservation.
    Genome-wide SNP data unveils the globalization of domesticated pigs
    Yang, Bin ; Cui, Leilei ; Pérez-Enciso, M. ; Traspov, Aleksei ; Crooijmans, Richard P.M.A. ; Zinovieva, Natalia ; Schook, Lawrence B. ; Archibald, Alan ; Gatphayak, Kesinee ; Knorr, Christophe ; Triantafyllidis, Alex ; Alexandri, Panoraia ; Semiadi, Gono ; Hanotte, Olivier ; Dias, Deodália ; Dovč, Peter ; Uimari, Pekka ; Iacolina, Laura ; Scandura, Massimo ; Groenen, Martien A.M. ; Huang, L. ; Megens, Hendrik Jan - \ 2017
    Genetics, Selection, Evolution 49 (2017). - ISSN 0999-193X - 15 p.

    Background: Pigs were domesticated independently in Eastern and Western Eurasia early during the agricultural revolution, and have since been transported and traded across the globe. Here, we present a worldwide survey on 60K genome-wide single nucleotide polymorphism (SNP) data for 2093 pigs, including 1839 domestic pigs representing 122 local and commercial breeds, 215 wild boars, and 39 out-group suids, from Asia, Europe, America, Oceania and Africa. The aim of this study was to infer global patterns in pig domestication and diversity related to demography, migration, and selection. Results: A deep phylogeographic division reflects the dichotomy between early domestication centers. In the core Eastern and Western domestication regions, Chinese pigs show differentiation between breeds due to geographic isolation, whereas this is less pronounced in European pigs. The inferred European origin of pigs in the Americas, Africa, and Australia reflects European expansion during the sixteenth to nineteenth centuries. Human-mediated introgression, which is due, in particular, to importing Chinese pigs into the UK during the eighteenth and nineteenth centuries, played an important role in the formation of modern pig breeds. Inbreeding levels vary markedly between populations, from almost no runs of homozygosity (ROH) in a number of Asian wild boar populations, to up to 20% of the genome covered by ROH in a number of Southern European breeds. Commercial populations show moderate ROH statistics. For domesticated pigs and wild boars in Asia and Europe, we identified highly differentiated loci that include candidate genes related to muscle and body development, central nervous system, reproduction, and energy balance, which are putatively under artificial selection. Conclusions: Key events related to domestication, dispersal, and mixing of pigs from different regions are reflected in the 60K SNP data, including the globalization that has recently become full circle since Chinese pig breeders in the past decades started selecting Western breeds to improve local Chinese pigs. Furthermore, signatures of ongoing and past selection, acting at different times and on different genetic backgrounds, enhance our insight in the mechanism of domestication and selection. The global diversity statistics presented here highlight concerns for maintaining agrodiversity, but also provide a necessary framework for directing genetic conservation.

    Data from: Distinguishing migration events of different timing for wild boar in the Balkans
    Alexandri, Panoraia ; Megens, H.J.W.C. ; Crooijmans, R.P.M.A. ; Groenen, M. ; Goedbloed, D.J. ; Herrero Medrano, J.M. ; Rund, L.A. ; Schook, Lawrence B. ; Chatzinikos, Evangelos ; Triantaphyllidis, Costas ; Triantafyllidis, Alexander - \ 2016
    Wageningen University & Research
    SNPs - population genetics - recent migration - genetic diversity - mammal - microsatellites - Sus scrofa
    Aim: We compared the power of different nuclear markers to investigate genetic structure of southern Balkan wild boar. We distinguished between historic events, such as isolation in different refugia during glacial periods, from recent demographic processes, such as naturally occurring expansions. Location: Southern Balkans/Greece. Methods: We sampled 555 wild boars from 20 different locations in southern Balkans/Greece. All individuals were analysed with 10 microsatellites and a subgroup of 91 with 49,508 single nucleotide polymorphisms (SNPs). Patterns of genetic structure and demographic processes were assessed with Bayesian clustering, linkage disequilibrium and past effective population size estimation analysis. Results: Both microsatellite and SNP data analyses detected genetic structure caused by historic events and support the existence of three groups in the studied area. A hybrid zone between two of the groups was also detected. We also showed that genome-wide SNP data analysis can identify recent events in bottlenecked populations. Main conclusions: We inferred the three groups diverged ~50,000–10,000 yr bp when populations contracted to different refugia. Our findings strengthened the evidence that the southern Balkan area was a glacial refugium including further local smaller refugia. Genome-wide genotyping inferred a recent population expansion that can mimic a ‘refugium within refugium’ scenario. It seems that microsatellite data tend to overestimate genetic structure when genetic drift happens in bottlenecked populations over a short distance. Therefore, genome-wide SNPs are more powerful at inferring phylogeography in natural populations, resolving inconsistencies from mitochondrial and microsatellite data sets.
    Distinguishing migration events of different timing for wild boar in the Balkans
    Alexandri, Panoraia ; Megens, H.J.W.C. ; Crooijmans, R.P.M.A. ; Groenen, M. ; Goedbloed, D.J. ; Herrero Medrano, J.M. ; Rund, L.A. ; Schook, Lawrence B. ; Chatzinikos, Evangelos ; Triantaphyllidis, Costas ; Triantafyllidis, Alexander - \ 2016
    Journal of Biogeography 44 (2016)2. - ISSN 0305-0270 - p. 259 - 270.
    Aim
    We compared the power of different nuclear markers to investigate genetic structure of southern Balkan wild boar. We distinguished between historic events, such as isolation in different refugia during glacial periods, from recent demographic processes, such as naturally occurring expansions.
    Location Southern Balkans/Greece.
    Methods
    We sampled 555 wild boars from 20 different locations in southern Balkans/Greece. All individuals were analysed with 10 microsatellites and a subgroup of 91 with 49,508 single nucleotide polymorphisms (SNPs). Patterns of
    genetic structure and demographic processes were assessed with Bayesian clustering, linkage disequilibrium and past effective population size estimation
    analysis.
    Results
    Both microsatellite and SNP data analyses detected genetic structure caused by historic events and support the existence of three groups in the studied area. A hybrid zone between two of the groups was also detected. We also showed that genome-wide SNP data analysis can identify recent events in bottlenecked
    populations.
    Main conclusions
    We inferred the three groups diverged ~50,000–10,000 yr bp when populations contracted to different refugia. Our findings strengthened the evidence that the southern Balkan area was a glacial refugium including further local smaller refugia. Genome-wide genotyping inferred a recent population expansion that can mimic a ‘refugium within refugium’ scenario. It seems that microsatellite data tend to overestimate genetic structure when genetic drift happens in bottlenecked populations over a short distance. Therefore, genome-wide SNPs are more powerful at inferring phylogeography in natural populations, resolving inconsistencies from mitochondrial and microsatellite data sets.
    Genomic diversity and differentiation of a managed island wild boar population
    Iacolina, L. ; Scandura, M. ; Goedbloed, D.J. ; Alexandri, P. ; Crooijmans, R.P.M.A. ; Larson, G. ; Archibald, A. ; Apollonio, M. ; Schook, L.B. ; Groenen, M.A.M. ; Megens, H.J. - \ 2016
    Heredity 116 (2016)1. - ISSN 0018-067X - p. 60 - 67.

    The evolution of island populations in natural systems is driven by local adaptation and genetic drift. However, evolutionary pathways may be altered by humans in several ways. The wild boar (WB) (Sus scrofa) is an iconic game species occurring in several islands, where it has been strongly managed since prehistoric times. We examined genomic diversity at 49 803 single-nucleotide polymorphisms in 99 Sardinian WBs and compared them with 196 wild specimens from mainland Europe and 105 domestic pigs (DP; 11 breeds). High levels of genetic variation were observed in Sardinia (80.9% of the total number of polymorphisms), which can be only in part associated to recent genetic introgression. Both Principal Component Analysis and Bayesian clustering approach revealed that the Sardinian WB population is highly differentiated from the other European populations (F ST =0.126-0.138), and from DP (F ST =0.169). Such evidences were mostly unaffected by an uneven sample size, although clustering results in reference populations changed when the number of individuals was standardized. Runs of homozygosity (ROHs) pattern and distribution in Sardinian WB are consistent with a past expansion following a bottleneck (small ROHs) and recent population substructuring (highly homozygous individuals). The observed effect of a non-random selection of Sardinian individuals on diversity, F ST and ROH estimates, stressed the importance of sampling design in the study of structured or introgressed populations. Our results support the heterogeneity and distinctiveness of the Sardinian population and prompt further investigations on its origins and conservation status.

    Data from: Genomic diversity and differentiation of a managed island wild boar population
    Iacolina, L. ; Scandura, M. ; Goedbloed, D.J. ; Alexandri, Panoraia ; Crooijmans, R.P.M.A. ; Larson, G. ; Archibald, A.L. ; Apollonio, M. ; Schook, L.B. ; Groenen, M. ; Megens, H.J.W.C. - \ 2015
    Wageningen University & Research
    genetic diversity - Hybridization - Population Genetics - SNPs
    Structure input file. The four populations correspond to the "Group" column in the file Individuals_info.txt
    Estimation of genetic parameters and breeding values across challenged environments to select for robust pigs
    Herrero-Medrano, J.M. ; Mathur, P.K. ; Napel, Ten J. ; Rashidi, H. ; Alexandri, P. ; Knol, E.F. ; Mulder, H.A. - \ 2015
    Journal of Animal Science 93 (2015)4. - ISSN 0021-8812 - p. 1494 - 1502.
    Robustness is an important issue in the pig production industry. Since pigs from international breeding organizations have to withstand a variety of environmental challenges, selection of pigs with the inherent ability to sustain their productivity in diverse environments may be an economically feasible approach in the livestock industry. The objective of this study was to estimate genetic parameters and breeding values across different levels of environmental challenge load. The challenge load (CL) was estimated as the reduction in reproductive performance during different weeks of a year using 925,711 farrowing records from farms distributed worldwide. A wide range of levels of challenge, from favorable to unfavorable environments, was observed among farms with high CL values being associated with confirmed situations of unfavorable environment. Genetic parameters and breeding values were estimated in high- and low-challenge environments using a bivariate analysis, as well as across increasing levels of challenge with a random regression model using Legendre polynomials. Although heritability estimates of number of pigs born alive were slightly higher in environments with extreme CL than in those with intermediate levels of CL, the heritabilities of number of piglet losses increased progressively as CL increased. Genetic correlations among environments with different levels of CL suggest that selection in environments with extremes of low or high CL would result in low response to selection. Therefore, selection programs of breeding organizations that are commonly conducted under favorable environments could have low response to selection in commercial farms that have unfavorable environmental conditions. Sows that had experienced high levels of challenge at least once during their productive life were ranked according to their EBV. The selection of pigs using EBV ignoring environmental challenges or on the basis of records from only favorable environments resulted in a sharp decline in productivity as the level of challenge increased. In contrast, selection using the random regression approach resulted in limited change in productivity with increasing levels of challenge. Hence, we demonstrate that the use of a quantitative measure of environmental CL and a random regression approach can be comprehensively combined for genetic selection of pigs with enhanced ability to maintain high productivity in harsh environments.
    TRES: Identification of Discriminatory and Informative SNPs from Population Genomic Data
    Kavakiotis, I. ; Triantafyllidis, A. ; Ntelidou, D. ; Alexandri, P. ; Megens, H.J.W.C. ; Crooijmans, R.P.M.A. ; Groenen, M.A.M. ; Tsoumakas, G. ; Vlahavas, I. - \ 2015
    Journal of Heredity 106 (2015)5. - ISSN 0022-1503 - p. 672 - 676.
    The advent of high-throughput genomic technologies is enabling analyses on thousands or even millions of single-nucleotide polymorphisms (SNPs). At the same time, the selection of a minimum number of SNPs with the maximum information content is becoming increasingly problematic. Available locus ranking programs have been accused of providing upwardly biased results (concerning the predicted accuracy of the chosen set of markers for population assignment), cannot handle high-dimensional datasets, and some of them are computationally intensive. The toolbox for ranking and evaluation of SNPs (TRES) is a collection of algorithms built in a user-friendly and computationally efficient software that can manipulate and analyze datasets even in the order of millions of genotypes in a matter of seconds. It offers a variety of established methods for evaluating and ranking SNPs on user defined groups of populations and produces a set of predefined number of top ranked loci. Moreover, dataset manipulation algorithms enable users to convert datasets in different file formats, split the initial datasets into train and test sets, and finally create datasets containing only selected SNPs occurring from the SNP selection analysis for later on evaluation in dedicated software such as GENECLASS. This application can aid biologists to select loci with maximum power for optimization of cost-effective panels with applications related to e.g. species identification, wildlife management, and forensic problems.
    Genetic evaluation for disease resistance and tolerance in pigs using reproduction records
    Mathur, P.K. ; Herrero-Medrano, J. ; Alexandri, P. ; Knol, E.F. ; Rashidi, H. ; Mulder, H.A. ; Napel, J. ten - \ 2014
    Estimating challenge load due to disease outbreaks and other challenges using reproduction records of sows
    Mathur, P.K. ; Herrero-Medrano, J. ; Alexandri, P. ; Knol, E.F. ; Napel, J. ten; Rashidi, H. ; Mulder, H.A. - \ 2014
    Journal of Animal Science 92 (2014)12. - ISSN 0021-8812 - p. 5374 - 5381.
    environment interaction - breeding programs - respiratory syndrome - genotype - pigs - cattle - models
    A method was developed and tested to estimate challenge load due to disease outbreaks and other challenges in sows using reproduction records. The method was based on reproduction records from a farm with known disease outbreaks. It was assumed that the reduction in weekly reproductive output within a farm is proportional to the magnitude of the challenge. As the challenge increases beyond certain threshold, it is manifested as an outbreak. The reproduction records were divided into 3 datasets. The first dataset called the Training dataset consisted of 57,135 reproduction records from 10,901 sows from 1 farm in Canada with several outbreaks of porcine reproductive and respiratory syndrome (PRRS). The known disease status of sows was regressed on the traits number born alive, number of losses as a combination of still birth and mummified piglets, and number of weaned piglets. The regression coefficients from this analysis were then used as weighting factors for derivation of an index measure called challenge load indicator. These weighting factors were derived with i) a two-step approach using residuals or year-week solutions estimated from a previous step, and ii) a single-step approach using the trait values directly. Two types of models were used for each approach: a logistic regression model and a general additive model. The estimates of challenge load indicator were then compared based on their ability to detect PRRS outbreaks in a Test dataset consisting of records from 65,826 sows from 15 farms in the Netherlands. These farms differed from the Canadian farm with respect to PRRS virus strains, severity and frequency of outbreaks. The single-step approach using a general additive model was best and detected 14 out of the 15 outbreaks. This approach was then further validated using the third dataset consisting of reproduction records of 831,855 sows in 431 farms located in different countries in Europe and America. A total of 41 out of 48 outbreaks detected using data analysis were confirmed based on diagnostic information received from the farms. Among these, 30 outbreaks were due to PRRS while 11 were due to other diseases and challenging conditions. The results suggest that proposed method could be useful for estimation of challenge load and detection of challenge phases such as disease outbreaks.
    Effects of Isolation and human-mediated introgression in shaping the genomic distinctiveness of an insular large mammal
    Iacolina, L. ; Scandura, M. ; Goedbloed, D.J. ; Alexandri, P. ; Crooijmans, R.P.M.A. ; Larson, G. ; Groenen, M. ; Megens, H.J.W.C. - \ 2014
    The evolution of island populations in natural systems is driven by local adaptation and genetic drift. However humans can affect evolutionary pathways in several ways, especially in managed species. The wild boar (Sus scrofa) is an iconic game species and is highly managed throughout its distribution range, including islands where it was introduced in prehistoric times. We examined the current genomic diversity of the Sardinian wild boar population analysing the variation at 49,803 SNPs in 99 wild boars collected throughout the island and comparing them with 196 mainland wild specimens and 105 domestic pigs belonging to 11 breeds. The analysis of SNP data by Bayesian clustering approaches and Allele Frequency Spectrum Assessment revealed that the Sardinian wild boar population is highly differentiated from the other European populations (FST = 0.126 - 0.138), and from domestic pigs, including local free-ranging stocks (FST = 0.169). Signatures of introgression were investigated by different methods and detected in 6% of the Sardinian sample. The removal of these introgressed individuals changed only slightly the distinctiveness of the Sardinian population and its overall levels of genomic variation, part of which showed possible signs of local adaptation. The patterns of diversity emerging from our analyses suggest a long history of isolation and demographic stability of the population, followed by more recent admixture. This study confirms the usefulness of genome-wide genotyping in recognizing native versus exotic sources of genetic variation in wild populations and opens new perspectives towards the understanding of microevolutionary processes in managed species
    Genome-wide SNP analysis reveals recent genetic introgression from domestic pigs into Northwest European wild boar populations
    Goedbloed, D.J. ; Megens, H.J.W.C. ; Hooft, W.F. van; Herrero-Medrano, J. ; Lutz, W. ; Alexandri, P. ; Crooijmans, R.P.M.A. ; Groenen, M.A.M. ; Wieren, S.E. van; Ydenberg, R.C. ; Prins, H.H.T. - \ 2013
    Molecular Ecology 22 (2013)3. - ISSN 0962-1083 - p. 856 - 866.
    sus-scrofa - snp discovery - dna - association - diversity - program - ecology - density - markers - set
    Present-day genetic introgression from domestic pigs into European wild boar has been suggested in various studies. However, no hybrids have been identified beyond doubt mainly because available methods were unable to quantify the extent of introgression and rule out natural processes. Genetic introgression from domestic pigs may have far-reaching ecological consequences by altering traits like the reproduction rate or immunology of wild boar. In this study, we demonstrate a novel approach to investigate genetic introgression in a Northwest (NW) European wild boar data set using a genome-wide single nucleotide polymorphism (SNP) assay developed for domestic pigs. We quantified the extent of introgression using allele frequency spectrum analysis, in silico hybridization simulations and genome distribution patterns of introgressed SNPs. Levels of recent introgression in the study area were expected to be low, as pig farming practices are prevailingly intensive and indoors. However, evidence was found for geographically widespread presence of domestic pig SNPs in 10% of analysed wild boar. This was supported by the identification of two different pig mitochondrial DNA haplotypes in three of the identified hybrid wild boar, suggesting that introgression had occurred from multiple sources (pig breeds). In silico hybridization simulations showed that the level of introgression in the identified hybrid wild boar is equivalent to first-generation hybrids until fifth-generation backcrosses with wild boar. The distribution pattern of introgressed SNPs supported these assignments in four of nine hybrids. The other five hybrids are considered advanced-generation hybrids, resulting from interbreeding among hybrid individuals. Three of nine hybrids were genetically associated with a different wild boar population than the one in which they were sampled. This discrepancy suggests that genetic introgression has occurred through the escape or release of an already hybridized farmed wild boar stock. We conclude that genetic introgression from domestic pigs into NW European wild boar populations is more recent and more common than expected and that genome-wide SNP analysis is a promising tool to quantify recent hybridization in free-living populations.
    Data from: Genome-wide single nucleotide polymorphism analysis reveals recent genetic introgression from domestic pigs into Northwest European wild boar populations
    Goedbloed, D.J. ; Megens, H.J.W.C. ; Hooft, W.F. van; Herrero-Medrano, J. ; Lutz, W. ; Alexandri, P. ; Crooijmans, R.P.M.A. ; Groenen, M. ; Wieren, S.E. van; Ydenberg, R.C. ; Prins, H.H.T. - \ 2012
    Wageningen UR
    hybridisation - mammals - population genetics - empirical - SNP - Sus scrofa
    Present-day genetic introgression from domestic pigs into European wild boar has been suggested in various studies. However, no hybrids have been identified beyond doubt mainly because available methods were unable to quantify the extent of introgression and rule out natural processes. Genetic introgression from domestic pigs may have far-reaching ecological consequences by altering traits like the reproduction rate or immunology of wild boar. In this study, we demonstrate a novel approach to investigate genetic introgression in a Northwest (NW) European wild boar data set using a genome-wide single nucleotide polymorphism (SNP) assay developed for domestic pigs. We quantified the extent of introgression using allele frequency spectrum analysis, in silico hybridization simulations and genome distribution patterns of introgressed SNPs. Levels of recent introgression in the study area were expected to be low, as pig farming practices are prevailingly intensive and indoors. However, evidence was found for geographically widespread presence of domestic pig SNPs in 10% of analysed wild boar. This was supported by the identification of two different pig mitochondrial DNA haplotypes in three of the identified hybrid wild boar, suggesting that introgression had occurred from multiple sources (pig breeds). In silico hybridization simulations showed that the level of introgression in the identified hybrid wild boar is equivalent to first-generation hybrids until fifth-generation backcrosses with wild boar. The distribution pattern of introgressed SNPs supported these assignments in four of nine hybrids. The other five hybrids are considered advanced-generation hybrids, resulting from interbreeding among hybrid individuals. Three of nine hybrids were genetically associated with a different wild boar population than the one in which they were sampled. This discrepancy suggests that genetic introgression has occurred through the escape or release of an already hybridized farmed wild boar stock. We conclude that genetic introgression from domestic pigs into NW European wild boar populations is more recent and more common than expected and that genome-wide SNP analysis is a promising tool to quantify recent hybridization in free-living populations.
    Composition of woody species in a dynamic forest-woodland-savannah mosaic in Uganda: implications for conservation and management
    Nangendo, G. ; Steege, H. ter; Bongers, F.J.J.M. - \ 2006
    Biodiversity and Conservation 15 (2006)4. - ISSN 0960-3115 - p. 1467 - 1495.
    intermediate disturbance hypothesis - falls national-park - tropical forests - rain-forest - vegetation dynamics - ivory-coast - fire - diversity - tree - patterns
    Forest¿woodland¿savannah mosaics are a common feature in the East African landscape. For the conservation of the woody species that occur in such landscapes, the species patterns and the factors that maintain it need to be understood. We studied the woody species distribution in a forest¿woodland¿savannah mosaic in Budongo Forest Reserve, Uganda. The existing vegetation gradients were analyzed using data from a total of 591 plots of 400 or 500 m2 each. Remotely sensed data was used to explore current vegetation cover and the gradients there in for the whole area. A clear species gradient exists in the study area ranging from forest, where there is least disturbance, to wooded grassland, where frequent fire disturbance occurs. Most species are not limited to a specific part of the gradient although many show a maximum abundance at some point along the gradient. Fire and accessibility to the protected area were closely related to variation in species composition along the ordination axis with species like Cynometra alexandri and Uvariopsis congensis occurring at one end of the gradient and Combretum guenzi and Lonchocarpus laxiflorus at the other. The vegetation cover classes identified in the area differed in diversity, density and, especially, basal area. All vegetation cover classes, except open woodland, had indicator species. Diospyros abyssinica, Uvariopsis congensis, Holoptelea grandis and all Celtis species were the indicator species for the forest class, Terminalia velutina and Albizia grandbracteata for closed woodland, Grewia mollis and Combretum mole for very open woodland and Lonchocarpus laxiflorus, Grewia bicolor and Combretum guenzi for the wooded grassland class. Eleven of the species occurred in all cover classes and most of the species that occurred in more than one vegetation cover class showed peak abundance in a specific cover class. Species composition in the study area changes gradually from forest to savannah. Along the gradient, the cover classes are distinguishable in terms of species composition and vegetation structure. These classes are, however, interrelated in species composition. For conservation of the full range of the species within this East African landscape, the mosaic has to be managed as an integrated whole. Burning should be varied over the area with the forest not being burnt at all and the wooded grassland burnt regularly. The different vegetation types that occur between these two extremes should be maintained using a varied fire regime
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