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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Populatieanalyse Groninger Paard
Hoving, A.H. ; Vernooij, Kelly ; berg, Rozemarijn van den; Windig, Jack - \ 2015
Zeldzaam huisdier 40 (2015)4. - ISSN 0929-905X - p. 18 - 19.
paardenrassen - nederland - fokdoelen - groninger paard - populaties - genetica - inteelt - verwantschap - genenbanken - horse breeds - netherlands - breeding aims - groningen horse - populations - genetics - inbreeding - kinship - gene banks
We prijzen Nederlandse paardenrassen zoals het Groninger paard niet alleen omdat ze onderdeel van ons cultuurhistorisch erfgoed zijn maar ook vanwege hun veelzijdigheid en betrouwbare karakter. Helaas is de populatie klein. Dan is een goed doordacht fokbeleid nodig voor het behoud van genetische diversiteit en een gezonde populatie
Beelden van de Das in Nederland in Nederland 1900-2013: van ongedierte tot troeteldier?
Runhaar, Hens ; Runhaar, M. ; Vink, J. - \ 2015
De Levende Natuur 116 (2015)5. - ISSN 0024-1520 - p. 228 - 231.
meles meles - populations - wildlife conservation - wildlife management - attitudes - social change - human-animal relationships - populaties - wildbescherming - wildbeheer - sociale verandering - mens-dier relaties
Het herstel van de Nederlandse dassenpopulatie sinds 1980 is voor een belangrijk deel te verklaren uit een betere bescherming door o.a. de overheid, maar ook uit een andere omgang met de Das door boeren, jagers en bestuurders. Doel van dit artikel is om de beelden van de Das in de loop van de tijd te analyseren om daardoor inzicht te krijgen in de maatschappelijke kant van het herstel van de dassenpopulatie.
Linkage disequilibrium and genomic selection in pigs
Veroneze, R. - \ 2015
Wageningen University. Promotor(en): Johan van Arendonk; S.E.F. Guimarães, co-promotor(en): John Bastiaansen. - Wageningen : Wageningen University - ISBN 9789462574151 - 142
varkens - verstoord koppelingsevenwicht - loci voor kwantitatief kenmerk - genomica - populaties - kruising - inteeltlijnen - fokwaarde - selectief fokken - genetica - pigs - linkage disequilibrium - quantitative trait loci - genomics - populations - crossbreds - inbred lines - breeding value - selective breeding - genetics

Securing a sufficiently large set of genotypes and phenotypes can be a limiting factor when implementing genomic selection. This limitation may be overcome by combining data from multiple populations or by using information of crossbred animals. The research described in this thesis characterized linkage disequilibrium (LD) patterns in different pig populations and evaluated whether the consistency of LD between populations allows us to make predictions about the performance of genomic selection when multiple populations are included in the prediction and/or validation datasets.

In chapter 2 I evaluated the persistence of LD and patterns of LD decay of pure and crossbred pig populations using real data that was representative of the crossbreeding structure of pig production. The persistence of phase between the crosses and their parental populations was high, indicating that similar marker effects might be expected across these populations. Across the purebred populations the persistence of phase was low therefore higher density panels should be used to have the same marker-QTL associations across these populations.

In chapter 3, the well-known nonlinear model developed by Sved (1971) was compared against a an alternative, loess regression, to describe LD decay. The loess regression model was found to be less influenced by the lack of residual normality, independence and homogeneity of variance than the nonlinear regression model. The loess regression model resulted in more reliable LD predictions and can be used to formally compare the LD decay curves between populations.

Chapter 4 showed the utility of different reference sets (across- and multi-population) for the prediction of genomic breeding values, as well as the potential of using crossbred performance in genomic prediction. None of the accuracies obtained using across-population, or multi-population genomic prediction, nor the accuracies obtained using crossbred data, followed the expectations based on LD that was described in chapter 2. I showed that across-population prediction accuracy was negligible even when the populations had common breeds in their genetic background. The variable accuracies of multi-population prediction and moderate accuracy of prediction of crossbred performance appeared to be a result of the differences in genetic architecture between pure populations and between purebred and crossbred animals.

In chapter 5, a methodology that uses information from genome wide association analyses in the genomic predictions was developed and evaluated. The aim in chapter 5 was to let the genomic prediction model use information from the genetic architecture in single- and multi-population genomic prediction. I showed that using weights based on GWAS results from a combined population did result in higher accuracies of GBLUP in single- as well as in multi-population predictions.

In chapter 6 I placed my results in a broader context. I discussed about the theoretical and practical aspects of linkage disequilibrium in breeding and in the estimation of effective population size. I also discussed the application of genomic selection in a small population and in practical pig breeding, including the prospects of using whole genome sequence for genomic prediction.

The hybrid nature of pig genomes : unraveling the mosaic haplotype structure in wild and commercial Sus scrofa populations
Bosse, M. - \ 2015
Wageningen University. Promotor(en): Martien Groenen, co-promotor(en): Hendrik-Jan Megens; Ole Madsen. - Wageningen : Wageningen University - ISBN 9789462573000 - 253
dieren - varkens - dierveredeling - genomen - hybridisatie - sus scrofa - haplotypen - genomica - populaties - genetische variatie - animals - pigs - animal breeding - genomes - hybridization - haplotypes - genomics - populations - genetic variation - cum laude
cum laude graduation
Unravelling the genetics of iron status in African populations : candidate gene association studies
Gichohi-Wainaina, W.N. - \ 2015
Wageningen University. Promotor(en): Michael Zimmermann; Edith Feskens, co-promotor(en): Alida Melse-Boonstra; G.W. Towers. - Wageningen : Wageningen University - ISBN 9789462572102 - 198
ijzergebrekanemie - voeding - genetische factoren - eiwitten - volksgezondheid - voeding en gezondheid - populaties - afrika - iron deficiency anaemia - nutrition - genetic factors - proteins - public health - nutrition and health - populations - africa


Background: Investigating the manner in which genetic and environmental factors interact to increase susceptibility to iron deficiency, has the potential to impact on strategies to overcome iron deficiency as well as the development of biomarkers to monitor iron status in populations. Single nucleotide polymorphisms or genetic variants that may affect the composition and hence the functionality of proteins involved in iron metabolism have been the subject of recent genetic association studies. However, these investigations have not yet been carried out in African populations that differ genetically from populations of European ancestry and which bear the highest burden of iron deficiency. The overall aim of this thesis was to investigate the genetics of iron status in African populations using a candidate gene approach.

Methods: In order to evaluate the association between identified TMPRSS6 gene variants and iron status we conducted a systematic review with meta-analyses. We primarily searched the literature using the HuGE Navigator, Pubmed and Scopus databases for primarily genome wide association studies. Fixed effects meta-analysis was used to obtain summary estimates. Associations between reported variants and iron status as well as gene-gene and variant interactions that influence iron status were investigated in a female black South African cohort (n=686; range 32–86 years) which were part of the Prospective Urban and Rural Epidemiology (PURE) study. Concentrations of haemoglobin, serum ferritin, serum transferrin receptor and body iron stores were determined. Thirty SNPs were genotyped and passed all quality criteria. To investigate whether previously identified associations in populations of European ancestry are replicated in populations of African ancestry, we conducted candidate gene association studies. Twenty iron status-associated variants in 628 Kenyans, 609 Tanzanians, 608 South Africans and 228 African Americans were genotyped and associations investigated using haemoglobin and serum ferritin as outcome measures. Finally, we assessed the effect of TNF-α allele variants (TNF‒1031, TNF‒308) on malaria rates, the severity of malaria as indicated by haemoglobin concentrations at the time of presentation with febrile episodes and the association between Plasmodium infection and haemoglobin concentration in symptomless parasite carriers. We used data from a placebo-controlled trial which consisted of 612 Tanzanian children aged 6–60 months. Cox regression models were used in the primary analysis to account for multiple episodes per child.

Results: In our systematic review we included eleven studies on Caucasian populations, four on Asian populations and one study on an African-American population. Differences in minor allele frequencies (MAF) of 8 TMPRSS6 SNPs (rs855791, rs4820268, rs2111833, rs1421312, rs228921, rs228918, rs228919 and rs575620) across ethnic groups were observed; with the MAF of rs855791 being significantly higher in Asian populations than in Caucasians (0.55 vs 0.42). In the meta-analysis, the A allele of rs855791 was associated with lower haemoglobin and ferritin concentrations in all populations. This allele was also associated with increased serum transferrin receptor and transferrin concentrations. We observed similar associations for the G allele in rs4820268. In general, minor allele frequencies (MAF) from females in the PURE population were lower compared to those of males and females of European ancestry populations in the 1000 Genomes Project. In the TF gene, the SNP rs1799852 was associated with decreased serum ferritin (p=0.01) and body iron concentrations (p=0.03) and increased serum transferrin receptor (sTfR) concentrations (P=0.004), while rs3811647 was associated with transferrin receptor and body iron (both P=0.03) in a U-shaped manner. The chromosome 6 SNP allele combination (AAA) consisting of rs1799964 and rs1800629 both in TNF α and rs2071592 in NFKBIL1 was associated with higher odds for low serum ferritin concentrations (serum ferritin<15µg/L; OR:1.86 (95%-CI, 1.23-2.79)). The chromosome 22 SNP allele combination (GG) consisting of rs228918 and rs228921 in the TMPRSS6 gene was associated with lower odds for increased sTfR concentrations (sTfR>8.3mg/L; OR:0.79 (95%-CI,0.63-0.98). We successfully replicated reported significant associations with lowered haemoglobin concentrations for two loci in TMPRSS6 namely rs2413450 and rs4820268 and with increased haemoglobin concentrations for one locus in TF (rs3811658) when analysing the four populations of African ancestry. When ferritin was considered as an outcome measure, we replicated associations with increased ferritin concentrations in two loci namely, rs228918 in TMPRSS6 and rs1525892 in TF. No other significant associations were determined. Malaria rates were higher in Tanzanian children with the TNF‒1031CC genotype (rs1799964) compared to the AA genotype (crude hazard ratio (HR), 95%CI: 1.41 [1.01‒1.97], adjusted HR 1.31 [0.97‒1.76]y) but were lower in those with the TNF‒308AA genotype (rs1800629) (adjusted HR 0.13 [0.02‒0.63]) compared to those harbouring the wild type homozygous genotype.

Conclusions: This thesis demonstrates previously observed associations between TMPRSS6 gene variants and haemoglobin concentrations in European ancestry populations are replicated in African populations. Replication of results in other loci previously associated with iron status in European ancestry populations was not achieved. Additionally, minor allele frequencies of single nucleotide polymorphisms associated with iron status are generally higher in European ancestry cohorts compared to those of African ancestry populations. The lack of association of reported variants may indicate that novel loci are responsible for the heritability of iron status in African populations. We have additionally observed that TNF α variants increase malaria severity. Malaria is a major cause of iron deficiency in malaria endemic areas. Our finding emphasizes that to alleviate iron deficiency in malaria endemic areas prevention and treatment of malaria is necessary. This thesis highlights the need to conduct genetic association studies in African populations where iron deficiency is of utmost public health significance. In addition, investigations into the genetics of iron status are bound to contribute towards the development of biomarkers that are useful in the determination of iron status in areas of high inflammation burden.

Analyse trend en hotspots Alsemambrosia
Beringen, R. ; Odé, B. ; Vliet, A.J.H. van - \ 2014
ambrosia - ambrosia artemisiifolia - invasieve exoten - verspreiding van planten - kenmerken - onkruiden - analyse - detectie - populaties - nederland - invasive alien species - plant dispersal - traits - weeds - analysis - detection - populations - netherlands
Alsemambrosia is de meest voorkomende Ambrosiasoort in Nederland. Na bundeling van de gegevens van de belangrijkste bronnen van waarnemingen door, De Natuurkalender Wageningen UR, NDFF en is een analyse gedaan naar verspreiding en trend van Alsemambrosia in de periode 1975 t/m 2013. Tevens is op basis van de beschikbare gegevens een analyse gedaan naar de omvang van populaties in de periode 2000-2013.
A European tool for usual intake distribution estimation in relation to data collection by EFSA
Klaveren, J.D. van; Goedhart, P.W. ; Wapperom, D. ; Voet, H. van der - \ 2012
Parma : EFSA (Supporting Publications 2012: EN-300) - 42
voedselopname - populaties - variantie - food intake - populations - variance
The present document has been produced and adopted by the bodies identified above as author(s). In accordance with Article 36 of Regulation (EC) No 178/2002, this task has been carried out exclusively by the author(s) in the context of a grant agreement between the European Food Safety Authority and the author(s). The present document is published complying with the transparency principle to which the Authority is subject. It cannot be considered as an output adopted by the Authority. The European Food Safety Authority reserves its rights, view and position as regards the issues addressed and the conclusions reached in the present document, without prejudice to the rights of the authors.
Multiplex SSR analysis of Phytophthora infestans in different countries and the importance for potato breeding
Li, Y. - \ 2012
Wageningen University. Promotor(en): Evert Jacobsen, co-promotor(en): Theo van der Lee; D.E.L. Cooke. - S.l. : s.n. - ISBN 9789461732798 - 206
solanum tuberosum - aardappelen - plantenveredeling - plantenziekteverwekkende schimmels - phytophthora infestans - microsatellieten - populaties - ziekteresistentie - genetische merkers - moleculaire merkers - bio-informatica - genomica - plant-microbe interacties - potatoes - plant breeding - plant pathogenic fungi - microsatellites - populations - disease resistance - genetic markers - molecular markers - bioinformatics - genomics - plant-microbe interactions

Potato is the most important non-cereal crop in the world. Late blight, caused by the oomycete pathogen Phytophthora infestans, is the most devastating disease of potato. In the mid-19th century, P. infestans attacked the European potato fields and this resulted in a widespread famine in Ireland and other parts of Europe. Late blight remains the most important pathogen to potato and causes a yearly multi-billion US dollar loss globally. In Europe and North America, late blight control heavily relies on the use of chemicals, which is hardly affordable to farmers in developing countries and also raises considerable environmental concerns in the developed countries.
The structure of P. infestans populations can change quickly by migration, sexual recombination and sub-clonal variation. Migration and the reconvening of the two mating types considerably raised the level of genetic diversity in the global P. infestans population, leading to a more variable population with a presumed higher level of adaptability as compared to the previously, purely asexually, reproducing population. How can the P. infestans population efficiently be monitored with such diverse genotypes? A high-throughput, high-resolution and easy-handled set of markers would be favorable for this purpose. Few genetic markers, if any, have found such widespread use as SSRs. Sequencing allows the identification of large numbers of microsatellites by bioinformatics. So far, however, only a limited number of informative microsatellite loci had been described for P. infestans and none have been mapped. This thesis first describes the development and mapping of SSR markers in P. infestans and integration with other SSRs to generate a multiplex SSR set and its application in the population analysis of P. infestans from four countries are described with the developed multiplex SSRs. Finally, the use of this knowledge in resistance breeding of potato is shortly indicated and discussed.
Chapter 1 describes the historic population changes of P. infestans at the global level and the current population trends. It summarizes microsatellite as favorite molecular markers for studying pathogen population diversity and assesses monitoring of population dynamics in more detail for resistance breeding in potato.
The selection and identification of new SSR markers is presented in Chapter 2. From EST and genomic sequences from P. infestans we identified 300 non-redundant SSR loci by a bioinformatic screening pipeline. Based on the robustness, level of polymorphism and map position eight SSR markers were selected, which were assembled in two multiplex PCR sets and labeled with two different fluorescent dyes to allow scoring after single capillary electrophoresis.
This successful multiplex SSR approach encouraged the development of fast, accurate and high-throughput genotyping, in an one-step multiplex PCR method to facilitate worldwide screening of P. infestans populations. Published SSRs and the 8 new SSRs were integrated. All these SSR markers were re-evaluated and the 12 most informative SSRs were selected to set up a standard set for global application (Chapter 3). The 12-plex SSRs are distributed over different chromosomes, significantly increasing the resolution of genotyping compared to the previous set of 8 SSRs. The 12-plex SSRs were integrated to one-step fluorescence-based multiplex reaction, which plays a key role to facilitate highly paralleled genotyping and efficient dissection of the more complex P. infestans populations. This multiplex PCR for P. infestans populations is (i) simple, as only one PCR is needed to perform multi-locus typing with twelve markers; (ii) rapid, as the genotyping results can be available in 1 day; and (iii) reproducible and adapted to different laboratories. The genotyping data from different geographic populations were submitted to the Euroblight database. With the same SSR set and the bin set, a comparable global database can easily be achieved.
As indicated earlier, more recent analyses of P. infestans populations highlight the appearance of many new genotypes via migration and/or sexual recombination. To practice the newly developed 12-plex SSR set and dissect the current population structure, several P. infestans populations from 4 different continents were selected for analysis. These include Chinese (Chapter 4), Dutch (Chapter 5), Ecuadorian (Chapter 6) and Tunisian (Chapter 7) populations.
China has become the largest potato producing country not only for potato cultivation area but also in Megaton potato production. Interprovincial trade of consumption and seed potatoes is very important and frequent in China. Although both, the A1 and A2 mating types are found in China, to this date, no evidence of an active sexual cycle based on changes in allele frequency was found. With the ten SSRs, a large genotypic survey of in nation-wide collection of 228 P. infestans isolates was performed (Chapter 4). One of the three dominant clonal lineages CN-04 (A2) in this Chinese population was genetically similar to a major clonal lineage identified in Europe, called “Blue_13” with A2 mating type. It was not possible to critically assess the origin of this clonal lineage. This study is the first report of “Blue_13” outside Europe. The virulence spectrum of selected Chinese P. infestans isolates showed seven different virulence spectra varying from 3 to 10 differentials. The CN04 genotypes were identified as more aggressive and more virulent genotypes, one of whom had the full virulence pattern after using the potato differential set. Within the Chinese P. infestans population, the genotypes strongly clustered according to their six sampling provinces, which seems not to be influenced by the frequent interprovincial trading activities of seed potatoes. The mating type ratio and the SSR allele frequencies indicate that in China the contribution of the sexual cycle to P. infestans on population dynamics is minimal. It was concluded that the migration through asexual propagules and the generation of sub-clonal variation are the dominant driving factors behind the Chinese P. infestans population structure.
The Netherlands has a long history of population studies on local P. infestans isolates and a substantial amount of commercial potato varieties growing in the field. One decade (2000-2009) of isolate sampling in 5 different regions provided the basis for a good understanding of the population dynamics in the Netherlands (Chapter 5). The surveyed population revealed the presence of several clonal lineages and a group of sexual progenies. The major clonal lineage with A2 mating type is known as “Blue_13”, but also two distinct clonal lineages with A1 mating type in this study have been identified. This survey witnesses that the Dutch population was undergoing dramatic changes in the ten years under study. The most notable change was the emergence and spread of A2 mating type strain “Blue_13”. The results emphasize the importance of the sexual cycle in generating genetic diversity and the importance of the asexual cycle as the propagation- and dispersal mechanism for successful genotypes. In addition to the neutral SSR markers a molecular marker for the virulence of isolates on potato lines that contain the Rpi-blb1 R-gene has been developed. Using this Avr-blb1 marker and the corresponding virulence assay we report, for the first time, the presence of Rpi-blb1 breaker isolates in the Netherlands even before a Rpi-blb1 containing resistant variety was introduced. The 12 breaker isolates only occurred in sexual progeny. So far the asexual spread of such virulent isolates has been limited because of the absence of Rpi-blb1 containing varieties in the field.
Remarkably, on the other end of the world in the Andes, the region of potato origin, the situation is far less complex as far as P. infestans is concerned. There are more than 400 potato landraces in Ecuador and the planting habit by local farmers by traditional cultivation at small scale in the highlands is different from potato cultivation in other potato countries in North America or Europe (Chapter 6). Phytophthora isolates in Ecuador belong to two closely related species, P. infestans (on potato and tomato) and P. andina (on non-tuber bearing host), but SSR analysis of 66 isolates indicated that the two species are separated in two clearly distinguished genetic groups. Two ancient clonal lineages of P. infestans appeared to be dominant in Ecuador one is found only on tomato the other one only on potato. Within the potato isolates, but not in the tomato isolates, there is a large sub-clonal variation caused by (partial) polyploidization and loss of alleles.
In Tunisia, potato is cultivated in three to four partly overlapping seasons while tomato is grown either in greenhouses or as aerial crop in most potato producing regions. Chapter 7 revealed, among 165 isolates of five regions, the presence of a major clonal lineage (NA-01, A1 mating type, Ia mtDNA haplotype) that seems to consist of races that are relatively simple. Another highly genetic diverse group of isolates was found containing more complex races and isolates with both mating types. Season clustering indicated that at least some of the new genotypes generated by sexual reproduction overlapped between seasons and such a sexual progeny may play an important role in the next season epidemics. On tomato, mostly asexual progeny was identified with two mtDNA haplotypes but less nuclear genotypes, compared to potato. This study shows that the P. infestans population is currently changing, and the old clonal lineage is being replaced by a more complex, genetically diverse and sexually propagating population in two sub-regions in Tunisia. Despite the massive import of potato seeds from Europe, the P. infestans population in Tunisia is still clearly distinct from the European population.
Chapter 8 discusses the application of microsatellites in monitoring genetic diversity of late blight and the potential use in resistance breeding. Monitoring of the local P. infestans population for new virulent genotypes with the differential potato set in combination with screening for effector variation, allows early detection of adaptation of certain genotypes within the P. infestans population to particular resistance genes in a specific region. This provides the possibilities to determine which broad spectrum R-genes are still useful in order to adapt the control strategy by resistance breeding to the new situation. One way of doing that is to replace the existing varieties by other varieties with stacked non-broken R-genes obtained by marker assisted selection or to add additional R-genes to existing (R-gene containing) varieties by transformation. In a transgenic or cisgenic approach, additional broad spectrum R-genes could be added by re-transformation. As we have shown, the right R-gene management strategy in potato breeding, but also in potato production, should include the direct monitoring of local pathogen populations by using the differential set and the 12-plex SSR set.

Adapt, move or perish : the interaction of genetics and demography in fragmented populations under climate change
Cobben, M.M.P. - \ 2012
Wageningen University. Promotor(en): Rolf Hoekstra; Paul Opdam, co-promotor(en): Rene Smulders; Jana Verboom-Vasiljev. - S.l. : s.n. - ISBN 9789461731999 - 132
dendrocopos - habitats - habitatfragmentatie - biodiversiteit - populaties - klimaatverandering - adaptatie - genetica - demografie - modellen - verspreiding - habitat fragmentation - biodiversity - populations - climatic change - adaptation - genetics - demography - models - dispersal
In reactie op klimaatverandering verschuift van veel soorten het areaal, maar het is duidelijk dat dit voor lang niet alle soorten snel genoeg gaat. Habitatfragmentatie zal in het algemeen de noodzakelijke areaalverschuivingen vertragen. Er is geopperd dat de combinatie van areaalverschuivingen en de lokale aanpassing van soorten aan de veranderende omstandigheden hun overleving positief zal beïnvloeden
Voedselkeuzes en draagkracht: de mogelijke consequenties van veranderingen in de draagkracht van Nederlandse kustwateren op het voedsel van schelpdieretende wad- en watervogels
Smit, C.J. ; Brinkman, A.G. ; Ens, B.J. ; Riegman, R. - \ 2011
Den Burg : IMARES (Rapport / IMARES Wageningen UR C155/11) - 197
wadvogels - zeevogels - populaties - voedselketens - voedsel - voedselvoorziening - ecosystemen - habitats - natuurbeleid - kustwateren - voedselvoorkeuren - wildbeheer - waddenzee - noordzee - wadden sea birds - sea birds - populations - food chains - food - food supply - ecosystems - nature conservation policy - coastal water - food preferences - wildlife management - wadden sea - north sea
De Waddenzee en de Noordzeekustzone zijn aangewezen als Natura2000-gebieden. Naast een verplichting tot instandhouding is voor de Waddenzee een verbeterdoelstelling geformuleerd voor de schelpdieretende vogelsoorten Eider (als broedvogel en als niet-broedvogel), Topper, Kanoet, Scholekster en Steenloper (voor deze soorten als niet-broedvogel). Voor de Noordzeekustzone zijn voor schelpdieretende kustvogels en voor de aangewezen habitattypen alleen behoudsdoelstellingen geformuleerd. Anno 2010 voldoen de populaties van de Topper, de Kanoet en de Steenloper aan de Instandhoudingsdoelstellingen voor de Waddenzee. De aantallen van de Eider en de Scholekster liggen lager dan de geformuleerde doelstellingen. In de Noordzeekustzone liggen de aantallen Zwarte Zee-eenden, Eiders en Scholeksters onder de geformuleerde Instandhoudingsdoelstellingen. Voor de Kanoet werden deze gehaald tussen 1999-2000 en 2003-2004 maar de actuele situatie is onduidelijk. Gedurende de laatste decennia waren verscheidene factoren van belang voor de aantalsontwikkeling van de meeste schelpdieretende vogelsoorten. Het toenmalige Ministerie van LNV (nu EL&I) heeft in 2008 aan IMARES vragen gesteld die in het kader van een zogenaamd BO-project moesten worden beantwoord. Voor de belangrijkste soorten schelpdieretende vogels (de hierboven genoemde soorten plus de Zwarte Zeeeend) gaat het om de volgende vragen: In hoeverre is het benodigde voedsel aanwezig? Is het beschikbare voedsel van voldoende kwaliteit? Is het preferente voedsel beschikbaar en bereikbaar? Krijgen de vogels voldoende gelegenheid om het voedsel ook te bemachtigen (onder invloed van ecologische en antropogene factoren)? Deze basisvragen zijn door het Ministerie voor de 6 te onderzoeken vogelsoorten (Eider, Zwarte Zeeeend, Toppereend, Scholekster, Kanoet en Steenloper) vertaald naar de in Hoofdstukken 3 t/m 8 weergegeven kennisvragen per soort. Deze richten zich vooral op de voedselecologie van de genoemde schelpdieretende soorten. De centrale vraag die in dit rapport wordt besproken is in hoeverre de condities binnen de Waddenzee en de Noordzeekustzone van invloed zijn of kunnen zijn op de populatieomvang van de genoemde soorten. De belangrijkste factoren die hierop invloed kunnen hebben zijn habitatgeschiktheid en voedselvoorziening. Habitatgeschiktheid is in deze gebieden vooral gekoppeld aan de aanwezigheid van geschikte leefgebieden en verstoring, voedselvoorziening aan de beschikbaarheid van voldoende hoeveelheden geschikte prooidieren.
Contraceptie als methode in het beheer van hoefdierpopulaties
Kuiper, M.W. ; Wieren, S.E. van - \ 2010
Wageningen : Wageningen Universiteit (REG-rapport ) - 54
hoefdieren - natuurgebieden - contraceptie - populaties - ungulates - natural areas - contraception - populations
Bezorgdheid over dierenwelzijn en praktische problemen met lethale methoden hebben geleid tot de ontwikkeling van contraceptiemiddelen om hoefdierpopulaties te beheren. Vroege studies hebben enkele chemische sterilisatiemiddelen getest, maar de meeste daarvan zijn niet geschikt gebleken om in het wild levende hoefdieren mee te behandelen. Sommige zijn onpraktisch vanwege de noodzaak van herhaalde toediening of de grote volumes die geïnjecteerd moeten worden om effect te verkrijgen (o.a. (synthetische) hormonen), terwijl andere afvallen vanwege negatieve bijwerkingen op de gezondheid van behandelde dieren (o.a. DES, levonorgestrel). Een ander probleem van de meeste chemocontraceptiemiddelen is hun resistentie tegen biologische afbraak, waardoor de middelen via de voedselketen overgedragen kunnen worden of zich ophopen in het milieu. Het meest veelbelovende chemocontraceptiemiddel is waarschijnlijk de GnRH-agonist leuprolide, dat wel biologisch afbreekbaar is.
Geïnduceerde resistentie biedt kansen voor plaagbestrijding
Messelink, G.J. - \ 2010
Onder Glas 7 (2010)2. - p. 54 - 55.
populaties - geïntegreerde plagenbestrijding - verdediging - vruchtgroenten - komkommers - micro-organismen - plantextracten - trialeurodes vaporariorum - tetranychidae - biologische bestrijding - glastuinbouw - groenten - populations - integrated pest management - defence - fruit vegetables - cucumbers - microorganisms - plant extracts - biological control - greenhouse horticulture - vegetables
Planten kunnen zich verdedigen tegen plagen door te reageren op hun aanwezigheid met het aanmaken van gifstoffen en verteringsremmers, waardoor dit de ontwikkeling van het plaagorganisme remt. Er zijn mogelijkheden om deze plantreactie van te voren te induceren met chemische stoffen, plantextracten, micro-organismen of andere planteneters. In komkommer is gebleken dat deze weerstand geïnduceerd kan worden met witte vlieg, waardoor de biologische bestrijding van spint sterk verbetert
Genetic conservation of endangered animal populations
Oliehoek, P.A. - \ 2009
Wageningen University. Promotor(en): Johan van Arendonk, co-promotor(en): Piter Bijma. - [S.l.] : S.n. - ISBN 9789085853503 - 113
dieren - genetische diversiteit - inteelt - bedreigde soorten - bedreigde rassen - stamboom - populatiegenetica - populaties - conservering - ex-situ conservering - animals - genetic diversity - inbreeding - endangered species - endangered breeds - pedigree - population genetics - populations - conservation - ex situ conservation
KB-WOT Fisheries Research; programme for 2009
Dickey-Collas, M. ; Beek, F.A. van - \ 2009
IJmuiden : Centrum voor Visserijonderzoek (CVO report 09.003) - 35
visserij - kennisoverdracht - klimaatverandering - milieueffect - vis vangen - populaties - visserijbeheer - onderzoeksprojecten - fisheries - knowledge transfer - climatic change - environmental impact - fishing - populations - fishery management - research projects
LNV programme WOT 5 covers the execution of statutory tasks (WOT) in fisheries carried out by DLO. Part of the KB programme, presented in this report, contains resources earmarked to maintain and develop the expertise needed to carry out the WOT programme. As well as maintaining expertise, innovation is an important part of the programme. The programme is also part of the Wageningen UR Kennisbasis and comes under the theme KB01: “Groene en blauwe ruimte”. This report describes the allocation and utilisation of the Kennisbasis budget in 2009. The available budget in 2009 is €621 000. The money is spent through projects, each of which is described here. The projects are split up into four priority research areas: A) Influence of changes in the environment on marine ecosystems, B) impact of fisheries on ecosystems, C) changing fishery management, D) maintenance and international exchange of key WOT expertise. These priority research areas have been developed with the agreement of LNV. All of these areas fall under the wider WUR kennisbasis themes.
Visie bijenhouderij en insectenbestuiving : analyse van bedreigingen en knelpunten
Blacquière, T. ; Steen, J.J.M. van der; Cornelissen, B. - \ 2009
Wageningen : Plant Research International (Rapport / Plant Research International 227)
apidae - honingbijen - bijenhouderij - honingbijkolonies - populatie-ecologie - populaties - kruisbestuiving - vegetatie - nederland - bijensterfte - honey bees - beekeeping - honey bee colonies - population ecology - populations - cross pollination - vegetation - netherlands - bee mortality
Al enkele jaren duiken in de pers berichten op over massale bijensterfte. Het sterven van honingbijenvolken wordt dan gelijk gezien aan het uitsterven van de soort. Juist ná beantwoording van vragen uit de Tweede Kamer komt LNV met een inventarisatie van de actuele situatie, om te weten of aanvullende maatregelen nodig zijn om de bijenpopulatie in stand te houden
An effective rotational mating scheme for inbreeding reduction in captive populations illustrated by the rare sheep breed
Windig, J.J. ; Lansbergen, L.M.T.E. - \ 2008
Animal 2 (2008)12. - ISSN 1751-7311 - p. 1733 - 1741.
dierveredeling - schapen - zeldzame rassen - populaties - inteelt - genetische diversiteit - fokkerijmethoden - agrobiodiversiteit - dieren in gevangenschap - kempisch heideschaap - animal breeding - sheep - rare breeds - populations - inbreeding - genetic diversity - animal breeding methods - agro-biodiversity - captive animals - kempen heath sheep - genetic contributions - selection - systems - strategies - programs - rates
Within breeds and other captive populations, the risk of high inbreeding rates and loss of diversity can be high within (small) herds or subpopulations. When exchange of animals between different subpopulations is organised according to a rotational mating scheme, inbreeding rates can be restricted. Two such schemes, a breeding circle and a maximum avoidance of inbreeding scheme, are compared. In a breeding circle, flocks are organised in a circle where each flock serves as a donor flock for another flock, and the same donor–recipient combination is used in each breeding season. In the maximum inbreeding avoidance scheme, donor¿recipient combinations change each year so that the use of the same combination is postponed as long as possible. Data from the Kempisch Heideschaap were used with computer simulations to determine the long-term effects of different breeding schemes. Without exchanging rams between flocks, high inbreeding rates (>1.5% per year) occurred. Both rotational mating schemes reduced inbreeding rates to on average 0.16% per year and variation across flocks in inbreeding rates, caused by differences in flock size, almost disappeared. Inbreeding rates with maximum inbreeding avoidance were more variable than with a breeding circle. Moreover, a breeding circle is easier to implement and operate. Breeding circles are thus efficient and flexible and can also be efficient for other captive populations, such as zoo populations of endangered wild species
Na herintroductie in 2002: Het gaat goed met de otter
Lammertsma, D.R. ; Kuiters, A.T. ; Niewold, F.J.J. ; Jansman, H.A.H. ; Koelewijn, H.P. ; Perez-Haro, M.I. ; Boerwinkel, M.C. ; Bovenschen, J. - \ 2008
Zoogdier 19 (2008)2. - ISSN 0925-1006 - p. 3 - 5.
otters - lutra lutra - zoogdieren - populatie-ecologie - populaties - wildbeheer - mammals - population ecology - populations - wildlife management
Na het uitsterven van de otter (Lutra lutra) in Nederland in 1989 werd in juli 2002 gestart met de herintroductie er van in de Kop van Overijssel (De Wieden). De otters zijn gevolgd. De populatie is flink toegenomen. Een toenemende bron van zorg is het aantal doodgereden otters in en rondom de uitzetgebieden. De otter heeft zich inmiddels door het hele uitzetgebied verspreid, alsmede een aantal aangrenzende gebieden. Ook wordt er bij geplande uitbreidingen rekening gehouden met de ecologische verbindingszones
Meer natuurlijke aanvallers voor maximale verdediging
Vlaswinkel, M.E.T. ; Elderson, J. - \ 2008
Groenten en Fruit. Algemeen 2008 (2008)13. - ISSN 0925-9694 - p. 44 - 45.
landbouw - gewassen - koolsoorten - ondergewassen - populaties - diversiteit - insecten - natuurlijke vijanden - uitzettingstechnieken - gewasbescherming - agriculture - crops - cabbages - catch crops - populations - diversity - insects - natural enemies - release techniques - plant protection
Functionele agrodiversiteit betekent omstandigheden creëren om de populatie van en verscheidenheid aan natuurlijke vijanden te vergroten. Die vijanden helpen mee om insecten te beheersen, bijvoorbeeld in spruitkool, onder het motto 'meer aanvallers voor een maximale verdediging'
Estimates of public health risks through import of Aedes albopictus via Dracaena's in the Netherlands : Investigation in the establlishment of Aedes albopictus : final report
Takken, W. ; Jacobs, F.H.H. - \ 2008
Wageningen : Laboratory of Entomology, Wageningen University - 10
culicidae - aedes albopictus - vestiging - populaties - monitoring - tuinbouwbedrijven - risicoschatting - volksgezondheid - nederland - establishment - populations - market gardens - risk assessment - public health - netherlands
Between September 2005 and October 2007 studies were done in six horticultural companies in the Netherlands to assess the presence of the exotic Aedes albopictus and to determine whether the species had become established. Adult mosquitoes were sampled with liberty plus carbon dioxide traps. The presence of eggs and larvae was studied by ovitraps and inspection of water collections. It is concluded that the current study did not demonstrate the establishment of Aedes albopictus in or around the companies that were studied. At the same time, over a period of 118 collection weeks the tigermosquito was found on 76 of the 118 weeks, suggesting a very regular introduction of the species from abroad. The frequent introductions are a cause for concern, as theoretically Aedes albopictus can survive in the Netherlands under current climate conditions
Report of the KB-WOT fisheries programme carried out in 2007
Dickey-Collas, M. ; Beek, F.A. van - \ 2008
IJmuiden : Centre for Fishery Research (CVO) (CVO report 08.006) - 22
visserij - kennis - klimaat - klimaatverandering - milieueffect - vis - populaties - onderzoek - visstand - fisheries - knowledge - climate - climatic change - environmental impact - fish - populations - research - fish stocks
This report documents the activities of the KB WOT fisheries programme in 2007. It gives the results, products and documents the experienced gained by staff through the programme. It also shows how the individual projects fit into the research priority areas of WOT fisheries programme for 2007. The financial spend is also documented in light of the experience and knowledge gained. The report also describes how KB WOT funding was used to maintain quality assurance for methods crucial for the WOT programme as a whole. Added value was achieved by using KB WOT funds within EU projects on climate variability, stock assessment methods, bycatch issues, management simulations and environmental impacts on fish populations and fisheries advice. Overall the 2007 programme should be viewed as a success in terms of stimulating innovation, looking forward for the requirements of LNV and society in the future, creating relevant products and publications and the underpinning the knowledge base of fisheries science at Wageningen IMARES.
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