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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    Why do some animals live in groups?
    Naguib, M. - \ 2018
    Wageningen : WURcast
    animal behaviour - animal ecology
    Eco-epidemiology of Bovine Tuberculosis (bTB) in an African savanna : The conflict between traditional pastoralist adaptations and disease transmission in the modern era
    Dejene, Sintayehu Workeneh - \ 2017
    Wageningen University. Promotor(en): H.H.T. Prins, co-promotor(en): W.F. de Boer; I.M.A. Heitkönig. - Wageningen : Wageningen University - ISBN 9789463436588 - 119
    cattle diseases - tuberculosis - disease transmission - pastoralism - animal ecology - risk factors - ethiopia - rundveeziekten - tuberculose - ziekteoverdracht - pastoralisme - dierecologie - risicofactoren - ethiopië

    Bovine tuberculosis (bTB) is a zoonotic disease, and remains a cause of concern for livestock, wildlife and human health, especially in Ethiopia. It is a contagious disease, so close contact between animals or sharing of feed between infected and non-infected animals are major risk factors for transmission. Thus, improving the understanding of the factors that promote contact between hosts (i.e., livestock animals but also wild ruminants) is critical for limiting bTB transmission in pastoral, multi-host communities. I found that the older the age of the cattle and the lower the body condition, the higher the chance of a positive bTB test result at the individual animal level. Moreover, at herd level, herd size, contact with wildlife, and the interaction of herd size and contact with wildlife were identified as significant risk factors for bTB prevalence in cattle in Ethiopia. Further to what is already known from the past studies, I found that the probability of contact with wildlife was positively influenced by herd size, through herd movement. As larger herds moved more and grazed in larger areas, the probability of grazing in an area with wildlife and contact with either infected cattle or infected wildlife hosts increased; this also increased the chances for bTB infection. I detected a possible ‘dilution effect’ in bTB, where a higher evenness of mammal species reduced the probability of bTB occurrence. This dilution effect might be caused by encounter reduction. Because the encounter rate is proportional to the distribution of the host species; evenness would then capture the probability of encounter between pathogens and each host species. Thus, species evenness can be an appropriate measure of biodiversity to explain disease risk. I also showed that bTB prevalence was positively associated with the invasion of the plant Prosopis (Prosopis juliflora), maybe due to the loss in host species evenness and the increase in cattle movement as a consequence of the loss of palatable grasses in Prosopis-infested areas. Moreover, social contacts between herd owners are also important, as I found that herds with a greater number of edges in a (social) network had more connections in the livestock transfer network, increasing the probability of becoming infected with bTB. Thus, cultural components like large herd size and social contacts are at odds with the global One Health rationale to reduce bTB.

    Seals in motion : how movements drive population development of harbour seals and grey seals in the North Sea
    Brasseur, Sophie Marie Jacqueline Michelle - \ 2017
    Wageningen University. Promotor(en): P.J.H. Reijnders, co-promotor(en): G.M. Aarts. - Wageningen : Wageningen University - ISBN 9789463436120 - 176
    seals - phoca vitulina - halichoerus grypus - pinnipedia - population biology - animal ecology - wadden sea - netherlands - zeehonden - phoca vitulina - halichoerus grypus - pinnipedia - populatiebiologie - dierecologie - waddenzee - nederland
    The harbour seal Phoca vitulina and the grey seal Halichoerus grypus have been inhabitants of the Wadden Sea since millennia. Prehistoric findings indicate the presence of both species around 5000 BC. This changed dramatically in the mid Middle-Ages as around 1500 AC, the grey seal disappeared from the Wadden Sea as a consequence of persecution. With growing hunting pressure, especially in the 20th century and concurrent habitat destruction and pollution, the harbour seals reached all time low numbers in the 1970’s. Banning the hunt in countries around the southern North Sea, limiting pollution and protection from disturbance allowed the harbour seals to slowly recover and the grey seals to return to the Wadden Sea. In this thesis the population trends and inherent dynamics of the recovery for both species is described. Also the movements of individual animals are studied to explain possible mechanisms.
    Spatial distribution and habitat preference of harbour seals (Phoca vitulina) in the Dutch North Sea
    Aarts, Geert ; Cremer, Jenny ; Kirkwood, Roger ; Wal, Jan Tjalling van der; Matthiopoulos, Jason ; Brasseur, Sophie - \ 2016
    Den Helder : Wageningen Marine Research (Wageningen Marine Research rapport C118/16) - 43
    seals - phoca vitulina - spatial distribution - habitats - animal ecology - marine ecology - north sea - netherlands - zeehonden - phoca vitulina - ruimtelijke verdeling - habitats - dierecologie - mariene ecologie - noordzee - nederland
    African elephant in a cleft stick : choosing between starving or dying from thirst in arid savanna
    Wato, Yussuf - \ 2016
    Wageningen University. Promotor(en): Herbert Prins, co-promotor(en): Ignas Heitkonig; Frank van Langevelde. - Wageningen : Wageningen University - ISBN 9789463430005 - 126
    loxodonta africana - starvation - thirst - savannas - arid zones - animal ecology - mortality - drought - loxodonta africana - uithongering - dorst - savannen - aride klimaatzones - dierecologie - mortaliteit - droogte

    Elephant population studies have become important especially because of the long standing perception that high elephant densities have negative impact on vegetation and other wildlife species. Thus, in areas of high elephant density, managers attempt to re-distribute them or keep their numbers low through provision of water, translocation or culling. These approaches are thought to keep the population within the limits that can be sustained by the ecosystem, termed “the ecological carrying capacity”, a management option hinged on equilibrium theory. Equilibrium systems are considered stable, with resources and the animals that depend on them being at balance with each other. This stability is rarely the case in tropical savannas where the rule appears to be “a flux of nature” rather than “a balance of nature”.

    Tropical savannas, where over half of the African elephant live, are prone to constant environmental fluctuations, especially prolonged droughts, and hence there is a growing understanding that populations of wildlife species and their communities are rarely at equilibrium. Therefore, it is critical to understand how the constant environmental flux in this system affects wildlife populations and the implication for their management. In this thesis, the central focus is to investigate the role of drought occurrences on elephant population dynamics in tropical savannas. To address this question, it is important to have a good understanding of the historical changes of elephant population in relation to drought events and the ecology of elephant in semi-arid savannas - their distribution and density, their movements and behaviour. For the historical data, I analysed the best existing long-term data in Africa of wild elephant population that has been consistently monitored for over 40 years where life histories of over 3000 wild individual elephant are known, at Amboseli National Park in Kenya. In addition, I also analysed geo-referenced elephant mortality data collected daily for 10 years from Tsavo Conservation Area. Further, I analysed 2 years data from 8 GPS collared African elephant to investigate their movement response to seasonal water and forage distribution in Tsavo Ecosystem.

    First, I investigated the temporal effects of drought duration (number of consecutive dry months) and intensity (amount of rainfall) on elephant population structure in Amboseli National Park, Kenya. The result corroborates findings from past studies that calves (<2years) are more susceptible to drought caused mortality and the risk of dying decreased with age. A new finding in this study reveals that the effect of drought induced mortality for the adult elephant is sex and age dependent, with males older than 25 years being less likely to die as compared to females of the same age. This new result is because of the resolution of analysis in this study which focused on the length and severity of drought as opposed to past studies that restricted their analysis to seasonal and inter-annual differences in rainfall pattern. As they grow older and sexually mature, the foraging range of male elephant increase and they begin to take more risks and disperse to unfamiliar habitats to seek for quality forage and mates. Generally, foraging strategies between sexes in many species are more pronounced during periods of food scarcity, and the driving force in the differences appears to be driven by energy need requirements, reproductive status of an individual, body sizes and the social context, all of which differ between sexes.

    In the next study, I investigated the spatial pattern of elephant mortality in relation to drought occurrences in Tsavo National Park using MaxEnt. The results shows that elephant carcasses were aggregated and elephant mortality was negatively correlated with four months cumulative precipitation prior to death, forage availability and distance to water, while local elephant density showed a positive correlation. This finding rules out dehydration as the cause of elephant mortality in Tsavo as the river where the carcasses were aggregated is perennial. Furthermore, forage availability was low close to water sources and did not show a significant difference close to or further away from the river despite high elephant density around the river. Hence, these elephant mortalities may have occurred as a result of starvation.

    I went further to focus on two main limiting resources for elephants, namely forage and water, and their effect on elephant-habitat utilization in semi-arid savannas. I first investigated how water source distribution affect elephants’ seasonal movement patterns. Results indicate that male elephant moved maximally 20 km away from the nearest water source in the dry season while the female elephant foraged to a maximum of about 10 km and only moved further than this distances in the wet season. The strong directionality of elephant movement from a distance of 15km towards water sources (rho > 0.5) as they re-visited their watering source in the dry season suggest that elephant have information on location of the water sources.

    Next, I investigated the factors that determine selection of a foraging site for elephant with a focus on forage nutrients or biomass. Because of their large body size, it is thought that elephant can survive on a less nutritious but high biomass of forage. The results from this study shows that elephant selected foraging site based on forage biomass in dry seasons, whereas they selected areas with higher nutrients in the wet season. Moreover, females selected sites with a higher forage biomass as compared to males. This result may be explained by the difference in social organisation and foraging strategies between the sexes. In the previous studies on human-elephant conflict, for instance, male elephant raided crops more than the mixed herd, perhaps to seek for high quality forage.

    Together, the four studies in this thesis strongly suggest that elephant starve to death in prolonged drought contrary to the past studies that reported that adult elephant are less affected by drought. Even though prolonged droughts usually result in higher elephant mortalities, the resilience of semi-arid savannas may perhaps be as a result of these deaths that release the system from high browsing pressure and give it a window to regenerate. If that is the case, then drought induced elephant mortality may be a better way to regulate elephant numbers than culling. This finding strongly suggests that semi-arid savannas may in fact be a non-equilibrium system sustained by growth and crashes of herbivore populations. Maintaining the system as natural as possible may therefore keep elephant populations in savannas sustained for posterity. The modern day park managers have daunting challenges such as mass elephant deaths in drought, increased human-wildlife conflicts or changes in wildlife use of the landscape which may all be symptoms of wrong management interventions taken in the past or negative impacts of anthropogenic activities that have tipped the natural functioning of a non-equilibrium system. Therefore, park managers should undergo regular trainings on new conservation techniques and they should apply evidence-based science to make informed long term decision.

    Onderzoek naar het voorkomen van de wasbeer in Nederland
    Grift, E.A. van der; Lammertsma, D.R. ; Jansman, H.A.H. ; Wegman, R.M.A. - \ 2016
    Wageningen : Wageningen Environmental Research (Wageningen Environmental Research rapport 2764) - 43
    procyon lotor - zoögeografie - dierecologie - nederland - duitsland - procyon lotor - zoogeography - animal ecology - netherlands - germany
    In opdracht van het Bureau Risicobeoordeling en onderzoeksprogrammering (BuRO) van de Nederlandse Voedsel- en Warenautoriteit (NVWA) is het voorkomen van de Wasbeer (Procyon lotor) in Nederland en de Duitse grensstreek in beeld gebracht en onderzocht of er sprake is van gevestigde populaties. Vooralsnog zijn er geen aanwijzingen dat er binnen Nederland sprake is van een lokaal gevestigde populatie. In de Duitse grensstreek met Nederland zijn de aantallen nog relatief laag, maar als de huidige populatietrends doorzetten, verandert dat naar verwachting op korte termijn. Hoewel concrete gegevens ontbreken, is de kans groot dat inmiddels, op een aantal plaatsen, gevestigde populaties dicht bij de Nederlandse landsgrens voorkomen.
    Illuminating a bird’s world : effects of artificial light at night on avian ecology
    Jong, Maaike de - \ 2016
    Wageningen University. Promotor(en): Marcel Visser, co-promotor(en): K. Spoelstra. - Wageningen : Wageningen University - ISBN 9789462578098 - 177
    birds - animal behaviour - animal ecology - illumination - artificial light - night - fitness - biological rhythms - vogels - diergedrag - dierecologie - belichting - kunstlicht - nacht - fitheid - biologische ritmen
    Bruinvis verhongert soms in zee vol vis : tien jaar onderzoek naar menu zeezoogdier
    Leopold, Mardik - \ 2016
    phocoena - animal behaviour - animal ecology - population ecology - feeding behaviour - feeding ecology - marine biology
    Wild geese of the Yangtze River : their ecology and conservation
    Zhang, Y. - \ 2016
    Wageningen University. Promotor(en): Herbert Prins; Fred de Boer; L. Cao. - Wageningen : Wageningen University - ISBN 9789462576049 - 147
    geese - anatidae - anser - animal ecology - wildlife management - nature conservation - hydrology - habitat selection - rivers - china - ganzen - anatidae - anser - dierecologie - wildbeheer - natuurbescherming - hydrologie - habitatselectie - rivieren - china

    Habitat selection is a process in which organisms decide to choose a suitable site for nesting, roosting or foraging. The question where the organisms are, and when they will leave are two of the fundamental questions frequently asked by ecologists. Habitat selection is affected by various abiotic and biotic determinants, varying over different spatial and temporal scales. In addition, an animal’s body size, determining its daily demands and its digestion capacity, plays an important role in foraging and habitat selection. This is because forage quality often decreases with increasing forage quantity. Therefore, herbivores often face a trade-off between forage quality and quantity. Although studies on habitat selection have offered substantial insights into the effect of various ecological factors, myriad effects of habitat and its’ surrounding are still not clearly understood, as former studies concerning this topic normally focus on a single species or a single spatial scale.

    Migrating goose species are herbivorous with more or less similar habitat requirements and hence often mix in the field. Studying habitat selection of different goose species is attractive as they are from the same guild but differ in body size. In this thesis, I study the effects of various variables on habitat selection of different Anatidae species over different spatial scales, answering the question how ecological and anthropogenic variables affect Anatidae species habitat selection and population sizes and if these effects vary over different spatial scales.

    First, I studied the habitat selection of Anatidae species under the condition with and without interference competition using an experimental approach in Chapter 2. To do this, I offered geese and ducks foraging patches with various swards heights. My results showed that all three species acquired the highest nitrogen intake at relatively tall swards (on 6 or 9 cm, but not on 3 cm) when foraging in single species flocks in the functional response experiment. When they were offered foraging patches differing in sward height with and without competitors, their mean percentage of feeding time did not change, whereas all species increased their percentage of time being vigilant except for the dominant swan goose. All species utilized strategies that increased their peck rate on patches across different sward heights when foraging together with other species, resulting in the same instantaneous and nitrogen intake rate than when foraging in a single species flocks. My results suggest that variation in peck rate over different swards height permits Anatidae herbivores to increase nitrogen intake under competition to compensate for the loss of intake, illustrating the importance of behavioural plasticity in heterogeneous environments when competing with other species for resources.

    In Chapter 3, using a correlative field study, I analysed the habitat selection of two differently sized grazing goose species at site level. I found that both species selected lower lying area where the swards became recently exposed, due to receding water levels. However, the smaller species was more sensitive to this elevation gradient. Moreover, sward height negatively affected both species habitat selection with a stronger effect on the smaller species. This result highlighted the importance of body size on facilitating species coexistence and habitat segregation. Not in agreement with the results from most experimental studies, I found that nitrogen content did not influence habitat selection of both species. This conflicting result suggests that additional factors should be carefully considered when applying outcomes from experimental studies to field situations.

    In Chapter 4, I studied habitat selection of the two goose species at a lake level by analysing the effect of ecological and anthropogenic variables. My results supported the individual-area relationship as only patch area had a significant effect on both species habitat selection, and other variables that were related to food availability and disturbance, were not significant. In addition, a facilitation effect of grazing livestock on geese habitat selection was detected, indicating that larger grazing herbivores can facilitate geese foraging by removing the taller and lower quality food from the top. As patch area size in wetlands is directly linked to water levels fluctuations, this result demonstrated that modifying hydrological regimes can enlarge the capacity of wetlands for migratory birds.

    In Chapter 5, I further expanded my study area to the flood plain level of the Yangtze, testing for the effect of various abiotic and biotic variables on several Anatidae species habitat selection and population trends. I showed that slope and climate factors were the most important ones affecting habitat selection and distribution of Anatidae species. Furthermore, I demonstrated that the current protection policies may not stop the declining population trends but might buffer to some extent against a rapid decline in numbers in wetlands with a higher level protection status. This result points out that the conservation effectiveness is still low and larger conservation efforts are urgently needed to maintain the Anatidae populations, especially in wetlands with a lower level protection status. I recommend several protection measures to stop the decline of Anatidae species in wetlands of the Yangtze River flood plain and I called for more research efforts in this area in particularly, but also at a larger scale, the entire East Asian-Australasian Flyway.

    In Chapter 6, I synthesized these results and draw conclusions from the preceding chapters, and highlighted the importance of spatial scales when studying the effect of abiotic and biotic variables on animals’ habitat selection. I also propose to modify hydrological regimes, aimed at creating enhanced habitat and improved forage accessibility conditions over the entire wintering period for herbivorous birds species in the Yangtze River flood plain. In summary, this thesis offers a framework for the effects of various variables on habitat selection and population sizes of herbivorous Anatidae species over different spatial scales, and a scientific basis for policy-makers and managers to enhance the efficiency of conservation actions in wetlands along the Yangtze River flood plain and also for similar ecological systems.

    Bat activity at offshore wind farms LUD and PAWP in 2015
    Lagerveld, S. ; Jonge Poerink, B. ; Vries, P. de; Scholl, M.M. - \ 2016
    Den Helder : IMARES (Report / IMARES C001/16) - 32
    chiroptera - wind farms - offshore - monitoring - animal ecology - north sea - netherlands - chiroptera - windmolenpark - offshore - monitoring - dierecologie - noordzee - nederland
    Zweven boven de afgrond : gieren in Afrika ernstig bedreigd
    Nijland, Rik ; Buij, R. - \ 2015
    WageningenWorld (2015)4. - ISSN 2210-7908 - p. 22 - 25.
    accipitridae - bedreigde soorten - uitsterven - afrika - ziekten - pathogenen - dierecologie - accipitridae - endangered species - extinction - africa - diseases - pathogens - animal ecology
    Ze worden opgegeten, vergiftigd door boeren en stropers en verwerkt in traditionele medicijnen. Afrikaanse gieren zijn daardoor in vijftig jaar met 80 procent achteruitgegaan. Als de gieren het laten afweten, worden rottende karkassen mogelijk verspreidingshaarden van ziekten die gevaarlijk zijn voor mens en dier.
    Individual-area relationship best explains goose species density in wetlands
    Zhang, Y. - \ 2015
    animal ecology
    Use MCMCglmm to analysis the effect of ecological and human disturbance on two goose species densities in wetland.
    Moths in illuminated nights : articificial night effects on moth ecology
    Geffen, K.G. van - \ 2015
    Wageningen University. Promotor(en): Frank Berendse, co-promotor(en): Elmar Veenendaal; Roy van Grunsven. - Wageningen : Wageningen University - ISBN 9789462572300 - 116
    lepidoptera - kunstlicht - nacht - belichting - dierecologie - effecten - geometridae - diergedrag - lepidoptera - artificial light - night - illumination - animal ecology - effects - geometridae - animal behaviour
    Almost all terrestrial species on earth have evolved to be active in a certain part of the day, and as a result are adapted to certain light conditions. Diurnal species are active under high light intensities (the period known as the photophase, i.e. daytime), nocturnal species are active in low light intensities (the period known as the scotophase, i.e. night), and crepuscular species are in between, active in twilight (i.e. dusk and dawn). During the course of evolution, light intensity has been a very reliable cue for the on- and offset of activity of all these species, but recently, the night is no longer dark per definition. Mankind illuminates the night with artificial light sources, which has led to world-wide large-scale alterations of night-scapes. Levels of light pollution continuously rise, currently with approximately 6% per year on average
    Inteelt onder Sallandse korhoenders : de genetische gevolgen van een kleine populatieomvang
    Groot, G.A. de; Jansman, H.A.H. ; Bovenschen, J. ; Laros, I. ; Meyer-Lucht, Y. ; Hoglund, J. - \ 2014
    Wageningen : Alterra, Wageningen-UR (Alterra-rapport 2599) - 47
    tetrao tetrix - geïntroduceerde soorten - fauna - dierecologie - habitats - genetisch evenwicht - salland - tetrao tetrix - introduced species - fauna - animal ecology - habitats - genetic equilibrium - salland
    Recent werd Alterra gevraagd om de resultaten van onderzoek dat de afgelopen jaren door verschillende instituten is uitgevoerd te bundelen en te integreren om een antwoord te krijgen op de vraag of het korhoen duurzaam voor Nederland behouden kan worden en op welke manier behoud mogelijk is (Jansman et al. 2014). Het voorliggende rapport is een aanvulling op dit basisrapport, waarin dieper wordt ingegaan op de effecten die de sterke afname in populatieomvang heeft gehad op het verloop van genetische processen van de korhoenpopulatie, en de gevolgen die dit kan hebben voor de algehele vitaliteit van de populatie, en diens reproductievermogen in het bijzonder. In dit onderzoek is duidelijk geworden dat de Nederlandse korhoenpopulatie al in 2010 genetisch zeer sterk was verarmd. In 2013, toen slechts zeven individuen overgebleven waren, bleek de variatie nog verder teruggelopen, ook op genen die van belang zijn voor een goed functionerend immuunsysteem
    Ecologie stengelaaltjes
    Vreeburg, P.J.M. ; Dees, R.H.L. ; Doorn, J. van; Boer, F.A. de - \ 2014
    Lisse : Praktijkonderzoek Plant & Omgeving, Business Unit Bloembollen, Boomkwekerij & Fruit - 27
    bloembollen - plantenplagen - nematoda - ditylenchus dipsaci - detectie - methodologie - identificatie - levenscyclus - dierecologie - ornamental bulbs - plant pests - nematoda - ditylenchus dipsaci - detection - methodology - identification - life cycle - animal ecology
    Bij een besmetting met stengelaaltjes (Ditylenchus dipsaci) in bolgewassen is de economische schade groot, omdat het een quarantaine-organisme betreft. Binnen deze aaltjessoort zijn verschillende rassen te onderscheiden, met elk een andere waardplantenreeks. Het tulpenstengelaaltje heeft de breedste waardplantenreeks en is daarmee ook het meest gevreesde ras. Om onderzoek te doen naar de overleving, verspreiding en bestrijding van stengelaaltjes, zijn technieken nodig voor rassenidentificatie, in stand houding en vermeerdering van de aaltjes. Het ontbreken van geschikte technieken vormt een grote belemmering voor het onderzoek. Dit project heeft nieuwe methoden opgeleverd voor de bewaring en detectie van (tulpen-)stengelaaltjes.
    Natural variation in memory formation among Nasonia parasitic wasps : from genes to behaviour
    Hoedjes, K.M. - \ 2014
    Wageningen University. Promotor(en): Louise Vet; Marcel Dicke, co-promotor(en): Hans Smid. - Wageningen : Wageningen University - ISBN 9789461739483 - 191
    nasonia - hymenoptera - geheugen - leervermogen - genetische factoren - dierecologie - diergedrag - genomen - nasonia - hymenoptera - memory - learning ability - genetic factors - animal ecology - animal behaviour - genomes

    The ability to learn and form memory has been demonstrated in various animal species, ranging from relatively simple invertebrates, such as snails and insects, to more complex vertebrate species, including birds and mammals. The opportunity to acquire new skills or to adapt behaviour through learning is an obvious benefit. However, memory formation is also costly: it can be maladaptive when unreliable associations are formed and the process of memory formation can be energetically costly. The balance between costs and benefits determines if learning and memory formation are beneficial to an animal or not. Variation in learning abilities and memory formation between species is thought to reflect species-specific differences in ecology.

    This thesis focused on variation in the number of trials required to form long-term memory (LTM). LTM is considered the most stable and durable type of memory, but also the most costly, because it requires protein synthesis. Many animal species require multiple learning experiences, which are spaced in time, to form LTM. This allows re-evaluation of information before an animal invests in costly LTM. There is, however, variation in the number of trials that animal species require to induce LTM formation. A number of insect species, including a number of parasitic wasp species, form LTM after only a single learning experience. Parasitic wasps can learn odours that guide them towards suitable hosts for their offspring, so-called oviposition learning. Substantial differences in LTM formation are observed among closely related species of parasitic wasps, which provides excellent opportunities for comparative studies. Both ecological and genetic factors involved in variation in LTM formation have been studied in this project. A multidisciplinary approach is essential to understand the evolution of variation in LTM formation, because the interaction between genes and environment shapes learning and memory formation.

    LTM formation was studied in closely related species of the genus Nasonia. These small parasitic wasps (~2 mm in length) lay their eggs in various species of fly pupae and differences in the ecology of the four known species of this genus have been described. A high-throughput method for olfactory conditioning was developed in which the wasps associated an odour, either chocolate or vanilla, with the reward of a host. A T-maze olfactometer was designed for high-throughput testing of memory retention. Using these methods, variation in memory retention was observed between three Nasonia species. Both N. vitripennis and N. longicornis form a long-lasting memory after a single conditioning trial, which lasts at least 5 days. Nasonia giraulti, on the other hand, lost its memory after 1 to 2 days after a single conditioning trial. Further studies focused on the difference between N. vitripennis and N. giraulti, which was most pronounced. By inhibiting LTM with transcription and translation inhibitors, it was confirmed that N. vitripennis forms this type of memory after a single conditioning trial. LTM is visible 4 days after conditioning in N. vitripennis. Nasonia giraulti does not form LTM after a single conditioning trial. Long-lasting memory is only formed after two trials, with a 4-hour interval between them. This difference in LTM formation makes N. vitripennis and N. giraulti excellent model species to study both ecological and genetic factors involved in this difference.

    Ecological factors such as the value of the reward and the reliability of the learned association have been shown to affect memory formation in a number of animal species. A recent study on oviposition learning in two parasitic wasp species demonstrated that LTM formation depends on the host species, i.e. the reward offered during conditioning. LTM was formed when a host with a higher quality was offered, but not when a host of lower quality was offered. The effect of host quality on memory retention of N. vitripennis and N. giraulti was tested. Either a large host, Calliphora vomitoria, a medium-sized host, Lucilia sericata, or a small host, Musca domestica, was offered during conditioning. These hosts were observed to differ significantly in their quality, i.e. in the number of parasitoid offspring that emerged and the size of the offspring. There was, however, no effect of host species on memory retention in either Nasonia species. These results suggest that host quality is not important for LTM formation in N. vitripennis and N. giraulti. This observation shows that ecological factors that are important for memory formation in one species may not be important for another species.

    The genetic basis of memory formation is highly conserved among distant animal phyla. A large number of genes involved in LTM formation have been identified in genetic model organisms, including fruit flies, honeybees, the California sea hare, mice and rats, and the zebra finch.Genetic factors responsible for natural variation in LTM formation between species are currently unknown, however. Two approaches were used to study genetic factors responsible for the difference in LTM formation between N. vitripennis and N. giraulti. The first approach took advantage of the unique possibility to interbreed Nasonia species. Hybrid offspring of N. vitripennis and N. giraulti did not form LTM after a single conditioning trial, similar to N. giraulti. The dominant LTM phenotype of N. giraulti was then backcrossed into the genetic background of N. vitripennis for up to 5 generations. Using a genotyping microarray analysis and subsequent confirmation experiments, we detected two genomic regions (quantitative trait loci – QTLs) that both reduce long-lasting memory, but not completely remove this memory. These results indicate that multiple QTLs regulate the difference in LTM formation between the two Nasonia species. Concluding, our approach has provided insights in the genomic basis of a naturally occurring difference in LTM formation between two species. Excellent opportunities for fine-scale QTL mapping are available for the genus Nasonia. This will allow identification of decisive regulatory mechanisms involved in LTM formation that are located in the two genomic regions detected in this study.

    The second approach took advantage of next-generation sequencing techniques that allow transcriptome-wide studies of gene expression levels. RNA from heads of N. vitripennis and N. giraulti was collected before conditioning and immediately, 4 hours, or 24 hours after conditioning. This RNA was sequenced strand-specifically using HiSeq technology, which allows detection of sense and antisense transcripts. Various genes, from a number of different signalling pathways known to be involved in LTM formation, were uniquely differentially expressed after conditioning in N. vitripennis. These genes are likely involved in the ongoing process of LTM formation in this species. A number of other genes with a known role in LTM formation,including genes involved in dopamine synthesis and in the Ras-MAPK and PI3K signalling pathways, were uniquely differentially expressed in N. giraulti. These genes may have a role in a LTM inhibitory mechanism in this species. Antisense transcripts were detected for a number of known memory genes, which may indicate a role inregulation of transcription, alternative splicing, or translation. This study is the first to compare gene expression patterns after conditioning between two species that differ in LTM formation. The results provide promising candidate genes for future studies in which the regulation of these genes, the function of specific splice variants, and spatial expression patterns in the brain should be studied to understand how these genes are involved in the regulation of LTM formation.

    Learning and memory formation have an important role in animal and human behaviour.Novel and valuable insights on both ecological and genetic factors responsible for variation in LTM formation have been revealed by the research presented in this thesis. Integrating ecological factors and genetic factors is essential, as genes are the level on which ecological factors can drive the evolution of variation in learning and memory formation. The genus Nasonia has offered excellent opportunities for ecological research as well as unique opportunities for studies on genomic and genetic factors, which were addressed by comparing closely related species that differ in memory formation. This thesis provides the basis for the identification of genomic differences responsible for the difference in memory formation between Nasonia species, but it also characterized the consequences of these genomic differences on gene expression. The genetic basis of learning and memory formation are highly conserved among distant animal species and insights from this thesis are likely applicable to other animal species and humans, as well.Altogether, these small parasitic wasps allow us to understand and value differences in memory formation.

    Search performance and the spatial resource distribution
    Huisman, T.J. - \ 2014
    Wageningen University. Promotor(en): Herbert Prins, co-promotor(en): Fred de Boer; Frank van Langevelde. - Wageningen : Wageningen University - ISBN 9789461739391 - 100
    fauna - dierecologie - migratie - foerageren - telemetrie - diergedrag - fauna - animal ecology - migration - foraging - telemetry - animal behaviour
    In de afgelopen decennia heeft het onderzoek naar bewegingspatronen in de ecologie een vlucht genomen. Door de ontwikkeling van alsmaar kleinere gps-transmitters en chips worden tegenwoordig de bewegingsgegevens van een enorm aantal dieren en soorten opgeslagen. Naast deze enorme toename in beschikbare gegevens is er een ontwikkeling geweest in de theoretische modellen die besproken en gebruikt worden in de ecologische literatuur. Al deze ontwikkelingen tezamen vormen de nieuwe subdiscipline van de zogenaamde bewegingsecologie en het onderzoek in dit proefschrift valt precies onder deze noemer.
    ‘Meneer groot wild’ neemt afscheid : Groot Bruinderink vraagt zich af hoeveel ruimte we groot wild willen en kunnen geven (interview met Geert Groot Bruinderink)
    Scharroo, J. ; Groot Bruinderink, G.W.T.A. - \ 2013
    Bionieuws 2013 (2013)19. - ISSN 0924-7734 - p. 2 - 2.
    wildbeheer - dierecologie - fauna - diergedrag - natuurbeleid - maatschappelijk draagvlak - deskundigen - wildlife management - animal ecology - fauna - animal behaviour - nature conservation policy - public support - experts
    Groot wild groeit uit de toegewezen gebieden, maar draagvlak voor verbindingszones ontbreekt. Wildecoloog Geert Groot Bruinderink: ‘maar we moeten er wel iets mee"
    Telemetry studies in harbour porpoises - An overview of the technical and practical state of the art
    Lucke, K. - \ 2013
    Den Helder : IMARES (Report / IMARES Wageningen UR C043/13) - 21
    phocoenidae - diergedrag - telemetrie - satellietkarteringen - dierecologie - phocoenidae - animal behaviour - telemetry - satellite surveys - animal ecology
    Information on the life functions and ecology of harbour porpoises is still scarce. Only a limited number of animals are available for research in controlled situations. Satellite tracking allows to gather information on individual movements of harbour porpoises, hence providing direct insight into the individual lifestyle of a free-ranging animal. Moreover, satellite telemetry is a powerful method for directly identifying the cause-effect relationship between anthropogenic activities and the animal’s behaviour. Harbour porpoises have been tagged with satellite transmitters already for almost two decades. This document is intends to provide a comprehensive overview of the relevant aspects of telemetry studies in harbour porpoises in Dutch waters and also give an overview of the latest technical developments in this field. Based on this information the strategy for further development and use of telemetry in harbour porpoises can be shaped.
    De Nederlandse Bijen
    Belgers, J.D.M. - \ 2013
    Bijenhouden 2013 (2013)juni. - ISSN 1877-9786 - p. 4 - 5.
    apidae - honingbijen - nederland - bestuivers (dieren) - drachtplanten - dierecologie - determinatietabellen - identificatie - boekbesprekingen - apidae - honey bees - netherlands - pollinators - pollen plants - animal ecology - keys - identification - book reviews
    Het Jaar van de Bij (2012) was een groot succes. Alom aandacht voor zowel de honingbij als de wilde bij. Bijenhotels rezen het afgelopen jaar als paddenstoelen uit de grond; veel mensen weten nu het verschil tussen honingbij, wilde (solitaire) bij en wesp. Hoogtepunt voor veel bijenliefhebbers was de presentatie van het boek ‘De Nederlandse Bijen’op 13 december 2012 bij Naturalis in Leiden. Na onze vooraankondiging in januari hier een bespreking van een kenner.
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