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.

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Ecologische kwaliteit ook door bijen bepaald; bijen in het openbaar groen (2)
Koster, A. - \ 2000
Groen : vakblad voor groen in stad en landschap 56 (2000)4. - ISSN 0166-3534 - p. 1 - 11.
Apidae - Apis - honingbijen - groene zones - recreatiegebieden - openbare parken - publieke tuinen - milieubeleid - ecologie - diergedrag - gewoonten - openbaar groen - honey bees - green belts - amenity and recreation areas - public parks - public gardens - environmental policy - ecology - animal behaviour - habits - public green areas
De auteur stelde een richtlijn op om de ecologische kwaliteit van het groen te waarderen. Bijen zeggen veel over beheer en milieu
Egelonderzoek in Europa
Grift, E.A. van der; Huijser, M.P. - \ 2000
Zoogdier 11 (2000)2. - ISSN 0925-1006 - p. 12 - 17.
erinaceus europaeus - erinaceidae - ecologie - dierecologie - diergedrag - gewoonten - territorium - habitats - milieu - landschap - mortaliteit - doodsoorzaken - verkeer - monitoring - migratie - verspreiding - conferenties - ecology - animal ecology - animal behaviour - habits - territory - environment - landscape - mortality - causes of death - traffic - migration - dispersal - conferences
De interessantste zaken van de Fourth International Hedgehog Workshop (28-29 januari, Zweden). Aandacht voor o.a. onderzoek naar monitoring, doodsoorzaken (waaronder wegen), leefgebieden, invloed van de mens op het landschap en de gevolgen voor egels
De consument, zijn zorgen en wensen
Hoog, C. de - \ 2000
Tijdschrift voor sociaalwetenschappelijk onderzoek van de landbouw 15 (2000)2/32/3. - ISSN 0921-481X - p. 70 - 72.
consumenten - houding van consumenten - consumentengedrag - consumentenvoorkeuren - gewoonten - consumentenaangelegenheden - consumers - consumer attitudes - consumer behaviour - consumer preferences - habits - consumer affairs
In het kort wordt ingegaan op de samenhang tussen de zorgen, de wensen en het gedrag van de moderne consument
Eikensterfte en de eikenprachtkever
Moraal, L.G. - \ 1998
Bosbouwvoorlichting 37 (1998)2. - ISSN 0166-8986 - p. 34 - 38.
bosschade - insecten - insectenplagen - bosbouw - Buprestidae - bomen - ecologie - diergedrag - gewoonten - overzichten - Nederland - forest damage - insects - insect pests - forestry - trees - ecology - animal behaviour - habits - reviews - Netherlands
Dit artikel is gebaseerd op IBN-rapport 320: De eikenprachtkever, Agrilus biguttatus, en eikensterfte: een literatuurstudie over aantastingen, levenswijze en verspreiding
Lake Victoria wetlands and the ecology of the Nile tilapia, Oreochromis niloticus Linne
Balirwa, J.S. - \ 1998
Agricultural University. Promotor(en): W.J. Wolff; P. Denny; R.M.M. Roijackers. - Rotterdam : Balkema - ISBN 9789054104117 - 247
hydrologie - limnologie - meren - plassen - hydrobiologie - biocenose - wetlands - polders - Percidae - rivierbaars - Cichlidae - Tilapia - Lutjanidae - ecologie - diergedrag - gewoonten - Centraal-Afrika - water - reservoirs - aquatische ecosystemen - hydrology - limnology - lakes - ponds - hydrobiology - biocoenosis - perch - ecology - animal behaviour - habits - Central Africa - aquatic ecosystems
<p>An ecological study of wetlands was undertaken in northern Lake Victoria (East Africa) between 1993 and 1996 with a major aim of characterising shallow vegetation-dominated interface habitats, and evaluating their importance for fish, in particular, for the stocked and socio-economically important <em>Oreochromis niloticus</em> LINNÉ (the Nile tilapia). From field and laboratory experiments, five major habitat types could be defined by the type of the dominant emergent macrophyte at the shore from the more than 40 identified plant species along a 110 km shoreline. These were: <em>Cyperus papyrus</em> L. (papyrus), <em>Phragmites mauritianus</em> Kunth (reeds), <em>Typha domingensis</em> Pers. (bulrush), <em>Vossia cuspidata</em> (Roxb.) (hippo grass), and the alien floating <em>Eichhornia crassipes</em> (Martius) Solms-Laubach (water hyacinth).</p></p>From digital data, considerable long term changes in the shoreline wetland landscape of the lake were discerned and appeared to be primarily associated with increasing human activity (e.g., agriculture, biomass harvests) which had resulted into a 5 % reduction of wetland cover. Inspite of the absence of a well developed euhydrophyte community (e.g., <em>Potamogeton</em> and <em>Ceratophyllum</em> ), and increasing infestations with <em>E. crassipes</em> mats, the width of the littoral zone was established by secchi transparency as being about 50 - 70 m away from the shallow (less than 1 m deep) vegetation fringe sloping to between 2 and 4 m in depth at its outer fringe. Hydrological influences associated with seasonal changes (the alternation of rainy with dry periods) explained most of the observed variation in abiotic (e.g., Si, tot.-P, soluble reactive-P, NO <sub>3</sub> -N, pH, temperature) and biotic (phytoplankton, macrofauna, fish) factors, but there was also significant (p &lt; 0.05) variation due to vegetation, distance from the shore out towards open water and interaction effects between these factors.</p></p>At least 30 species of fish were identified from the shallower (2.5 m) vegetated habitats in contrast to 10 species from the deeper (4 - 8 m) open water habitats. There were other significant (p &lt; 0.05) spatial and temporal differences in habitat use by fish. Species diversity was dominated by haplochromine species but three stocked species (the Nile perch, <em>Lates niloticus</em> L., <em>O. niloticus</em> and <em>Tilapia zilli</em> ) contributed at least 90% of the estimated numerical and biomass densities of which, the Nile tilapia was the most important component making up 45 - 65 % of the biomass of all fish. Season was a major factor in size-related abundance patterns but generally, most of the Nile tilapia biomass was associated with <em>Phragmites-Vossia-Typha</em> -dominated habitats which were also important for small (&lt;15.0 cm) and juvenile fish.</p></p>The shallow vegetated habitats were found to be ecologically important for the Nile tilapia for sheltering and feeding, and, it was also found that Lake Victoria Nile tilapia were significantly more fecund (with 3723 ± 147 eggs.female <sup>-1</SUP>) and had a higher condition index than populations of the species in Lake Kyoga (also stocked) and Lake Albert (a native habitat). It was inferred that these differences could be a result of a better nutritional base in Lake Victoria where the species was shown to be omnivorous (with detrital and animal foods as major dietary items) contrary to the previously believed herbivorous (phytoplankton) habits. Successional patterns associated with water hyacinth and the strong hydrological influences on shallow vegetated habitats imply that basin disturbances could therefore be a major threat to water quality and the fisheries.</p>
DASSIM, een simulatiemodel voor de evaluatie van verkeersscenario's: calibratie en validatie
Apeldoorn, R.C. van; Verboom, J. ; Nieuwenhuizen, W. - \ 1997
Delft : Rijkswaterstaat DWW - 59
verspreiding - Mustelidae - ecologie - diergedrag - gewoonten - overheidsdiensten - transport - ongevallen - dieren - fauna - schade - wegen - computersimulatie - simulatie - simulatiemodellen - Nederland - kalibratie - diergemeenschappen - menselijke invloed - dispersal - ecology - animal behaviour - habits - public services - accidents - animals - damage - roads - computer simulation - simulation - simulation models - Netherlands - calibration - animal communities - human impact
Eikenprachtkever, Agrilus biguttatus, en eikensterfte: een literatuurstudie over aantastingen, levenswijze en verspreiding
Moraal, L.G. - \ 1997
Wageningen : IBN-DLO - 24
Quercus - bosschade - insecten - insectenplagen - bosbouw - Buprestidae - bomen - ecologie - diergedrag - gewoonten - Nederland - forest damage - insects - insect pests - forestry - trees - ecology - animal behaviour - habits - Netherlands
Ganzen, grazers op trek langs de vorstgrens
Dekkers, H. ; Ebbinge, B. - \ 1997
Haarlem : Schuyt & Co - ISBN 9789060974469 - 156
Anser - ganzen - ecologie - diergedrag - gewoonten - biogeografie - fauna - migratie - geese - ecology - animal behaviour - habits - biogeography - migration
Vleeskuikenmoederdieren stofbaden in strooisel
Rooijen, J. van; Haar, J.W. van der - \ 1996
Praktijkonderzoek voor de Pluimveehouderij 7 (1996)4. - ISSN 0924-9087 - p. 14 - 18.
diergedrag - ecologie - gewoonten - ligstro - vleeskuikenouderdieren - groepshuisvesting - animal behaviour - ecology - habits - litter - broiler breeders - group housing
Om vast te stellen of het welzijn van vleeskuikenouderdieren in groepskooien lager is dan bij grondhuisvesting moet men weten hoe de dieren zich in beide systemen gedragen. In groepskooien is geen strooisel aanwezig. De vaderdieren zouden bij grondhuisvesting de moederdieren op het strooisel zo lastig kunnen vallen dat deze moederdieren feitelijk ook niet over strooisel kunnen beschikken. In dit onderzoek bleken deze moederdieren zich wel degelijk op het strooisel op te houden en er ook te stofbaden
Ecology and behaviour of the African buffalo: social inequality and decision-making.
Prins, H.H.T. - \ 1996
London : Chapman & Hall (Wildlife ecology and behaviour series 1) - ISBN 9780412442407 - 363
Bovidae - ecologie - diergedrag - gewoonten - sociaal gedrag - Afrika - ecology - animal behaviour - habits - social behaviour - Africa
What are the benefits that animals gain from living in a social group? This question has been the primary focus of the author's ecological interest. After many years of original and innovative research on the African buffalo, particularly at Lake Manyara in northern Tanzania, Herbert Prins has now summarized the results of much of this widely-respected work in this fascinating book. While advantages in reduction of the risks of predation or in increased efficiency of foraging on certain types of resources are now widely recognized, until now there has been less attention paid to the idea of the animals themselves as `information centres' and the extent to which the individual may be able to make use of information gathered by conspecifics, adjusting its own behaviour in response. Such a case-study has wide implications for research on social structure and organization in other species, and these are explored within the book.
De mogelijke verstoring van eekhoorns door verkeer: een oriënterend onderzoek. Project Versnippering, deel 25
Nieuwenhuizen, W. ; Apeldoorn, R.C. van - \ 1995
Delft : Rijkswaterstaat, Dienst Weg- en Waterbouwkunde - 41
Sciuridae - eekhoorns - voortplanting - bosbouw - diergedrag - gewoonten - adaptatie - dieren - territorium - habitats - milieu - nadelige gevolgen - schade - vibratie - geluid - warmte - motorvoertuigen - verkeer - transport - Nederland - Sciurus vulgaris - squirrels - reproduction - forestry - animal behaviour - habits - adaptation - animals - territory - environment - adverse effects - damage - vibration - noise - heat - motor cars - traffic - Netherlands
Interspecific competition, predation, and the coexistence of three closely related neotropical armoured catfishes (Siluriformes - Callichthyidae)
Mol, J.H.A. - \ 1995
Agricultural University. Promotor(en): J.W.M. Osse. - S.l. : Mol - ISBN 9789054854388 - 174
dieren - relaties - Siluridae - ecologie - diergedrag - gewoonten - Neotropisch gebied - animals - relationships - ecology - animal behaviour - habits - Neotropical Region
<p>Tropical ecosystems are renowned for their high biodiversity with many closely related species living together. Alpha diversity of tropical freshwater fishes is also extremely high, as exemplified by the cichlid fauna of the Great African lakes and the neotropical characins. Since Hutchinson in 1959 posed his often quoted question: "Why are there so many animals?", factors affecting species diversity have been important subject of study and discussion in ecology. Given the limits of the physical environment, two different biological processes are probably responsible for most of the organization of equilibrial communities: competition and predation. Critics of the view that competition and predation play a major role in structuring communities argued that several factors keep populations below a level where competition or predation could be strong. Reviews of the literature on field experiments designed to demonstrate the influence of competition and predation revealed that only 9% of the studies were conducted in the tropics.<p>The tropical rainforest is one of the most stable environments in the world. Temperature and humidity are almost constant, but important fluctuations in the water level of streams and swamps occur. Extreme conditions limiting population densities and leading to the extinction of populations are often hard to imagine. The high number of species will lead to complex biological interactions. More studies on competition and predation in the stable environment of the tropical rainforest are necessary to evaluate the importance of both processes in structuring communities.<p>A case study is presented concerning three medium-sized armoured catfishes of the family Callichthyidae: <em>Callichthys callichthys, Hoplosternum littorale</em> and <em>Hoplosternum thoracatum.</em> In order to evaluate the influence of competition and predation on the catfish communities, four factors were investigated in detail: 1) geographical distribution, 2) diet overlap, 3) reproductive seasonality and nest-site differentiation, and 4) predation.<p>In Suriname (South America), both <em>C. callichthys</em> and <em>H. thoracatum</em> occur all over the country. Both catfishes are abundant in both coastal plain swamps with standing water and rainforest creeks in the interior with running water. <em>Hoplosternum littorale,</em> on the other hand, is restricted in its distribution to coastal plain swamps. Salinity tolerance experiments demonstrated that one-week old larvae of <em>H. littorale</em> could not survive in electrolyte-poor water (e.g. rain water). The 'clear water' of rainforest creeks in the interior may be compared to slightly contaminated distilled water with very low electric conductivity. Larvae of both <em>C. callichthys</em> and <em>H. thoracatum</em> survived and developed further in rain water. The pattern of distribution in Suriname can be considered as a model of the distribution of the three catfishes in South America. In South America, <em>H. littorale is</em> not only conspicuously absent from clear water streams draining the weathered Precambrium Guyana and Brazilian Shields, but also from 'black water' streams with humic acids and also a low conductivity (e.g. the Rio Negro). Within the Amazon drainage system <em>H. littorale</em> seems restricted to 'white water' streams loaded with Andean sediments and with a higher conductivity than both clear water and black water. In Suriname, actual syntopy of the three species occurs in coastal plain swamps. In rainforest creeks of the interior <em>C. callichthys</em> and <em>H. thoracatum</em> occur syntopically. Consequently interspecific competition among the three callichthyids is possible.<p>Analysis of the stomach contents of larvae, juveniles and adults of the three armoured catfishes revealed no significant interspecific differences in the diet of larvae, juveniles and adults. However, ontogenetic differences in diet composition among larvae, juveniles and adults where significant for all three catfishes. Larvae of <em>C</em> . <em>callichthys, H. littorale</em> and <em>H. thoracatum</em> fed almost exclusively on Rotifera, Cladocera and Copepoda. The stomach contents of juveniles were more diverse and included micro-crustacea, insect larvae, aquatic insects and some detritus. Adults ingested large quantities of detritus which probably reflected the inability of large fish to seperate effectively benthic invertebrates from substrate. Chironomid larvae where found in large numbers in the stomach of adult specimens. The short alimentary tract of the three catfishes and the structure of its wall make it improbable that these fishes are able to assimilate detrital nonprotein amino acids. The posterior part of the intestine is thin-walIed and has a respiratory function. The anterior digestive portion is relatively short. Morphologically the three callichthyids are adapted to a benthic way of life and a diet of soft-bodied aquatic invertebrates. The similarity in the diet and their bottomdwelling habit provide the basis for grouping the three armoured catfishes into one ecological guild. Competitive interactions are expected to be potentially strong among members of a guild.<p>Male <em>C. callichthys, H. littorale</em> and <em>H. thoracatum</em> construct and guard a floating bubble nest in flooded swamps. Although the habit of constructing a floating bubble nest probably evolved as an adaptation to the oxygen-depleted environment of tropical standing waters, some of the characteristics of the nests of <em>C.</em><em>callichthys</em> and <em>H. thoracatum</em> may have evolved as a response to the unpredictability of the fluctuations in water level and water velocity in rainforest creeks. The conspicuous nests allow the study of the temporal pattern of breeding, the spatial distribution of the nests and the differentiation of the nest-site microhabitat among the three species. Daily surveys in coastal plain swamps revealed a similar, bimodal breeding season in the three catfishes. Nests were observed in both the short and long rainy season. The bimodal breeding pattern in Suriname is probably related to the unreliability of the rainfall in the short rainy season of December-January. In French Guiana the rains of December-January usually do not fail and an unimodal breeding season of <em>H. littorale is</em> found. Significant differences in nest macrohabitat selection were found among the three callichthyids. Nests of <em>H. littorale</em> were built in herbaceous swamps, while <em>C</em> . <em>callichthys</em> and <em>H. thoracatum</em> nested in swamp forest under trees. The two forest nesting species differed in the microhabitat at the nest site. Nests of <em>C</em> . <em>callichthys</em> were constructed in extremely shallow water and in holes of tree roots and earth. Nest densities in the selected habitat were low in <em>C.</em><em>callichthys</em> and <em>H. littorale,</em> but relatively high in <em>H</em> . <em>thoracatum.</em> Nest-site differentiation in the rainy season (the main feeding period) may prevent competitive exclusion among the three catfishes.<p>The potential predation pressure on eggs, larvae and juveniles of <em>H. thoracatum</em> was estimated by combining laboratory predation rates of 24 predator species (both invertebrates and vertebrates) with the density of the predators in the swamp as determined by chemofishing with rotenone. The contribution of a particular predator species to the total predation pressure on <em>H.</em><em>thoracatum</em> was determined to a large extent by the density of the predator in the swamp. Seemingly innocuous predators with low or moderate predation rates in the laboratory may be extremely important in the swamp due to their abundance. Smallsized fishes and aquatic invertebrates are probably major predators of early developmental stages of <em>H. thoracatum.</em> The potential predation pressure on eggs is high, but the aggressive nest guarding behaviour of the male catfish and concealment of the nests probably protects the eggs effectively from most aquatic predators. Larvae are not guarded by the male and the potential impact of the 24 predators on the larvae of <em>H. thoracatum</em> is large. Although the experiments were performed with <em>H.</em> thoracatum there is no good reason to expect important differences in predation rates on larvae of the three armoured catfishes. Even if only 2.5 % of the potential predation will be realized due to other prey available, the high mortality of early developmental stages of <em>H. thoracatum</em> (and <em>C. callichthys</em> and <em>H. littorale</em> ) in the swamp could be easily explained as the effect of predation. Potential predation pressure and the number of predators that were able to prey on <em>H. thoracatum</em> sharply declined with increasing age (size) of the juvenile catfish. The heavy armour of bony plates and stout pectoral spines protect older juveniles and adults from most potential predators. The high potential predation pressure in the swamps and the low density of juvenile catfish at the end of the rainy season suggest that predation is important in structuring these catfish communities.<p>Although larvae of the three armoured catfishes <em>C. callichthys</em> , <em>H. littorale</em> and <em>H. thoracatum</em> show differences in tolerance to electrolyte-poor water, the three species occur together in coastal swamps. Interspecific diet overlap is very high, and the three catfishes show no differentiation in their breeding season and diel pattern of activity. Ontogenetic changes in the defense mechanisms of armoured catfishes result in a situation in which both predation and competition exert control at different times in the life cycle. Predators probably kill most of the larvae and juveniles, leaving only a few individuals to escape and reach adulthood. If the number of escapes would exceed the number of adult deaths, the populations eventually become sufficiently dense to compete. However, in this situation nesthabitat segregation may prevent competitive exclusion of one <em></em> of the three species <em>.</em>
Carabid beetles in a changing environment.
Boer, P.J. den; Dijk, Th.S. van - \ 1994
Wageningen : Wageningen Agricultural University (Wageningen Agricultural University Papers 94-6) - ISBN 9789067543934 - 30
Carabidae - ecologie - diergedrag - gewoonten - milieu - nadelige gevolgen - milieueffect - menselijke activiteit - Nederland - drenthe - ecology - animal behaviour - habits - environment - adverse effects - environmental impact - human activity - Netherlands
Evolutionary aspects of acoustic communication in Ribautodelphax planthoppers (Homoptera, Delphacidae)
Winter, A.J. de - \ 1994
Agricultural University. Promotor(en): R.J. Post. - S.l. : De Winter - ISBN 9789054852292 - 123
Auchenorrhyncha - ecologie - diergedrag - gewoonten - communicatie tussen dieren - geluiden - geluidsleer - evolutie - fylogenie - oorsprong - fylogenetica - ecology - animal behaviour - habits - communication between animals - sounds - acoustics - evolution - phylogeny - origin - phylogenetics
<p>Delphacidae (Homoptera), commonly referred to as planthoppers, are herbivores, which usually feed on grasses and sedges. During sexual behaviour males and females communicate by exchanging low-frequency vibrational signals, which are transmitted through the substrate, normally the host plant. This thesis deals with the acoustic behaviour of one planthopper genus, <em>Ribautodelphax,</em> where both male and females have been found to produce species-specific calls, which differ between species in temporal parameters. As in other planthoppers, the acoustic signals of males and females are rather different. Male calls are more complicated, and consist of at least two structurally different elements, a variable number of 'chirps', followed by a 'buzz' of variable length, hence termed the 'chirp-section' and the 'buzz-section', respectively. The female call consists of a series of simple pulses, which differs between species in interpulse interval length ( <em>IPI</em> ), signal duration, and modulation of pulse repetition rate within the signal.<br/>This study was aimed at answering the following central, interrelated questions:<p>1. Do planthopper calls have a function in species recognition (sexual isolation) and mate preference?<br/>2. What forces have caused differentiation of acoustic signals?<br/>3. What is the relationship between divergence in acoustic signals and speciation?.<p>It was confirmed that, during the first phase of the sexual behaviour (the socalled distant calling phase), these calls are especially important in bringing potential mating partners together. Males called first, and mating-receptive females responded acoustically. The male then started searching actively for the female and continued to exchange calls with her, during which the female remained sedentary until the male came in close range. Females only responded to conspecific male calls when they are virgin and old enough. In populations of two closely related species, the development of female responsiveness with age corresponded fairly well with that of insemination levels, which shows acoustic response levels to be good indicators of mating receptiveness.<p>At close range (courtship in the strict sense), males remained acoustically active, but the female signal length and calling frequency tended to decrease, and some females ceased responding altogether. This suggests that during courtship the male call serves in maintaining and enhancing the female's receptiveness, and that the female call is less important. At this stage of sexual behaviour females appeared to be rather cautious, and usually only allowed copulation after many refusals. Courtships were clearly shorter when a female was confined with two males instead of one. Females seemed not to mate randomly with the available males, leaving open the possibility of some form of sexual selection. In the absence of other obvious cues, it seems possible that females might prefer males on the basis of their acoustic signals, but possibly due to the limited number of observations no trend in preference was found. However, females did not actively choose between males, nor did males behave in any way aggressively towards each other. After both males called initially, usually only one male continued courtship, leaving the possibility that males first assess their relative attractiveness or social status m their calls.<p>Different closely related <em>Ribautodelphax</em> species performed the same behaviours during courtship, but differed more or less in the frequencies of transitions between behavioural events. A more distantly related species deviated more strongly in transition frequencies, as well as by exhibiting a behavioural element not shared by the other species.<p>Many combinations of <em>Ribautodelphax</em> species are known to be able to produce viable and fertile interspecific hybrids under no choice conditions. However, when both conspecific and heterospecific partners are available, interspecific matings rarely take place, if at all. After rearing two species together for 10 generations no indication was found of introgression having occurred. Thus, recognition of conspecifics takes place before mating. Most females exposed to playbacks of heterospecific male calls responded about as well as to conspecific calls. In contrast, males were found to approach only playbacks of conspecific female calls, or, in a two- way choice experiment, chose significantly more often for the conspecific call. In an additional experiment males were continously exposed to either a conspecific or a heterospecific female playback call during their development from egg to adult. After this treatment both types of males preferred the conspecific female call over the heterospecific one, but males with experience of the conspecific call did this significantly more often. Males primed with the heterospecific female call performed similarly to acoustically naive males. This shows that recognition of conspecific female signals by males is largely genetic, but can be improved to some extent by previous experience of the conspecific signal, whereas the recognition mechanism is not affected by heterospecific signals. Thus, the acoustic communication between the sexes forms at least part of the specific mate recognition system of these species. Apparently, species recognition in <em>Ribautodelphax</em> results primarily from the male preference for conspecific female calls. This is a surprising result, because females only mate once during their lives, in contrast to males. In the absence of any obvious male parental investment, apart from costs involved in searching, the females would be expected to be more selective.<p>At close range, most interspecific courtships observed did not result in copulation, which is likely to be a by-product of within-species choosyness by females towards acoustic or non- acoustic performances of males. Such interspecific encounters are unlikely to occur under natural conditions, because at that stage recognition has already taken place.<p>Artificial bi-directional selection for large and small <em>IPI</em> s in the female call of <em>R. imitans</em> was very successful, resulting in non-overlapping distributions of the character after only five generations. The mean of realized heritability estimates of all selection lines over this period was above 80%, and still above 50% over 10 generations. <em>IPI</em> proved to be a polygenic character, controlled by at least six independently segregating genetic factors. Other female call characters, like signal duration, and modulation of pulse repetition rate within the signal exhibited correlated responses. After the experiment a significant degree of symmetrical assortative mating was found in mate preference tests between males and females from oppositely selected lines, but co-selected males did not show a significant preference for female playback calls with <em>IPI</em> s close to those occurring in their selection lines. Some characters of the chirp-section of the male call also appeared to exhibit a correlated change, suggesting that male and female call characters do not evolve independently. It seems possible that the assortative mating among individuals of the selection lines is due to female preference for the changed male call parameters, rather than to the preference of males for changed <em>IPI</em> s in the female calls.<p>The genetic control of male call characters in <em>R. imitans</em> was studied by father-sons regression. Heritability estimates of the chirp-section characters were statistically significant (0.44-0.54), in contrast to those of the buzz-section (0.09-0.28). Phenotypic, genetic, and environmental correlations calculated among male call characters suggest that chirp-section and buzz-section characters vary independently. One chirp-section character, number of chirps, appeared to be influenced by sex-linked loci. This means that the heritability estimate obtained by father-sons regression probably underestimates the true heritability of this character.<p>The possibility that the calls have evolved as adaptations to prevent hybridization (reinforcement) appears to be unlikely, for reasons like the apparent genetic plasticity of call characters, the observation that females inseminated by heterospecific males produce both viable and fertile offspring, and the fact that these species live ecologically isolated. It seems more probable that the calls obtained their species-specificity as the result of selection and chance, e.g. after founder events. Potentially, sexual selection might also have contributed to the differentiation of at least the male call. In view of the genetic correlation between some male and female call characters found in <em>R. imitans,</em> the possibility that change in the call of one sex might affect that of the other cannot be excluded.<p>The observation that, during distant calling, males are much more selective than females with respect to calls of other species appears to be best explained from the need to to be as efficient as possible in finding a proper conspecific mate. Because <em>Ribautodelphax</em> species are confined to different host plants, the chances of meeting other related species are slim, and selection for precise species recognition is likely to be weak. In order to attract as many as possible males to chose among, it might be sufficient for females to recognize the calls of congenerics, which have basically the same structure. For males precise recognition is likely to be more important. There are usually less mating-receptive females than males present in a population, because females mate only once during their lives, in contrast to males. Tuning to a specific call type would increase the chances of finding as many as possible attractive females, as the fraction of such females (i.e. presumably those with call characteristics close to the population mean), is likely to decrease as the season progresses. In species living syntopically on the same host plant, females might be expected to be at least as selective as males towards heterospecific calls of the other sex, because that would seem to be the most economic and safe way to avoid heterospecific encounters. In two species of the planthopper genus <em>Prokelisia,</em> which share the same hostplant, this indeed seems to be the case.<p>In populations of two <em>Ribautodelphax</em> species, where diploid males and females live associated with triploid gynogenetic females, a peculiar use of the acoustic communication system in a within species context appears to occur. The triploids occasionally arise spontaneously in diploid populations, and need to mate with diploid males, but produce only identical triploid females. Because of their two-fold reproductive advantage, triploids potentially can outcompete the diploid females, which would also lead to their own demise. However, the ratio diploid: triploid females in the field was reported to be stable over time. A model is suggested explaining this stable coexistence by a dynamic 'armsrace' involving the female calls, enabled by the genetic plasticity of the female call, and driven by the selection pressure on males to prefer female calls deviating from the population mean, thereby avoiding mating with the otherwise indistinguishable triploids. This would also explain the peculiar occurrence of several different female call types within and between populations of the species in which such triploids occur.<p>In view of the potential effect of acoustic signals in species recognition, the evolution of the acoustic communication system might be the primary force behind speciation in planthoppers. However, a confounding factor in <em>Ribautodelphax is</em> that, although the species studied live potentially sympatrically, each is confined to one particular host plant species, on which they feed and oviposit and therefore are unlikely to meet related species in the field. Hence, call differentiation could have taken place as the result of isolation after a change to a new host. However, comparative evidence from related genera shows that acoustic differentiation can also occur without a host plant shift. It therefore seems inevitable to conclude that the change of the acoustic communication system in allopatry is indeed the main factor in planthopper speciation. Although speciation will be facilitated by a host plant shift, because it obstructs secondary contact, it appears to be no prerequisite. Species of genera living syntopically on the same host appear to have developed more rigid recognition systems than members of genera which are ecologically or geographically isolated, because interspecific inseminations were reported to be extremely rare or non-existent, even under no-choice conditions. In these species the specific mate recognition system has apparently changed sufficiently in allopatry to enable coexistence with congenerics after secondary contact. The process of speciation is viewed as undirected change of the specific mate recognition system in small isolated populations up to the point where other populations are no longer recognized, which is in accordance with Paterson's recognition species concept, except that the mate recognition system, at least some of its components, appears to be less evolutionary stable than envisaged by that author.
The bionomics of the malaria mosquito Anopheles gambiae sensu lato in Southeast Tanzania : adult size variation and its effect on female fecundity, survival and malaria transmission
Lyimo, E.O.K. - \ 1993
Agricultural University. Promotor(en): Joop van Lenteren; Willem Takken. - S.l. : Lyimo - ISBN 9789054851806 - 142
Culicidae - Chironomidae - Cecidomyiidae - malaria - Anopheles - groei - ecologie - diergedrag - gewoonten - voortplanting - Tanzania - nematocera - growth - ecology - animal behaviour - habits - reproduction
<p>Size of adult mosquitoes is known to affect both population dynamics as well as disease transmission. Studies devoted to this topic have given different results for different species. For example in some mosquito species, large size was found to be associated with high fecundity and longer survival (Steinwascher, 1982; Nasci, 1986a; 1986b; 1987) but in others large size did not result in longer survival (Walker <em>et al</em> ., <em></em> 1987; Landry <em>et al</em> ., <em></em> 1988; Pumpuni & Walker, 1989). Similar data were found for disease transmission. Some results indicated that smaller mosquitoes transmit Japanese Encephalitis, West Nile and La Cross viruses more efficiently than larger mosquitoes (Takahashi, 1976; Baqar <em>et al</em> ., <em></em> 1980; Grimstad & Haramis, 1984), while other results did not show any difference between small and larger mosquitoes in their ability to transmit viral diseases (Kay <em>et al</em> ., <em></em> 1989). With <em>Plasmodium</em> parasites, Ichimori (1989) did not find any relationship between <em>Anopheles stephensi</em> Liston female size and the number of <em>P.</em><em>yoelii nigeriensis</em> oocysts developed, whereas Kitthawee <em>et. al.</em> (1990) showed that large <em>An. dirus</em> Peyton and Harrison developed more <em>P.</em><em>falciparum</em> oocysts than small ones.<p>Variation in mosquito adult size is associated with the type of breeding sites used by a species. Several studies have shown that temporary habitat breeders are more variable in size than permanent habitat breeders (Haramis, 1983; 1985; Fish, 1985; Nasci, 1987). <em>An. gambiae</em> Giles, the subject of this study, breeds preferably in temporary water bodies and is one of the most size variable anophelines in the sub-Saharan region. No work has previously been undertaken to study the effect of adult size on the bionomics of this mosquito, information which could elucidate our understanding of the biology of this important mosquito.<p>The present research study was initiated in order to answer the following general questions: (1) what causes adult size variation in <em>An. gambiae</em> and (2) how does adult size affect important female characteristics such as reproduction, survival duration and malaria transmission. The specific aims of the study were:<br/>- to investigate the effects of temperature and larval density on development and survival of immature <em>An. gambiae</em> and on the size of adults.<br/>- to investigate the effects of adult size on blood feeding and on fecundity.<br/>- to investigate the effects of adult size on survival.<br/>- and to find out the relationship between adult size and malaria parasite infections.<p>In the course of this research, a total of 50,321 female <em>An. gambiae s. 1.</em> were caught using various sampling methods, and 11,097 wings were measured, wing length being an accepted measurement of body size (Christophers, 1960; Haramis, 1983).<p>Factors affecting larval development and adult size were studied in the laboratory as well as in the field. Mosquitoes were reared in the laboratory under various constant temperatures and densities (chapter 2). In the field, larvae were reared at constant densities under natural fluctuating temperatures (chapter 3). Developmental times and survival rates of immatures under different conditions were monitored and the wing length of emerged females compared. Rate of larval development and immature survival as well as size of adults were determined by the interaction between density and temperature.<p>Natural breeding sites were monitored to determine relative densities and survival of immature stages, and the size of emerging adults. Mortality of immatures was very high (on average 95%), caused mainly by pathogens and by predators, as well as weather conditions. Large, semi-permanent breeding sites produced larger sized females than the small temporary puddles (chapter 4). Spatial and temporal differences in adult size were investigated in field populations of <em>An. gambiae s. 1.</em> There was a significant variation in adult size of populations from different localities, and also a seasonal variation in size of mosquitoes collected from the same locality over a two year period, with larger females being caught during the cooler months of the year (chapter 5). Density of female <em>An. gambiae</em> inside houses peaked towards the end of the rainy season in May, which was accompanied by an increase in entomological inoculation rates (the number of infective bites per person per night). Thus, the intensity of malaria transmission was higher towards the end of the rainy season (chapter 6).<p>Effect of adult size on pre-gravidity and on fecundity was examined for blood fed indoor resting mosquitoes and for newly emerged wild females fed in the laboratory. Females which developed eggs after a single blood meal were larger than those which required more than one meal to produce one batch of eggs, and produced more eggs per batch (chapter 7). Survival of adults was investigated by comparing the size of newly emerged females from field collected pupae with that of nulliparous and parous host seeking females (chapter 8). Newly emerged females were significantly smaller than the host seeking females. There was no difference in mean size between nulliparous and parous host seeking mosquitoes. Small- sized females were equally likely to be infected during blood feeding as were large-sized females, but large females produced more oocysts. The proportion of mosquitoes with sporozoites, however, was highest in intermediate sized females (chapter 9). Finally, the effect of adult mosquito size on the overall malaria transmission was examined using a malaria transmission model described by Koella (1991), (chapter 10). The model predicts that mosquito size has little effect on malaria transmission. Possible reasons for this are discussed.<p>The conclusions from these studies are:<br/>(1) Environmental factors, notably the temperature of breeding water, and the density of larvae directly affect the amount of food available to larvae and influence the development and survival of immatures and the size of adult <em>An. gambiae s. 1.</em><br/>(2) Adult size affects time of first reproduction and fecundity of An. <em>gambiae s. I.</em> , <em></em> hence fitness of individual females.<br/>(3) Small sized mosquitoes die early in adult life and do not contribute much to the bionomics, of the species.<br/>(4) Large-sized mosquitoes produced many oocysts, but they did not survive well enough to transmit the parasites (probably due to their heavy oocyst infections).<br/>(5) The effect of adult size on the overall malaria transmission is negligible due to the effects of co-variation in the transmission parameters.
Flight periods of Scirtidae (Coleoptera) based on weekly samples from a malaise trap.
Cuppen, J.G.M. - \ 1993
Entomologische Berichten 53 (1993). - ISSN 0013-8827 - p. 137 - 142.
diergedrag - Coleoptera - ecologie - gewoonten - noord-brabant - animal behaviour - ecology - habits
Filter-feeding in common bream (Abramis brama), white bream (Blicca bjoerkna) and roach (Rutilus rutilus) : structures, functions and ecological significance
Berg, C. van den - \ 1993
Agricultural University. Promotor(en): J.W.M. Osse, co-promotor(en): F.A. Sibbing. - S.l. : Van den Berg - 147
Cyprinidae - karper - ecologie - diergedrag - gewoonten - masticatie - eten - voedingsgedrag - kieuwen - carp - ecology - animal behaviour - habits - mastication - eating - feeding behaviour - gills
<DIV Filter-feeding in common bream <em></DIV><p>In this thesis the retention mechanism of the branchial sieve of three sympatric cyprinid fish species, the common bream <em>(Abramis brama),</em> the white bream <em>(Blicca bjoerkna)</em> and the roach <em>(Rutilus rutilus)</em> , is <em></em> studied. In eutrophic lakes zooplankton is an important food resource and common bream is dominant. Previous research indicated that common bream retains zooplankters in the medial channels on its gill arches. The mesh size of its branchial sieve can be reduced by rotating the lateral rakers into these channels. In this thesis it is shown that of the three species under study the channels of common bream are comparatively the widest. Because of its extra long and pointed lateral gill rakers common bream is most suited to reduce its channels, in the way described above. The retention ability of the fishes was calculated from the decline in density of zooplankton as a function of its size in experimental tanks with filter-feeding fish. These data were compared with the predictions from three retention models. In these predictions the influence of the shape of the zooplankton on retention was taken into account. This aspect was studied in a separate experiment with industrial sieves (with square meshes). The ratio of body width and depth of the zooplankton, proved to be a crucial size parameter for retention. It was concluded from the filter-feeding experiments that the channel model with adjustable mesh size can be applied to common bream. The same model can be applied to white bream, but without the possibility to adjust the mesh size. Roach probably retains zooplankton on its gill slits, according to the saw-tooth model. The presence of abductor muscles for the lateral rakers, which allows them to rotate, is a prerequisite for the application of the reducible-channel model. A detailed micro anatomical study showed that all lateral gill rakers of each gill arch of common bream have such muscles. In white bream and roach, however, these muscles are only present on the lateral gill rakers of the first gill arch. Therefore, the reducible- channel model cannot be applied to <em>these species.</em> During the uptake of zooplankton by suction feeding, the gill arches move along with the expanding head. These gill arch movements affect the relative position of the gill rakers on either side of each gill slit. The gill arch movements were studied in X-ray films of white bream and common bream. A novel, 3D method of analysis was developed to analyze these films quantitatively. The lateral gill rakers of both species proved to be long enough to reach across the gill slit (i.e. into the medial channels), even when the width of the gill slits was maximal. The sideward movement of the lateral gill rakers out of the centre of the medial channels was considerable. The adjustable branchial sieve is not rigid. Due to the mucus encapsulement of trapped particles, the conical shape of the lateral gill rakers and the possibility to rotate them sidewards, the reducible-channel mechanism still functions well. The filter-feeding effectiveness of the three species was quantified in terms of energy. Common bream proved to have a higher energy gain from filter-feeding than its relatives white bream and roach. This difference is probably a crucial factor explaining the dominance of common bream in eutrophic lakes. The present research corroborates the fundamental idea that there is a strong relation between the functional morphology and the ecological niche of a species. Furthermore, small morphological differences between related species (the presence of abductor muscles of the lateral gill rakers) can be used to explain and predict interspecific differences in the exploitation of food sources and the performance in the ecosystem.
Ecologisch profiel van de visdief (Sterna hirundo)
Stienen, E.W.M. ; Brenninkmeijer, A. - \ 1992
Arnhem : IBN (RIN-rapport 92/18) - 128
Sterna - toxicologie - chemicaliën - polycyclische koolwaterstoffen - aromatische koolwaterstoffen - dieren - populatiedichtheid - populatie-ecologie - mortaliteit - populatiegroei - ecologie - diergedrag - gewoonten - biogeografie - fauna - dierziekten - dierpathologie - Europa - milieu - verontreinigende stoffen - verontreiniging - nadelige gevolgen - Nederland - Sterna hirundo - toxicology - chemicals - polycyclic hydrocarbons - aromatic hydrocarbons - animals - population density - population ecology - mortality - population growth - ecology - animal behaviour - habits - biogeography - animal diseases - animal pathology - Europe - environment - pollutants - pollution - adverse effects - Netherlands
Ecologisch profiel van de grote stern (Sterna sandvicensis)
Brenninkmeijer, A. ; Stienen, E.W.M. - \ 1992
Arnhem : DLO-IBN (RIN-rapport 92/17) - 107
diergedrag - dieren - biologische technieken - ecologie - milieu - gewoonten - monitoring - mortaliteit - Nederland - verontreiniging - populatiedichtheid - populatie-ecologie - populatiegroei - Sterna - waterkwaliteit - biologische monitoring - animal behaviour - animals - biological techniques - ecology - environment - habits - mortality - Netherlands - pollution - population density - population ecology - population growth - water quality - biomonitoring
Population ecology and functioning of Enchytraeidae in some arable farming systems
Didden, W. - \ 1991
Agricultural University. Promotor(en): Lijbert Brussaard; L.J. Pons. - S.l. : Didden - 116
Oligochaeta - bodemfauna - veldgewassen - akkerbouw - ecologie - diergedrag - gewoonten - soil fauna - field crops - arable farming - ecology - animal behaviour - habits
<p>The population ecology of Enchytraeidae, and their functioning, were studied in some arable farming systems and in laboratory experiments. The systems studied consisted of a 'conventional' (high input of energy and matter) and several 'integrated' (reduced input of energy and matter) systems. Emphasis was given to population dynamics and the role of Enchytraeidae in nutrient cycling and soil structure evolution.<p>Mean yearly enchytraeid abundance and biomass in the systems studied ranged from 11000 ind/m <sup><font size="-2">2</font></SUP>to 43000 ind/m <sup><font size="-2">2</font></SUP>, and from 0.08 g C/m <sup><font size="-2">2</font></SUP>to 0.42 g C/m <sup><font size="-2">2</font></SUP>, respectively. It was calculated that 0.5-3.7% of the yearly organic carbon input was respired by the enchytraeid populations. Yearly nitrogen flux from the populations (through storage in enchytraeid tissue) ranged from 0.19 to 0.60 g/m <sup><font size="-2">2</font></SUP>.<p>There were no significant differences between the systems studied as regards population dynamical and production ecological parameters. However, vertical distribution of enchytraeid populations differed markedly between the conventional field and the integrated fields, probably related with differences in soil tillage and the resulting distribution of organic fertilizer and plant residues. These differences in vertical distribution may have consequences for the risk of nutrients leaching from the systems.<p>The impact of enchytraeid activity on soil structure evolution was studied in a field experiment with artificial soil cores, in combination with field observations. It was found that enchytraeid activity produced measurable effects on air permeability, pore size distribution, and distribution of aggregate sizes, probably through selective burrowing and transport of organic besides mineral material.<p>Life-history parameters of <em>Enchytraeus buchholzi,</em> the dominant species at the research site, were determined in a laboratory experiment, and predictions based on the laboratory trials were compared with data on population development under more natural conditions. There were significant discrepancies, indicating an influence of the physiological condition of the experimental animals on the length of the life-cycle in this species.
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