120,264 research outputs found
Butterfly fitness under changing food qualities
No full textThe present thesis investigates how different food qualities over the whole life cycle and
across generations affect butterfly development and reproduction, and addresses the following
main questions: (1) What effects have varying nitrogen concentration and different levels of
host plant defence during larval phase on larval and adult performance in butterflies? (2) Can
adult feeding in male and female butterflies compensate for deficiencies acquired during the
larval stage, or even increase butterfly fitness and reproductive success? (3) Does parental
food quality affect the next generation by parental effects (increased provisioning to
offspring, maternal oviposition choice or transgenerational acclimatization)?
With six distinctive experiments, I show that butterfly reproduction and fitness significantly
correlate with food quality and quantity. Thus, there are diverse strategies over the whole
butterfly life cycle to deal with suboptimal food sources in order to maximize reproduction
and fitness. First, during the larval stage, larval feeding duration can be prolonged and relative
consumption rates and/or efficiency of larval nitrogen utilization could be increased to
compensate for low-quality larval host plants. Second, adult nectar diet can compensate for
deficiencies acquired during larval stage and generally enhance reproduction. Furthermore,
female butterflies can use male-derived nuptial gifts for egg production. Third, parents can
increase provisioning to offspring and acclimatize and oviposit progeny to anticipated host
plants by transgenerational acclimatization to increase offspring performance and fitness.
These diverse strategies during larval and adult stage and even trans-generationally to
maximize reproduction and fitness show that butterflies are well adapted to quickly changing
host plant supplies. Furthermore, it shows that the holometabolous life cycle, using different
food sources during larval and adult stage, is a favorable surviving strategy
Erratum
No full textErhardt L, Moller R, Puig JC. 2007. Comprehensive cardiovascular risk management – what does it mean in practice? Vasc Health Risk Manag, 3:587–603.The way that data from the REACH study are presented in Figure 2 may lead to some confusion when viewed in isolation or without prior knowledge of this study. ..
Interview with Rhoda Erhardt, MS, OTR/L, FAOTA
No full textThis life history is one of 29 life history interviews which are a part of a larger project, Life Histories of Individuals Who Have Been Influential in Developing Occupational Therapy in North Dakota and Wyoming. The purpose of the project is to gather information about the history and evolution of OT practice in North Dakota and Wyoming through life histories of individuals who have been influential in developing OT in these two states. It is anticipated that the life history process will be a powerful way to gather this information. By using a life history approach, this study focused on the participant, Rhoda Erhardt’s, involvement in the evolution of OT practice. This study intends to provide current and future generations of occupational therapists with a view of the history and how OT practice has evolved from its inception to current practice in North Dakota and Wyoming. Rhoda Erhardt is a well known practitioner in the state of North Dakota and has achieved many accomplishments throughout the years. In order to gather information about her experiences as an occupational therapist, the researchers conducted an over the phone interview with Rhoda
[half length portrait of Antoinette Erhardt Voight].
No full textPhoto Div C.3 .Pease papers.9. Half length portrait of Antoinette Erhardt Voight.; Handwritten on verso, "Antoinette Erhardt Voight."; Studio portraits of individual men, women and children, 2 group portraits of women, and 1 photographic reproduction of a drawing.; Subjects include: Calvin Pease; Martha H. Pease; Matilda H. Pease; Sarah W. Pease; Jane Hunt Pease; Mary Wait; Jane H. Wheeler; Antoinette Erhardt Voigt; Mary M. Hickock; and Nellie Adams.; Photographers include: Alexander Gardner (Washington, D.C.); F. Forshew (Hudson, N.Y.); S.O. Hersey (Montpelier, Vt.); J.B. Roberts & Co. (Rochester, N.Y.); L.A. Atwood (Burlington, Vt.); J.H. Kent (Rochester, N.Y.); R.H. Furman (Rochester, N.Y.); Frederick R. Menns (Burlington, Vt.); W. Stockford (Montreal); C.L. Howe (Brattleboro, Vt.); Powelson (Rochester, N.Y.); H.L. Bixby ( Burlington, Vt.); Pach Bros. (N.Y.); Carey & Parker (Burlington, Vt.
The invasive plant Impatiens glandulifera affects mycorrhizal fungi, plant and invertebrate diversity in deciduous forests
No full textNon-native plant species have the potential to affect an ecosystem by changing species diversity, community structure and interactions among organisms. It is therefore important to understand potential mechanisms that contribute to the success of invasive plants. In the context of my PhD thesis, I examined the effect of the invasive annual herb I. glandulifera on mycorrhizal, plant and invertebrate diversity in a deciduous forest near Basel (Switzerland). I also studied the potential mechanism that could contribute to the success of I. glandulifera. A controlled field experiment was set up in three forest areas that were affected to a different extend (little, moderatly, high) by a former wind storm. In each area, three different plot types were installed: plots invaded by I. glandulifera, plots from which the invasive plants had been manually removed and plots which were no yet colonized by the invasive plant. The results of my thesis demonstrate that I. glandulifera affects above and as well as belowground organisms and has the potential to change soil conditions.
Aboveground gastropod richness and abundance were found to be higher in invaded plots than in control plots. The presence of I. glandulifera also altered the composition of gastropod species. Belowground fewer types of ectomycorrhiza were found on root systems of F. sylvatica saplings. Moreover, in plots with I. glandulifera the composition of ectomycorrhiza morphotypes was shifted. Considering mycorrhizal colonisation on fine roots saplings of both tree species, the presence of the invasive plant resulted in a reduction of ectomycorrhizal colonisation of F. sylvatica saplings and of arbuscular mycorrhiza colonisation on A. pseudoplatanus. Thus, disruption of mycorrhizal symbiosis probably led to a lower biomass and survival rate in saplings of both species grown in invaded plots. Additional results showed that soil moisture, soil pH, available phosphorus and microbial activity were increased in invaded plots.
Increased gastropods abundance and richness could be explained by higher soil moistures and damped soil temperature in invaded plots. However, measured changes in soil conditions did not affect mycorrhizal colonisation and performance of both sapling species. Therefore allelopatic effects of I. glandulifera on mycorrhizal symbioses were also examined. Allelopatic compounds are known to contribute to the spread of some invasive plant species and can disrupt mycorrhizal symbiosis. I identified the allelopathic compound 2-methoxy-1,4-naphtoquinone (2-MNQ) in plant organs of I. glandulifera, in soil of its proximity and in rain water rinsed from its leaves. Specific bioassays using shoot and root extracts of I. glandulifera as well as synthetic 2-MNQ revealed strong inhibitory effects on mycelium growth of ectomycorrhiza fungi and on the germination of native forest herbs. This finding indicates that the release of 2-MNQ may contribute to the invasion success of I. glandulifera.
Health, function and diversity of forest ecosystems are closely linked to the abundance and richness of mycorrhizal fungi. This study demonstrates that the spread I. glandulifera into deciduous forest ecosystem resulted in lower mycorrhizal colonisation of saplings. Thus, forest regeneration might be strongly affected by I. glandulifera. Moreover, changes in soil chemistry and soil conditions induced by I. glandulifera caused shifts in above- and belowground communities. Therefore ecosystem services and functions of forest habitats can be affected. Removal or stopping the preceding spread of I. glandulifera may be an investment for the conservation of native species and may prevent potential losses in timber production
Dynamics in team-based knowledge work: understanding processes and media use
No full textTeams are fundamental mechanisms to create and mobilize knowledge in the workplace. Yet, our understanding of the internal processes that govern the manner in which teams create and mobilize knowledge remains limited. Drawing on 102 interviews (over 65 hours of recorded data) and archival data such as team observations, over 400 emails between team members, and documents in six team projects in the USA and Sweden from pharmaceutical, insurance and engineering companies, I build a grounded theory of team-based knowledge work. The theory delineates three key knowledge processes that constitute the notion of team-based knowledge work – knowledge sharing, knowledge creation and team learning. This theoretical framing is then further explored in the context of task complexity, distributed knowledge, interdependence, media use and political dynamics in teams. Theoretical and practical implications are addressed.Ph.D.Includes bibliographical references (p. 173-193)by Niclas L. Erhard
Using ecological and field survey data to establish a national list of the wild bee pollinators of crops
No full textMM was funded by grant INIA-RTA2013-00139-C03-01 (MINECO and FEDER)Hutchinson, L.A., Oliver, T.H., Breeze, T.D., Bailes, E.J., Brünjes, L., Campbell, A.J., Erhardt, A., de Groot, G.A., Földesi, R., García, D., Goulson, D., Hainaut, H., Hambäck, P.A., Holzschuh, A., Jauker, F., Klatt, B.K., Klein, A.-M., Kleijn, D., Kovács-Hostyánszki, A., Krimmer, E., McKerchar, M., Miñarro, M., Phillips, B.B., Potts, S.G., Pufal, G., Radzevičiūtė, R., Roberts, S.P.M., Samnegård, U., Schulze, J., Shaw, R.F., Tscharntke, T., Vereecken, N.J., Westbury, D.B., Westphal, C., Wietzke, A., Woodcock, B.A., Garratt, M.P.D
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Traditional versus sprinkler irrigation of mountain hay meadows in the Valais : consequences for biodiversity
No full textSemi-natural grasslands including hay meadows belong to the most species-rich habitats in central Europe and are therefore of high conservation value. The high biodiversity of these grasslands has been maintained for many centuries through the regular disturbance by traditional management practices. In the Valais, an arid mountain region of Switzerland, traditional management of hay meadows includes irrigation by open water channels. In the past decades, however, the traditional irrigation technique was increasingly replaced by more efficient sprinkler-irrigation systems or irrigation was stopped on marginal and poorly accessible areas. Within the scope of this thesis, four studies were conducted to investigate different aspects of these changes in meadow irrigation.
The aim of the first study was to examine whether land-use abandonment resulting from the cessation of irrigation influenced the biodiversity of hay meadows in the Valais. For this purpose, plant and gastropod surveys were conducted in three serial stages of succession (hay meadows, early abandoned meadows and young forests). Meadow abandonment resulted in an increase in gastropod species richness and a loss of plant and gastropod species characteristic for open grassland habitats. Furthermore, functional traits of plants (plant height, the start of seed shedding and the type of reproduction) and gastropods (shell size) were affected by abandonment.
Traditional meadow irrigation is assumed to distribute the water more heterogeneously than sprinkler irrigation, which might affect meadow biodiversity as well as the distribution of plants in a small scale. The aim of the second study was to examine whether the change from traditional to sprinkler irrigation affected the local biodiversity (plants and gastropods) of hay meadows in the Valais. A high plant species richness was found in the hay meadows investigated. The diversity and composition of plant and gastropod species did not differ between traditionally and sprinkler-irrigated meadows. However, the installation of sprinkler systems resulted in an increase in the grass-to-forb ratio and affected the leaf distribution and the start of seed shedding in plants.
The third study aimed to investigate whether the change in irrigation technique affected the small-scale distribution of plants and soil characteristics in these hay meadows. Three sampling plots consisting of 13 subplots of increasing size were installed in traditionally and sprinkler-irrigated meadows to assess plant species richness and soil characteristics within subplots. The type of irrigation technique did not affect the shape of the plant species-area relationship. Furthermore, spatial autocorrelation in the soil characteristics examined was low and their small-scale distributions were mostly not influenced by the irrigation technique. These findings indicate a pronounced small-scale heterogeneity in the distribution of plant species and soil characteristics in the hay meadows investigated. Therefore, as practiced in our study areas, the distribution of water by sprinklers might be less homogenous than commonly assumed.
The abandonment of traditional management practices of semi-natural grasslands is suggested to result in a reduced landscape heterogeneity, which in turn might contribute to the loss of local plant diversity. The fourth study aimed to investigate whether the change from traditional to sprinkler irrigation resulted in alterations in the surrounding landscape of species-rich hay meadows. Furthermore, we asked if plant diversity of differently irrigated meadows is influenced by landscape composition and the heterogeneity of the surrounding landscape. Landscape composition was more diverse for traditionally than for sprinkler-irrigated meadows, but did not differ prior to the installation of sprinklers. A diverse small-scale landscape composition in the close surroundings of hay meadows had a positive effect on the number of generalists but not on total plant species richness or the number of specialists. Finally, sprinkler-irrigated meadows had an increased number of generalist plant species.
The findings of this thesis suggest that the installation of sprinklers did not affect the local species richness of plants and gastropods in the hay meadows investigated. Nevertheless, the change in irrigation technique influenced functional aspects of plant diversity (plant traits, grass-to-forb ratio and generalist species). Furthermore, the installation of sprinklers was associated with a homogenization of the landscape, which may eventually result in an intensification of land use. For the conservation of the biodiversity of these hay meadows it is recommended to maintain the relatively extensive irrigation and management practices
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