54 research outputs found
Ethics beyond the code of conduct - understanding the ethical dilemmas of entrepreneurs
Entrepreneurs choose a particular way of life with the dual aim of maximising profit and gaining a sense of self-satisfaction. In these endeavours, entrepreneurs typically live with the threat of competition and the risk of business failure, while attempting to do their best within the limitations of their resources. This qualitative study first examines existing theories of ethics and ways of applying business ethics and thereafter investigates entrepreneurs' actual experiences by means of in-depth interviews and the use of phenomenology. It finds that entrepreneurs are not guided by any specific code of conduct, and must decide for themselves what is right. It describes the entrepreneurial business ethic, some of the types of dilemmas that they experience and the methods that they have developed to deal with the dilemmas
Multi-site interaction turnover in flea–mammal networks from four continents: Application of zeta diversity concept and multi-site generalised dissimilarity modelling
We studied patterns of changes in host–flea interactions measured as total turnover (TT) which can be partitioned into components, namely species turnover (ST), interaction rewiring (RW), and mixed turnover (MX) in networks from Europe, Asia, Africa, and South America, applying a multi-site interaction turnover metric. We also searched for environmental drivers of TT and its components. We asked whether (a) different components contribute differently to TT in rare versus common interactions (in terms of frequency of interaction occurrence); (b) relative roles of turnover components for rare and common interactions differ between continents; and (c) the environmental drivers of interaction turnover differ between turnover components, rare and common interactions, and/or continental networks. Between-network dissimilarity of interactions increased with an increase in the number of compared networks. Pure ST contributed the most to the turnover of rare interactions, whereas the turnover of common interactions was predominated by MX. The effects of environmental factors, interaction richness, and spatial distance on TT and its components differed between continental networks, turnover components, and rare versus common interactions. Climate and vegetation exerted the strongest effects on (a) ST for rare (except Asia) and, to a lesser degree, common (South America) interactions, (b) RW for both rare and common interactions in Europe/Asia, and (c) MX for both rare and common interactions (except Africa). Interaction richness and spatial distance mainly influenced ST. We conclude that the patterns of interaction turnover and its components were geographically invariant and did not depend on the identity of the interactors, whereas the drivers of the turnover differed between continental networks because of species-specific responses to the environment.Fil: Krasnov, Boris R.. Ben Gurion University of the Negev; IsraelFil: Khokhlova, Irina S.. Ben Gurion University of the Negev; IsraelFil: Kiefer, Mathias S.. Ludwig Maximilians Universitat; AlemaniaFil: Kiefer, Daniel. Ludwig Maximilians Universitat; AlemaniaFil: Lareschi, Marcela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Estudios Parasitológicos y de Vectores. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Centro de Estudios Parasitológicos y de Vectores; ArgentinaFil: Matthee, Sonja. Stellenbosch University; SudáfricaFil: Sánchez, Juliana Patricia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro de Investigaciones y Transferencia del Noroeste de la Provincia de Buenos Aires. Universidad Nacional del Noroeste de la Provincia de Buenos Aires. Centro de Investigaciones y Transferencia del Noroeste de la Provincia de Buenos Aires; ArgentinaFil: Shenbrot, Georgy I.. Ben Gurion University of the Negev; IsraelFil: Stanko, Michal. Slovak Academy of Sciences. Institute of Botany; EslovaquiaFil: van der Mescht, Luther. Stellenbosch University; Sudáfric
Latitudinal distributions of the species richness, phylogenetic diversity, and functional diversity of fleas and their small mammalian hosts in four geographic quadrants
We studied latitudinal patterns in the species richness (SR), the phylogenetic diversity (PD), and the functional diversity (FD) of fleas and their mammalian hosts. We asked whether these patterns in either fleas, hosts, or both 1) conform to a classical latitudinal gradient; 2) vary geographically; and 3) differ between fleas and hosts. We also asked whether the patterns of PD and FD follow those of SR. We collected data on the latitudinal distribution of 1022 flea and 900 mammal species from literature sources and calculated the SR, PD, and FD of both groups in 1° latitude bands. Then, we used broken-stick regression models to analyse separately the latitudinal variation of 1) each diversity facet and 2) fleas and hosts in each geographic quadrant. The classical latitudinal gradient pattern was not found in either fleas or hosts across any facet of diversity or geographic quadrant, except for the PD of fleas in the southeastern quadrant and the FD of hosts in the southwestern quadrant. Latitudinal patterns of the SR, PD and FD of fleas and hosts differed substantially between geographic quadrants. Furthermore, the latitudinal distributions of flea and host SR were similar in three of four quadrants (except the northeastern quadrant), whereas the latitudinal distributions of flea and host PD were similar in the southwestern quadrant only. No similarity in flea versus host FD was revealed. The latitudinal patterns of flea and host PD and FD mostly did not follow those of their SR. We conclude that latitudinal gradients of species richness and phylogenetic and functional diversity appeared not to be universal phenomena. Instead, the latitudinal distributions of these diversity facets represent an interplay of ecological (current and past) and historical processes. For parasites, the processes acting on hosts add another layer of complexity underlying their latitudinal diversity patterns.Fil: Krasnov, Boris R.. Ben Gurion University of the Negev; IsraelFil: Grabovsky, Vasily I.. Ben Gurion University of the Negev; IsraelFil: Khokhlova, Irina S.. Ben Gurion University of the Negev; IsraelFil: Lopez Berrizbeitia, Maria Fernanda. Fundación Miguel Lillo; Argentina. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel Lillo. Programa de Investigación de Biodiversidad Argentina; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán; ArgentinaFil: Matthee, Sonja. No especifíca;Fil: Roll, Uri. Ben Gurion University of the Negev; IsraelFil: Sánchez, Juliana Patricia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro de Investigaciones y Transferencia del Noroeste de la Provincia de Buenos Aires. Universidad Nacional del Noroeste de la Provincia de Buenos Aires. Centro de Investigaciones y Transferencia del Noroeste de la Provincia de Buenos Aires; ArgentinaFil: Shenbrot, Georgy I.. Ben Gurion University of the Negev; IsraelFil: van der Mescht, Luther. No especifíca
Trialling meta-research in comparative cognition: claims and statistical inference in animal physical cognition
Scientific disciplines face concerns about replicability and statistical inference, and these concerns are also relevant in animal cognition research. This paper presents a first attempt to assess how researchers make and publish claims about animal physical cognition, and the statistical inferences they use to support them. We surveyed 116 published experiments from 63 papers on physical cognition, covering 43 different species. The most common tasks in our sample were trap-tube tasks (14 papers), other tool use tasks (13 papers), means-end understanding and string-pulling tasks (11 papers), object choice and object permanence tasks (9 papers) and access tasks (5 papers). This sample is not representative of the full scope of physical cognition research; however, it does provide data on the types of statistical design and publication decisions researchers have adopted. Across the 116 experiments, the median sample size was 7. Depending on the definitions we used, we estimated that between 44% and 59% of our sample of papers made positive claims about animals’ physical cognitive abilities, between 24% and 46% made inconclusive claims, and between 10% and 17% made negative claims. Several failures of animals to pass physical cognition tasks were reported. Although our measures had low inter-observer reliability, these findings show that negative results can and have been published in the field. However, publication bias is still present, and consistent with this, we observed a drop in the frequency of p-values above .05. This suggests that some non-significant results have not been published. More promisingly, we found that researchers are likely making many correct statistical inferences at the individual-level. The strength of evidence of statistical effects at the group-level was weaker, and its p-value distribution was consistent with some effect sizes being overestimated. Studies such as ours can form part of a wider investigation into statistical reliability in comparative cognition. However, future work should focus on developing the validity and reliability of the measurements they use, and we offer some starting points
Comparative phylogeography of parasitic Laelaps mites contribute new insights into the specialist-generalist variation hypothesis (SGVH)
BACKGROUND: The specialist-generalist variation hypothesis (SGVH) in parasites suggests that, due to patchiness in
habitat (host availability), specialist species will show more subdivided population structure when compared to
generalist species. In addition, since specialist species are more prone to local stochastic extinction events with their
hosts, they will show lower levels of intraspecific genetic diversity when compared to more generalist.
RESULTS: To test the wider applicability of the SGVH we compared 337 cytochrome oxidase I mitochondrial DNA and
268 nuclear tropomyosin DNA sequenced fragments derived from two co-distributed Laelaps mite species and
compared the data to 294 COI mtDNA sequences derived from the respective hosts Rhabdomys dilectus, R. bechuanae,
Mastomys coucha and M. natalensis. In support of the SGVH, the generalist L. muricola was characterized by a high
mtDNA haplotypic diversity of 0.97 (±0.00) and a low level of population differentiation (mtDNA Fst= 0.56, p < 0.05;
nuDNA Fst = 0.33, P < 0.05) while the specialist L. giganteus was overall characterized by a lower haplotypic diversity of
0.77 (±0.03) and comparatively higher levels of population differentiation (mtDNA Fst = 0.87, P < 0.05; nuDNA Fst = 0.48,
P < 0.05). When the two specialist L. giganteus lineages, which occur on two different Rhabdomys species, are
respectively compared to the generalist parasite, L. muricola, the SGVH is not fully supported. One of the specialist L.
giganteus species occurring on R. dilectus shows similar low levels of population differentiation (mtDNA Fst= 0.53, P < 0.
05; nuDNA Fst= 0.12, P < 0.05) than that found for the generalist L. muricola. This finding can be correlated to
differences in host dispersal: R. bechuanae populations are characterized by a differentiated mtDNA Fst of 0.79 (P < 0.05)
while R. dilectus populations are less structured with a mtDNA Fst= 0.18 (P < 0.05).
CONCLUSION: These findings suggest that in ectoparasites, host specificity and the vagility of the host are both
important drivers for parasite dispersal. It is proposed that the SGHV hypothesis should also incorporate reference to
host dispersal since in our case only the specialist species who occur on less mobile hosts showed more subdivided
population structure when compared to generalist species
Remnant fragments within an agricultural matrix enhance conditions for a rodent host and its fleas
Please help populate SUNScholar with the full text of SU research output. Also - should you need this item urgently, please send us the details and we will try to get hold of the full text as quick possible. E-mail to [email protected]. Thank you.Journal Articles (subsidised)AgriwetenskappeBewaringsekologie en Entomologi
Flea diversity on small carnivores in the Northern Cape Province, South Africa
Small carnivores are parasitized by various ectoparasites that include fleas (Siphonaptera). To date few parasite studies in South Africa, and especially the Northern Cape, have focused on fleas, while those that have are biased by small sample sizes. In an attempt to address the paucity of information fleas were collected from five small carnivore species trapped at Loxton and Kimberley in the Northern Cape Province, South Africa. The aim of the study was to contribute to current data on the flea diversity found on various small carnivore species. Small carnivores were trapped and while anesthetized the fleas were manually removed from the fur of the animals. In total 48 small carnivores were trapped of which 30 harboured fleas. Of the five flea species that were recorded the most numerous and prevalent was Echidnophaga gallinacea followed by Ctenocephalides connatus and Ctenocephalides damarensis. Fleas were more numerous and prevalent on the small-spotted cat, Felis nigripes, followed by the yellow mongoose, Cynictispenicillata. The flea community on the small carnivores consisted of fleas that prefer carnivores as principal hosts and also fleas that prefer rodents. The latter maybe acquired through predation on rodents.Key words: Siphonaptera, fleas, small carnivores, South Africa
- …