Interactions between male guppies facilitates the transmission of the mongenean ectoparasite Gyrodactylus turnbulli

In a previous study we found that female guppies shoaled more than males and that there was greater transmission of the ectoparasite Gyrodactylus turnbulli between females. Here, to test for a possible sex bias in parasite transmission, we conducted a similar experiment on single sex shoals of male and female guppies, observing host behaviour before and after the introduction of an infected shoal mate. The initial parasite burden was considerably lower in the present experiment (30 worms versus >100 worms previously) and we used a different stock of ornamental guppies (Green Cobra variety versus a Tuxedo hybrid previously). Contrary to our previous finding, males aggregated significantly more than females. Males performed ‘sigmoid’ displays towards each other, a courtship behaviour that is more generally directed towards females. Due to the high rate of male–male interactions, parasite transmission was 10 times higher between males than between females. Furthermore, shoaling intensity was highest for the most parasitised fish indicating that these infected fish were not avoided by non-parasitised conspecifics. These studies show that certain social behaviours including shoaling and courtship displays, appear to facilitate the transmission of gyrodactylid parasites

Contracts to Communities: A Processual Model of Organizational Virtue

In the face of systemic challenges to corporate legitimacy, scholars and managers alike have been rethinking traditional answers to the question: What does it take to be a good company? We approach this question in two novel ways. We offer a normative answer, grounded in virtue ethics, by introducing a threefold typology of organizational forms. The moral goodness of each form depends on the congruence between its purpose and virtues. But we also offer a positive answer in the form of a processual model which traces corporate goodness to its empirical antecedents and consequences. The model defies a view of organizations as innately good or evil, but rather portrays virtue as the sediment of a value infusion process. We predict that if managers succeed in establishing in their organizations the kind of virtues necessary to support collective moral agency, they can expect to reap gains like enhanced effectiveness and legitimacy. However, when they neglect their moral responsibilities, the result will likely be organizational demise.Stakeholder theory;Corporate performance;Business ethics;Normative theorizing;Organizational goodness;Virtue ethics;Positive theorizing

Het disciplineringsmodel voorbij; over autoriteit en legitimiteit in Corporate Governance

In this inaugural address, it is argued that the field of corporate governance is focused too much on the agency problems between managers and shareholders that result from the separation of ownership and control in public companies. It is argued that the currently dominant managerial disciplining model of corporate governance should be broadened by including: (1) the benefits of centralized decision-making and managerial authority in public firms (and other forms of enterprise organization), (2) the distinct corporate governance problems of other forms of enterprise organization, and (3) issues of legitimacy that that arise when corporate actions unlawfully or disproportionally hurt the interests of third parties outside the firm.aandeelhouders;stakeholders;legitimiteit;bestuursautoriteit;compliance

Assessment of the status, development and diversification of fisheries-dependent communities: Urk Case Study Report

This case study about Urk shows which social and economic challenges this traditional fishing community faces due to its specialization on just a few stocks, the increasing independence of a processing sector no longer reliant on it to supply locally caught fish, and culturally preferences in the way of life and ways of doing things, and the additional hardship of limited TACs, forced decommissioning, low stock prices, and high fixed costs (fuel costs)

Sex-Specific Differences in Shoaling Affect Parasite Transmission in Guppies

Background: Individuals have to trade-off the costs and benefits of group membership during shoaling behaviour. Shoaling can increase the risk of parasite transmission, but this cost has rarely been quantified experimentally. Guppies (Poecilia reticulata) are a model system for behavioural studies, and they are commonly infected by gyrodactylid parasites, notorious fish pathogens that are directly transmitted between guppy hosts. Methodology/Principal Findings:Parasite transmission in single sex shoals of male and female guppies were observed using an experimental infection of Gyrodactylus turnbulli. Parasite transmission was affected by sex-specific differences in host behaviour, and significantly more parasites were transmitted when fish had more frequent and more prolonged contact with each other. Females shoaled significantly more than males and had a four times higher risk to contract an infection. Conclusions/Significance: Intersexual differences in host behaviours such as shoaling are driven by differences in natural and sexual selection experienced by both sexes. Here we show that the potential benefits of an increased shoaling tendency are traded off against increased risks of contracting an infectious parasite in a group-living species

Pace of life, predators and parasites: predator-induced life-history evolution in Trinidadian guppies predicts decrease in parasite tolerance

A common evolutionary response to predation pressure is increased investment in reproduction, ultimately resulting in a fast life history. Theory and comparative studies suggest that short-lived organisms invest less in defence against parasites than those that are longer lived (the pace of life hypothesis). Combining these tenets of evolutionary theory leads to the specific, untested prediction that within species, populations experiencing higher predation pressure invest less in defence against parasites. The Trinidadian guppy, Poecilia reticulata, presents an excellent opportunity to test this prediction: guppy populations in lower courses of rivers experience higher predation pressure, and as a consequence have evolved faster life histories, than those in upper courses. Data from a large-scale field survey showed that fish infected with Gyrodactylus parasites were of a lower body condition (quantified using the scaled mass index) than uninfected fish, but only in lower course populations. Although the evidence we present is correlational, it suggests that upper course guppies sustain lower fitness costs of infection, i.e. are more tolerant, than lower course guppies. The data are therefore consistent with the pace of life hypothesis of parasite defence allocation, and suggest that life-history traits mediate the indirect effect of predators on the parasites of their prey

Much Ado About Nothing: A conceptual critique of CSR

Corporate social responsibility (CSR) as a nominal term clearly resonates with scholars and practitioners alike. As a scientific concept, however, it has often been criticized for its lack of definitional precision and poor measurement. In this paper we review and assess intensional and extensional definitions of the concept, as they have figured in the prior CSR literature. But we also go beyond these traditional review exercises by assessing the role (if any) of the concept in positive theorizing. The upshot of this analysis is that since the CSR concept adds nothing of value to existing frameworks in the field of management and organization, such as the economizing and legitimizing perspectives, it is best to discard it altogether

Evidence for cryptic speciation in directly transmitted Gyrodactylid parasites of Trinidadian guppies

Cryptic species complexes are common among parasites, which tend to have large populations and are subject to rapid evolution. Such complexes may arise through host-parasite co-evolution and/or host switching. For parasites that reproduce directly on their host, there might be increased opportunities for sympatric speciation, either by exploiting different hosts or different micro-habitats within the same host. The genus Gyrodactylus is a specious group of viviparous monogeneans. These ectoparasites transfer between teleosts during social contact and cause significant host mortality. Their impact on the guppy (Poecilia reticulata), an iconic evolutionary and ecological model species, is well established and yet the population genetics and phylogenetics of these parasites remains understudied. Using mtDNA sequencing of the host and its parasites, we provide evidence of cryptic speciation in Gyrodactylus bullatarudis, G. poeciliae and G. turnbulli. For the COII gene, genetic divergence of lineages within each parasite species ranged between 5.7 and 17.2%, which is typical of the divergence observed between described species in this genus. Different lineages of G. turnbulli and G. poeciliae appear geographically isolated, which could imply allopatric speciation. In addition, for G. poeciliae, co-evolution with a different host species cannot be discarded due to its host range. This parasite was originally described on P. caucana, but for the first time here it is also recorded on the guppy. The two cryptic lineages of G. bullatarudis showed considerable geographic overlap. G. bullatarudis has a known wide host range and it can also utilize a killifish (Anablepsoides hartii) as a temporary host. This killifish is capable of migrating overland and it could act as a transmission vector between otherwise isolated populations. Additional genetic markers are needed to confirm the presence of these cryptic Gyrodactylus species complexes, potentially leading to more in-depth genetic, ecological and evolutionary analyses on this multi-host-parasite system

Case Report: man on antiretroviral therapy with painful thighs

A 54 year old man presented with increasing pain in both thighs for three months during a follow up visit at the antiretroviral therapy (ART) clinic of Queen Elizabeth Central Hospital

The effect of blockholders in corporate governance

Unlike the Anglo-Saxon model, whereby ownership of publicly traded companies is typically in the hands of dispersed shareholders, in continental Europe ownership often lies in the hands of what are known as ‘blockholders’. But how does this affect corporate governance, especially when employees, protected by strong labour institutions, are also powerful