13 research outputs found
A public relations identity for the 2010s
New voices are being heard and new questions are being asked within the field of public relations. However, in its present multifaceted state, public relations research is still struggling with recurring questions regarding academic and practical contributions. This position article presents some common starting points for a public relations identity for the 2010s aiming to preserve both consistency and multiplicity. We argue that public relations should be studied as a social activity in its own right and that it must be understood in relation to its societal context. Furthermore, we point to some concepts (trust, legitimacy, understanding and reflection) that are crucial to understanding public relations practice. We also argue that issues of power, behavior, and language have to be dealt with if public relations is to be taken seriously as an academic field. Building on these ideas we make some suggestions for empirical research. Finally, we propose, on a philosophical level, to develop a critical realist framework in order to study public relations scientifically
The Lichen Connections of Black Fungi
Many black meristematic fungi persist on
rock surfaces\u2014hostile and exposed habitats where
high doses of radiation and periods of desiccation
alternate with rain and temperature extremes. To cope
with these extremes, rock-inhabiting black fungi show
phenotypic plasticity and produce melanin as cell wall
pigments. The rather slow growth rate seems to be an
additional prerequisite to oligotrophic conditions. At
least some of these fungi can undergo facultative,
lichen-like associations with photoautotrophs. Certain
genera presenting different lifestyles are phylogenetic
related among the superclass Dothideomyceta. In this
paper, we focus on the genus Lichenothelia, which
includes border-line lichens, that is, associations of
melanised fungi with algae without forming proper
lichen thalli. We provide a first phylogenetic hypothesis
to show that Lichenothelia belongs to the superclass
Dothideomyceta. Further, culture experiments
revealed the presence of co-occurring fungi in Lichenothelia
thalli. These fungi are related to plant
pathogenic fungi (Mycosphaerellaceae) and to other
rock-inhabiting lineages (Teratosphaeriaceae). The
Lichenothelia thallus-forming fungi represent therefore
consortia of different black fungal strains. Our
results suggest a common link between rock-inhabiting
meristematic and lichen-forming lifestyles of
ascomycetous fungi
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Mutational meltdown in primary endosymbionts: selection limits Muller's ratchet
Background
Primary bacterial endosymbionts of insects (p-endosymbionts) are thought to be undergoing the process of Muller's ratchet where they accrue slightly deleterious mutations due to genetic drift in small populations with negligible recombination rates. If this process were to go unchecked over time, theory predicts mutational meltdown and eventual extinction. Although genome degradation is common among p-endosymbionts, we do not observe widespread p-endosymbiont extinction, suggesting that Muller's ratchet may be slowed or even stopped over time. For example, selection may act to slow the effects of Muller's ratchet by removing slightly deleterious mutations before they go to fixation thereby causing a decrease in nucleotide substitutions rates in older p-endosymbiont lineages.
Methodology/Principal Findings
To determine whether selection is slowing the effects of Muller's ratchet, we determined the age of the Candidatus Riesia/sucking louse assemblage and analyzed the nucleotide substitution rates of several p-endosymbiont lineages that differ in the length of time that they have been associated with their insect hosts. We find that Riesia is the youngest p-endosymbiont known to date, and has been associated with its louse hosts for only 13–25 My. Further, it is the fastest evolving p-endosymbiont with substitution rates of 19–34% per 50 My. When comparing Riesia to other insect p-endosymbionts, we find that nucleotide substitution rates decrease dramatically as the age of endosymbiosis increases.
Conclusions/Significance
A decrease in nucleotide substitution rates over time suggests that selection may be limiting the effects of Muller's ratchet by removing individuals with the highest mutational loads and decreasing the rate at which new mutations become fixed. This countering effect of selection could slow the overall rate of endosymbiont extinction