Phylodynamics and movement of Phycodnaviruses among aquatic environments

Phycodnaviruses have a significant role in modulating the dynamics of phytoplankton, thereby influencing community structure and succession, nutrient cycles and potentially atmospheric composition because phytoplankton fix about half the carbon dioxide (CO2) on the planet, and some algae release dimethylsulphoniopropionate when lysed by viruses. Despite their ecological importance and widespread distribution, relatively little is known about the evolutionary history, phylogenetic relationships and phylodynamics of the Phycodnaviruses from freshwater environments. Herein we provide novel data on Phycodnaviruses from the largest river system on earth—the Amazon Basin—that were compared with samples from different aquatic systems from several places around the world. Based on phylogenetic inference using DNA polymerase (pol) sequences we show the presence of distinct populations of Phycodnaviridae. Preliminary coarse-grained phylodynamics and phylogeographic inferences revealed a complex dynamics characterized by long-term fluctuations in viral population sizes, with a remarkable worldwide reduction of the effective population around 400 thousand years before the present (KYBP), followed by a recovery near to the present time. Moreover, we present evidence for significant viral gene flow between freshwater environments, but crucially almost none between freshwater and marine environments

Cognitive attraction and online misinformation

© The Author(s) 2019. The spread of online misinformation has gained mainstream attention in recent years. This paper approaches this phenomenon from a cultural evolution and cognitive anthropology perspective, focusing on the idea that some cultural traits can be successful because their content taps into general cognitive preferences. This research involves 260 articles from media outlets included in two authoritative lists of websites known for publishing hoaxes and ‘fake news’, tracking the presence of negative content, threat-related information, presence of sexually related material, elements associated to disgust, minimally counterintuitive elements (and a particular category of them, i.e., violations of essentialist beliefs), and social information, intended as presence of salient social interactions (e.g., gossip, cheating, formation of alliances), and as news about celebrities. The analysis shows that these features are, to a different degree, present in most texts, and thus that general cognitive inclinations may contribute to explain the success of online misinformation. This account can elucidate questions such as whether and why misinformation online is thriving more than accurate information, or the role of ‘fake news’ as a weapon of political propaganda. Online misinformation, while being an umbrella term covering many different phenomena, can be characterised, in this perspective, not as low-quality information that spreads because of the inefficiency of online communication, but as high-quality information that spreads because of its efficiency. The difference is that ‘quality’ is not equated to truthfulness but to psychological appeal.The Netherlands Organisation for Scientific Research (NWO VIDI-grant 016.144312)

Kelp forest size alters microbial community structure and function on Vancouver Island, Canada.

Bacteria are ubiquitous and important components of marine ecosystems, yet the interaction between bacteria and higher trophic levels remain poorly understood. The trophic cascade involving sea otters, urchins, and kelp in the North Pacific is a classic case of altered ecosystem states; however, its impacts on microbial communities are unknown. We investigated the response of microbial communities to variation in kelp abundance between regions with and without sea otter populations along the west coast of Vancouver Island, British Columbia, Canada. We compared bacterial community structure and function between regions with large and small kelp forests, including an subset of the bacterial community that produces alginate lyase, which allows direct utilization of kelp carbon. The abundance and activity of alginate-lyase-producing bacteria were 3.2 and 1.4 times higher, respectively, in the region with large kelp forests, and declined rapidly with increasing distance from kelp. Total bacterial abundance was 2.7 times greater, and bacteria grew faster and experienced more zooplankton grazing and viral-mediated mortality in the presence of large kelp forests. These patterns suggest that larger kelp forests produce more detritus and dissolved organic matter, which stimulate microbial activity. Our results indicate that variation in kelp forest size alters the community structure and productivity of microbes and contributes to the growing evidence that top predators interact with microbes and ecosystem processes through a cascade of indirect effects