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This Week in PNAS: Apr 5, 2016

In the early, online edition of the Proceedings of the National Academy of Sciences, researchers from the UK, Saudi Arabia, the United Arab Emirates, and Israel report on genetic features found in the coral symbiotic algae Symbiodinium thermophilum in the spectacularly saline, witheringly warm waters of the Persian/Arabian Gulf — an environment that has formed in fewer than 6,000 years. When the team used targeted sequencing to compare the genetic diversity of S. thermophilum at sites in the Gulf with those found at locations thousands of miles away along the Red Sea or in the Gulf of Oman, it saw pronounced genetic diversity in a phylogenetic subset of S. thermophilum that stretched back to ancient ancestors of the algal species.

Also in PNAS, an Austrian team uses several mathematical simulations of systems from weakly selective to selection-heavy to explore the ways in which genetic interactions such as epistasis may affect long-term response to directional selection. In situations with genetic drift, for example, the researchers found evidence for relatively modest effects of genetic architecture on long-term evolutionary responses. In contrast, their models of systems under strong selection suggests that genotype-phenotype interactions are more likely to affect selection response.  

Finally, researchers from the University of California at Davis and elsewhere describe results from a retrospective study of Nosema bombi fungal pathogens in wild North American bumble bee populations. Using PCR-based N. bombi DNA detection, the team searched for the presence of the pathogen in historical samples from five Bombus bumble bee species collected between the late 1970s and 2011. The search pointed to a rise in N. bombi prevalence in the 1990s, following infections in commercial colonies. However, the pathogen's genetic features did not seem to shift significantly before or after N. bombi became more widespread in the wild. Our sister publication GenomeWeb Daily News has more on the study here.

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