Abstract. Plants engage in diverse and intimate interactions with unrelated taxa. For example, aboveground floral visitors provide pollination services, while belowground arbuscular mycorrhizal fungi (AMF) enhance nutrient capture. Traditionally in ecology, these processes were studied in isolation, reinforcing the prevailing assumption that these above-and belowground processes were also functionally distinct. More recently, there has been a growing realization that the soil surface is not a barrier to many ecological interactions, particularly those involving plants (who live simultaneously above and below ground). Because of the potentially large impact that mycorrhizae and floral visitors can have on plant performance and community dynamics, we designed an experiment to test whether these multi-species mutualisms were interdependent under field conditions. Using benomyl, a widely used fungicide, we suppressed AMF in a native grassland, measuring plant, fungal, and floralvisitor responses after three years of fungal suppression. AMF suppression caused a shift in the community of floral visitors from large-bodied bees to small-bodied bees and flies, and reduced the total number of floral visits per flowering stem 67% across the 23 flowering species found in the plots. Fungal suppression has species-specific effects on floral visits for the six most common flowering plants in this experiment. Exploratory analyses suggest these results were due to changes in floral-visitor behavior due to altered patch-level floral display, rather than through direct effects of AMF suppression on floral morphology. Our findings indicate that AMF are an important, and overlooked, driver of floral-visitor community structure with the potential to affect pollination services. These results support the growing body of research indicating that interactions among ecological interactions can be of meaningful effect size under natural field conditions and may influence individual performance, population dynamics, and community structure.

When political elites receive unfavorable news coverage, a common strategy is to attack the source. Past research suggests that attacks on the news media increase perceptions of media bias, but it remains unclear how this occurs. Using two experiments, the author examines how attacks on the news media increase perceptions of bias. For the experiments, all participants read news articles about elected officials, but some read an attack on the source. The author also manipulated the direction of the attack (liberal or conservative bias) and its placement before or after the article. The results suggest that elite attacks increase perceptions of bias in the news source, and this occurs even when the attack is read following the article. In addition, attacks were effective when they came from politicians in both parties, suggesting that Republicans and Democrats are able to influence perceptions of bias. In conclusion, the author argues that elite attacks are likely to benefit the attackers but weaken democratic accountability.

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In this article, we examine both the content and effects of opinion shows during the 2008 presidential election. First, a content analysis shows that opinion shows devote most of their attention to attacking the opposition candidate, rather than praising the like-minded candidate. Second, analyses of panel data show that exposure to opinion shows made viewers less (more) favorable toward the opposition (like-minded) candidate. Finally, we use overtime analyses to show that coverage of the opposition candidate affects attitudes toward both candidates, whereas coverage of the like-minded candidate has negligible effects on attitudes toward either candidate.