Functional Traits Linked to Pathogen Prevalence in Wild Bee Communities

Reports of pollinator declines have prompted efforts to understand contributing factors and protect vulnerable species. While pathogens can be widespread in bee communities, less is known about factors shaping pathogen prevalence among species. Functional traits are often used to predict susceptibility to stressors, including pathogens, in other species-rich communities. Here, we evaluated the relationship between bee functional traits (body size, phenology, nesting location, sociality, and foraging choice) and prevalence of trypanosomes, neogregarines, and the microsporidian Nosema ceranae in wild bee communities. For the most abundant bee species in our system, Bombus impatiens, we also evaluated the relationship between intra-specific size variation and pathogen prevalence. A trait-based model fit the neogregarine prevalence data better than a taxa-based model, while the taxonomic model provided a better model fit for N. ceranae prevalence, and there was no marked difference between the models for trypanosome prevalence. We found that Augochlorella aurata was more likely to harbor trypanosomes than many other bee taxa. Similarly, we found that bigger bees and those with peak activity later in the season were less likely to harbor trypanosomes, though the effect of size was largely driven by A. aurata. We found no clear intra-specific size patterns for pathogen prevalence in B. impatiens. These results indicate that functional traits are not always better than taxonomic affinity in predicting pathogen prevalence, but can help to explain prevalence depending on the pathogen in species-rich bee communities

A direct comparison of the consequences of plant genotypic and species diversity on communities and ecosystem function

Biodiversity loss is proceeding at an unprecedented rate, yet we lack a thorough understanding of the consequences of losing diversity at different scales. While species diversity is known to impact community and ecosystem processes, genotypic diversity is assumed to have relatively smaller effects. Nonetheless, a few recent studies suggest that genotypic diversity may have quantitatively similar ecological consequences compared to species diversity. Here we show that increasing either genotypic diversity of common evening primrose (Oenothera biennis) or species diversity of old?field plant species resulted in nearly equivalent increases (?17%) in aboveground primary production. The predominant mechanism explaining this effect, niche complementarity, was similar for each type of diversity. Arthropod species richness also increased with both types of plant diversity, but the mechanisms leading to this effect differed: abundance?driven accumulation of arthropod species was important in plant genotypic polycultures, whereas resource specialization was important in plant species polycultures. Thus, similar increases in primary productivity differentially impacted higher trophic levels in response to each type of plant diversity. These results highlight important ecological similarities and differences between genotypic and species diversity and suggest that genotypic diversity may play a larger role in community and ecosystem processes than previously realized.The NSF (DEB- 0950231 to A. A. Agrawal and IGERT small grant in Biogeochemistry and Environmental Biocomplexity to S. H. McArt, S. C. Cook-Patton, and A. L. Parachnowitsch) and USDA-NRI (2006-35302-17431 to J. S. Thaler) supported this wor

Behavioral responses of the endemic shrimp Halocardina rubra (Malacostraca:Atyidae) to an introduced fish, Gambusia affinis (Actinopterygii: Poeciliidae) and implications for the trophic structure of Hawaiian anchialine ponds

In the Hawaiian Islands, intentionally introduced exotic fishes have been linked to changes in native biodiversity and community composition. In 1905, the mosquito fish Gambusia affinis was introduced to control mosquitoes. Subsequently, G. affinis spread throughout the Islands and into coastal anchialine ponds. Previous studies suggest that presence of invasive fishes in anchialine ponds may eliminate native species, including the endemic shrimp Halocaridina rubra. We examined effects of G. affinis on H. rubra populations in anchialine ponds on the Kona-Kohala coast of the island of Hawai/i. In the presence of G. affinis, H. rubra exhibited a diel activity pattern that was not seen in fishless ponds. Shrimp in ponds with fish were active only at night. This pattern was evident in anchialine ponds and in laboratory experiments. In laboratory predation experiments, G. affinis preferentially consumed smaller H. rubra, and in the field the H. rubra collected from invaded sites were larger than those from fishless ponds. Analysis of trophic position using stable isotope analyses showed that feeding of H. rubra was not significantly distinct from that of snails, assumed to feed at trophic level 2.0 on epilithic algae, but G. affinis was slightly omnivorous, feeding at tropic level 2.2. The mosquito fish diet was apparently composed primarily of algae when the defensive behavior of H. rubra made them substantially unavailable as prey. The effect of successful establishment of G. affinis on shrimp behavior has the potential to alter abundance of benthic algae and processing and recycling of nutrients in anchialine pond ecosystems

Pigeons and People: Resource Ecology and Human Dimensions of Urban Wildlife

Urban areas and human populations are growing. Cities provide highly modified habitat for species that can adapt their feeding and other behaviours. The growth of urban landscapes and human populations may result in an increase in human-wildlife conflict. Businesses which prepare and sell food (food establishments) may be more likely to encounter conflict with urban wildlife, which may lead to negative attitudes towards urban wildlife. Negative attitudes towards wildlife could create polarised communities and possibly affect the success of environmental initiatives. This study sought to understand (1) how feral pigeons use urban environments and the resources key to their distribution and congregation; (2) whether feral pigeons are food limited in Wellington City; and (3) how the interactions of owners and managers of food establishments with feral pigeons influence their attitudes to feral pigeons. I used 8 transects through the central City which covered a representative sample of urban habitats, including the central business district, green space, and waterfront to estimate resource selection. Bird capture and banding were used to determine feral pigeon condition at a range of sites across the City and included a mix of high, medium and low anthropogenic fed sites. A written survey of owners and managers of food establishments in Wellington was conducted to evaluate attitudes to feral pigeons (n = 62). Feral pigeon resource selection is mainly influenced by people and where they choose to eat (∆AIC ≤ W = 0.999), such as sites with outdoor seating where people may directly feed feral pigeons. However, once a site has been selected, areas with tertiary vegetation and disposed food (W = 0.324 and W = 0.297) are the most likely to attract larger flocks of feral pigeons (although a number of other variables also influence flock size, such as availability of freshwater). Feral pigeons do not appear to be food limited in Wellington as condition was not significantly different between sites (n=48, body condition, (body mass/tarsus length) Kruskal-Wallis = 2.06, p = 0.36; keel condition, Kruskal-Wallis = 0.7283, p = 0.6948; feather condition Kruskal-Wallis = 2.7943, p = 0.2473). Attitudes of food establishment owners and managers towards feral pigeons are most influenced by how often they see feral pigeons (∆AICc ≤ W = 0:465). Therefore, direct experience rather than knowledge, engagement, action or socio-demographics has the most influence on attitudes of owners and managers of food establishments. These results suggest that feral pigeon populations are largely dependent on the availability of anthropogenic foods. Reducing the food provided by people may limit feral pigeon populations. Reductions in pigeon populations are also likely to change attitudes of business owners and reduce conflict because they will be less likely to encounter pigeons. Limiting feeding and access to food waste is probably the most effective way of managing pigeon populations

A Novel Role for Cathepsin S as a Potential Biomarker in Triple Negative Breast Cancer

Cathepsin S (CTSS) has previously been implicated in a number of cancer types, where it is associated with poor clinical features and outcome. To date, patient outcome in breast cancer has not been examined with respect to this protease. Here, we carried out immunohistochemical (IHC) staining of CTSS using a breast cancer tissue microarray in patients who received adjuvant therapy. We scored CTSS expression in the epithelial and stromal compartments and evaluated the association of CTSS expression with matched clinical outcome data. We observed differences in outcome based on CTSS expression, with stromal-derived CTSS expression correlating with a poor outcome and epithelial CTSS expression associated with an improved outcome. Further subtype characterisation revealed high epithelial CTSS expression in TNBC patients with improved outcome, which remained consistent across two independent TMA cohorts. Further in silico gene expression analysis, using both in-house and publicly available datasets, confirmed these observations and suggested high CTSS expression may also be beneficial to outcome in ER-/HER2+ cancer. Furthermore, high CTSS expression was associated with the BL1 Lehmann subgroup, which is characterised by defects in DNA damage repair pathways and correlates with improved outcome. Finally, analysis of matching IHC analysis reveals an increased M1 (tumour destructive) polarisation in macrophage in patients exhibiting high epithelial CTSS expression. In conclusion, our observations suggest epithelial CTSS expression may be prognostic of improved outcome in TNBC. Improved outcome observed with HER2+ at the gene expression level furthermore suggests CTSS may be prognostic of improved outcome in ER- cancers as a whole. Lastly, from the context of these patients receiving adjuvant therapy and as a result of its association with BL1 subgroup CTSS may be elevated in patients with defects in DNA damage repair pathways, indicating it may be predictive of tumour sensitivity to DNA damaging agents

Eristalis flower flies can be mechanical vectors of the common trypanosome bee parasite, Crithidia bombi

Flowers can be transmission platforms for parasites that impact bee health, yet bees share floral resources with other pollinator taxa, such as flies, that may be hosts or non-host vectors (i.e., mechanical vectors) of parasites. Here, we assessed whether the fecal-orally transmitted gut parasite of bees, Crithidia bombi, can infect Eristalis tenax flower flies. We also investigated the potential for two confirmed solitary bee hosts of C. bombi, Osmia lignaria and Megachile rotundata, as well as two flower fly species, Eristalis arbustorum and E. tenax, to transmit the parasite at flowers. We found that C. bombi did not replicate (i.e., cause an active infection) in E. tenax flies. However, 93% of inoculated flies defecated live C. bombi in their first fecal event, and all contaminated fecal events contained C. bombi at concentrations sufficient to infect bumble bees. Flies and bees defecated inside the corolla (flower) more frequently than other plant locations, and flies defecated at volumes comparable to or greater than bees. Our results demonstrate that Eristalis flower flies are not hosts of C. bombi, but they may be mechanical vectors of this parasite at flowers. Thus, flower flies may amplify or dilute C. bombi in bee communities, though current theoretical work suggests that unless present in large populations, the effects of mechanical vectors will be smaller than hosts

Plant Genotypic Diversity And Its Influence On Arthropod Communities

Genotypic diversity varies markedly among populations of organisms, however the ecological consequences of intraspecific diversity are poorly understood. Here I directly compare the effects of plant species and genotypic diversity on arthropod communities and ecosystem functioning. Through behavioral observations, field experiments, and laboratory assays, I show contrasting mechanisms by which arthropod species richness and evenness are altered by each type of plant diversity. I then show how genotypic diversity of the common evening primrose (Oenothera biennis) reduces herbivory by changing herbivore behavior and physiology, ultimately decreasing consumption efficiency. Finally, I show how O. biennis genotypic diversity attenuates induced plant resistance to the Japanese beetle (Popillia japonica), indirectly increasing plant susceptibility to three native seed predators. As a result, this highly invasive beetle actually increases the fitness of O. biennis by consuming it. Overall, I show that plant genotypic diversity contributes substantially to the structure and functioning of arthropod communities through both direct and indirect mechanisms

R Scripts

A zip file including all R scripts needed to replicate the figures and other results in the paper. It includes a README.TXT file

CorollaLengthData

CSV file of corolla tube length data plotted in Figure 1

Data from: Trait-based modeling of multi-host pathogen transmission: plant-pollinator networks

Epidemiological models for multi-host pathogen systems often classify individuals taxonomically and use species-specific parameter values, but in species-rich communities, that approach may require intractably many parameters. Trait-based epidemiological models offer a potential solution, but have not accounted for within-species trait variation or between-species trait overlap. Here, we propose and study trait-based models with host and vector communities represented as trait distributions without regard to species identity. To illustrate this approach, we develop SIS models for disease spread in plant-pollinator networks with continuous trait distributions. We model trait-dependent contact rates in two common scenarios: nested networks, and specialized plant-pollinator interactions based on trait matching. We find that disease spread in plant-pollinator networks is impacted the most by selective pollinators, universally attractive flowers, and co-specialized plant-pollinator pairs. When extreme pollinator traits are rare, pollinators with common traits are most important for disease spread, whereas when extreme flower traits are rare, flowers with uncommon traits impact disease spread the most. Greater nestedness and specialization both typically promote disease persistence. Given recent pollinator declines caused in part by pathogens, we discuss how trait-based models could inform conservation strategies for wild and managed pollinators. Furthermore, while we have applied our model to pollinators and pathogens, its framework is general and can be transferred to any kind of species interactions, in any community