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Open Access Publications from the University of California

Recent Work

Multicampus Research Programs and Initiatives (MRPI) fund innovative multicampus or systemwide research collaborations that go beyond individual PI-driven projects to benefit the UC research enterprise, strengthen UC’s position as a leading public research university, launch pioneering research in thematic, multidisciplinary or inter-disciplinary areas, and benefit California and its people. The program is open to all fields of research and scholarship.

Cover page of Non-native honey bees disproportionately dominate the most abundant floral resources in a biodiversity hotspot

Non-native honey bees disproportionately dominate the most abundant floral resources in a biodiversity hotspot

(2019)

Most plant-pollinator mutualisms are generalized. As such, they are susceptible to perturbation by abundant, generalist, non-native pollinators such as the western honey bee (Apis mellifera), which can reach high abundances and visit flowers of many plant species in their expansive introduced range. Despite the prevalence of non-native honey bees, their effects on pollination mutualisms in natural ecosystems remain incompletely understood. Here we contrast community-level patterns of floral visitation by honey bees with that of the diverse native pollinator fauna of southern California, USA. We show that the number of honey bees visiting plant species increases much more rapidly with flower abundance than does that of non-honey bee insects, such that the percentage of all visitors represented by honey bees increases with flower abundance. Thus, honey bees could disproportionately impact the most abundantly blooming plant species and the large numbers of both specialised and generalised pollinator species that they sustain. Honey bees may preferentially exploit high-abundance floral resources because of their ability to recruit nestmates; these foraging patterns may cause native insect species to forage on lower-abundance resources to avoid competition. Our results illustrate the importance of understanding foraging patterns of introduced pollinators in order to reveal their ecological impacts.

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Cover page of Myeloid differentiation factor 88 (MyD88) and IL-1R1 signaling contribute to resistance to Coccidioides immitis.

Myeloid differentiation factor 88 (MyD88) and IL-1R1 signaling contribute to resistance to Coccidioides immitis.

(2018)

Rodents are a natural host for the dimorphic pathogenic fungi Coccidioides immitis and posadasii, and mice are a good model for human infection. Humans and rodents both express Dectin-1 and TLR2 on myeloid cells and those receptors collaborate to maximize the cytokine/chemokine responses to spherules (the tissue form of the fungi), and to formalin killed spherules (FKS). We showed that Dectin-1 is necessary for resistance to pulmonary coccidioidomycosis, but the importance of TLR2 in vivo is uncertain. MyD88 is the adapter protein for TLR2 and 4, and IL-1R1 and IL-18R1. MyD88/TRIF -/-and MyD88 -/- mice were equally susceptible to C. immitis infection, compared to C57BL/6 (B6) controls. Of the four surface receptors, only IL-1R1 was required for resistance to C. immitis, partially explaining the susceptibility of MyD88 -/- mice. We also found that FKS stimulated production of IL-1Ra by BMDC, independent of MyD88 and Dectin-1. There also was a very high concentration of IL-1Ra in the lungs of infected B6 mice, supporting the potential importance of this regulatory IL-1 family protein in the largely ineffective response of B6 mice to coccidioidomycosis. These results suggest that IL-1R1 signaling is important for defense against C. immitis infection.

Cover page of How Transaction Costs Obstruct Collective Action: The Case of Califoria's Groundwater

How Transaction Costs Obstruct Collective Action: The Case of Califoria's Groundwater

(2018)

Collective action to remedy the losses of open access to common-pool resources often is late and incomplete, extending rent dissipation. Examples include persistent over-exploitation of oil fields and ocean fisheries, despite general agreement that production constraints are needed. Contracting costs encountered in assigning property rights are an explanation, but analysis of their role is limited by a lack of systematic data. We examine governance institutions in California’s 445 groundwater basins using a new dataset to identify factors that influence the adoption of extraction controls. In 309 basins, institutions allow unconstrained pumping, while an additional 105 basins have weak management plans. Twenty of these basins are severely overdrafted. Meanwhile, users in 31 basins have defined groundwater property rights, the most complete solution. We document the critical role of the transaction costs associated with contracting in explaining this variation in responses. This research adds to the literatures on open access, transaction costs, bargaining, and property rights.