The extent to which the biodiversity and community composition of ecosystems affect their functions is an issue that grows ever more compelling as human impacts on ecosystems increase. We present evidence that supports a novel function of vertebrate biodiversity, the buffering of human risk of exposure to Lymedisease-bearing ticks. We tested the Dilution Effect model, which predicts that high species diversity in the community of tick hosts reduces vector infection prevalence by diluting the effects of the most competent disease reservoir, the ubiquitous white-footed mouse (Peromyscus leucopus). As habitats are degraded by fragmentation or other anthropogenic forces, some members of the host community disappear. Thus, species-poor communities tend to have mice, but few other hosts, whereas species-rich communities have mice, plus many other potential hosts. We demonstrate that the most common nonmouse hosts are relatively poor reservoirs for the Lyme spirochete and should reduce the prevalence of the disease by feeding, but rarely infecting, ticks. By accounting for nearly every host species' contribution to the number of larval ticks fed and infected, we show that as new host species are added to a depauperate community, the nymphal infection prevalence, a key risk factor, declines. We identify important ''dilution hosts'' (e.g., squirrels), characterized by high tick burdens, low reservoir competence, and high population density, as well as ''rescue hosts'' (e.g., shrews), which are capable of maintaining high disease risk when mouse density is low. Our study suggests that the preservation of vertebrate biodiversity and community composition can reduce the incidence of Lyme disease.

Vectors of infectious diseases are generally thought to be regulated by abiotic conditions such as climate or the availability of specific hosts or habitats. In this study we tested whether blacklegged ticks, the vectors of Lyme disease, granulocytic anaplasmosis and babesiosis can be regulated by the species of vertebrate hosts on which they obligately feed. By subjecting field-caught hosts to parasitism by larval blacklegged ticks, we found that some host species (e.g. opossums, squirrels) that are abundantly parasitized in nature kill 83 -96% of the ticks that attempt to attach and feed, while other species are more permissive of tick feeding. Given natural tick burdens we document on these hosts, we show that some hosts can kill thousands of ticks per hectare. These results indicate that the abundance of tick vectors can be regulated by the identity of the hosts upon which these vectors feed. By simulating the removal of hosts from intact communities using empirical models, we show that the loss of biodiversity may exacerbate disease risk by increasing both vector numbers and vector infection rates with a zoonotic pathogen.

Information is characterized as the reduction of uncertainty and by a change in the state of a receiving organism. Thus, organisms can acquire information about their environment that reduces uncertainty and increases their likelihood of choosing a best‐matching strategy. We define the ecology of information as the study of how organisms acquire and use information in decision‐making and its significance for populations, communities, landscapes and ecosystems. As a whole, it encompasses the reception and processing of information, decision‐making, and the ecological consequences of making informed decisions. The first two stages constitute the domains of, e.g. sensory ecology and behavioral ecology. The exploration of the consequences of information use at larger spatial and temporal scales in ecology has lagged behind these other disciplines. In our overview we characterize information, discuss statistical decision theory as a quantitative framework to analyze information and decision‐making, and discuss potential ecological ramifications. Rather than attempt a cursory review of the enormity of the scope of information we highlight information use in development, breeding habitat selection, and interceptive eavesdropping on alarm calls. Through these topics we discuss specific examples of ecological information use and the emerging ecological consequences. We emphasize recurring themes: information is collected from multiple sources, over varying temporal and spatial scales, and in many cases links heterospecifics to one another. We conclude by breaking from specific ecological contexts to explore implications of information as a central organizing principle, including: information webs, information as a component of the niche concept, and information as an ecosystem process. With information having such an enormous reach in ecology we further cast a spotlight on the potential harmful effects of anthropogenic noise and info‐disruption.

Many infectious diseases of humans are caused by pathogens that reside in nonhuman animal reservoirs and are transmitted to humans via the bite of an arthropod vector. Most vectors feed from a variety of host species that differ dramatically in their reservoir competence; that is, their probability of transmitting the infection from host to vector. We explore a conceptual model of what we termed the “dilution effect,” whereby the presence of vertebrate hosts with a low capacity to infect feeding vectors (incompetent reservoirs) dilute the effect of highly competent reservoirs, thus reducing disease risk. Using Lyme disease as an example, we demonstrate the presence and estimate the magnitude of the dilution effect for local sites in eastern New York State. We found that the prevalence of Lyme disease spirochetes, Borrelia burgdorferi, in field‐collected Ixodes ticks (37.6% and 70.5% for nymphal and adult stages, respectively) was dramatically lower than expected (∼90% and >95% for nymphal and adult stages, respectively) if ticks fed predominantly on highly competent reservoirs, white‐footed mice (Peromyscus leucopus) and eastern chipmunks (Tamias striatus). We inferred the role of additional host species using an empirically based model that incorporated data on tick burdens per host, relative population densities of hosts, and reservoir competence of each host. Assuming an empirically realistic reservoir competence of 5% for non‐mouse and non‐chipmunk hosts, we determined that alternative hosts must provide 61% and 72% of larval and nymphal meals, respectively. Using computer simulations, we assembled simulated host communities that differed in species richness, evenness, and net interactions between alternative hosts and mice. We found that increasing species richness (but not evenness) reduced disease risk. Effects were most pronounced when the most competent disease reservoirs were community dominants and when alternative hosts had a net negative influence on the dominance of mice as a host for ticks. Our results highlight a critical role of biodiversity and host community ecology in the transmission of vector‐borne zoonotic diseases that in turn has important consequences for human health.

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