Non-lethal isolation of the fungal pathogen Batrachochytrium dendrobatidis (Bd) from amphibians.

The ability to isolate and purify pathogens is important for the study of infectious disease. A protocol for isolating Batrachochytrium dendrobatidis (Bd), a lethal pathogen of amphibians, has been available for over a decade, but the method relies on sacrificing infected animals. We validated a non-lethal protocol for Bd isolation that uses biopsy punches from toe webbing to collect skin samples from live amphibians in remote field locations. We successfully isolated Bd from the Cascades frog Rana cascadae and found a positive association between Bd infection and probability of Bd growth in culture. Recapture rates of sampled animals suggest that our isolation protocol did not affect frog survival. The ability to collect isolates from live animals will facilitate investigations of the biology of Bd and enhance amphibian conservation efforts.

Greater Species Richness of Bacterial Skin Symbionts Better Suppresses the Amphibian Fungal Pathogen Batrachochytrium Dendrobatidis.

The symbiotic microbes that grow in and on many organisms can play important roles in protecting their hosts from pathogen infection. While species diversity has been shown to influence community function in many other natural systems, the question of how species diversity of host-associated symbiotic microbes contributes to pathogen resistance is just beginning to be explored. Understanding diversity effects on pathogen resistance could be particularly helpful in combating the fungal pathogen Batrachochytrium dendrobatidis (Bd) which has caused dramatic population declines in many amphibian species and is a major concern for amphibian conservation. Our study investigates the ability of host-associated bacteria to inhibit the proliferation of Bd when grown in experimentally assembled biofilm communities that differ in species number and composition. Six bacterial species isolated from the skin of Cascades frogs (Rana cascadae) were used to assemble bacterial biofilm communities containing 1, 2, 3, or all 6 bacterial species. Biofilm communities were grown with Bd for 7 days following inoculation. More speciose bacterial communities reduced Bd abundance more effectively. This relationship between bacterial species richness and Bd suppression appeared to be driven by dominance effects-the bacterial species that were most effective at inhibiting Bd dominated multi-species communities-and complementarity: multi-species communities inhibited Bd growth more than monocultures of constituent species. These results underscore the notion that pathogen resistance is an emergent property of microbial communities, a consideration that should be taken into account when designing probiotic treatments to reduce the impacts of infectious disease.

Belonging in STEM: an interactive, iterative approach to create and maintain a diverse learning community.

Diversity is a key driver of scientific innovation, yet fields in science, technology, engineering, and mathematics (STEM) have struggled to retain diverse communities. Research suggests that fostering a sense of belonging is critical for retaining diversity. We propose an iterative process that aims to improve sense of belonging among laboratory (lab) members through self-reflection and community collective action.

Marine subsidies change short-term foraging activity and habitat utilization of terrestrial lizards.

Resource pulses are brief periods of unusually high resource abundance. While population and community responses to resource pulses have been relatively well studied, how individual consumers respond to resource pulses has received less attention. Local consumers are often the first to respond to a resource pulse, and the form and timing of individual responses may influence how the effects of the pulse are transmitted throughout the community. Previous studies in Bahamian food webs have shown that detritivores associated with pulses of seaweed wrack provide an alternative prey source for lizards. When seaweed is abundant, lizards (Anolis sagrei) shift to consuming more marine-derived prey and increase in density, which has important consequences for other components of the food web. We hypothesized that the diet shift requires individuals to alter their habitat use and foraging activity and that such responses may happen very rapidly. In this study, we used recorded video observations to investigate the immediate responses of lizards to an experimental seaweed pulse. We added seaweed to five treatment plots for comparison with five control plots. Immediately after seaweed addition, lizards decreased average perch height and increased movement rate, but these effects persisted for only 2 days. To explore the short-term nature of the response, we used our field data to parametrize heuristic Markov chain models of perch height as a function of foraging state. These models suggest a "Synchronized-satiation Hypothesis," whereby lizards respond synchronously and feed quickly to satiation in the presence of a subsidy (causing an initial decrease in average perch height) and then return to the relative safety of higher perches. We suggest that the immediate responses of individual consumers to resource pulse events can provide insight into the mechanisms by which these consumers ultimately influence community-level processes.