Biology subjects

Williams, D. R.

Publications and source records attributed to Williams, D. R..

3 recordsLinked to original sources

bioRxiv2020

Dynamic Changes in Fecal Bacterial Microbiota of Dairy Cattle across the Production Line

Bacteria play important roles in the gastrointestinal tract (GIT) of dairy cattle as the communities are responsible for host health, growth and production performance. However, a systematic characterization and comparison of microbial communities in the GIT of cattle housed in different management units on a modern dairy are still lacking. In this study, we used 16S rRNA sequencing to evaluate the fecal bacterial communities of 90 dairy cattle raised and housed in 12 clearly defined management units on a modern dairy farm. We found that -diversity differed between several pairs of management units, especially between the hutch calves (management unit 1) and the other units except post weaned heifers (management unit 2). Although {beta}-diversity revealed that most of the samples did not cluster according to their management unit membership except management unit 1, in which the samples grouped and separated from others, we observed three major clusters. Besides the hutch calves (management unit 1), most samples from the other 11 units formed two distinct clusters and the relative abundance of Patescibacteria might be the reason for the separation. Moreover, we identified 212 amplicon sequence variants (ASVs) with relative abundances > 0.1% in more than 10% of the total samples that had significantly different abundances in these units. Furthermore, we found that, as the calves aged, 19 ASVs that were exclusively detected in unit 1, gradually degraded and never reoccurred in other management units. Lastly, we recognized 181 pairs of interactions between 61 ASVs with possibly strong synergistic or antagonistic relationships. These results suggest the enteric microbial communities of dairy cattle housed in different management units are quite dynamic. IMPORTANCEBacterial communities of GIT are crucial for ruminants, such as dairy cattle since they contribute to not only the cattles physiology and health but also milk production and food safety that are closely related to human health. Both scientifically and agriculturally, it is necessary to have deep insights into the composition and changes of the bacteria on modern dairy farms. In this study, we provided the profiles of fecal bacterial communities of dairy cattle in each management unit on a modern dairy and described how the enteric microbial communities changed across these management units. The findings have implications for improving animal health, dairy production, farm management, and food safety.

microbiology↗

bioRxiv2020

Poor availability of context-specific evidence hampers decision-making in conservation

Evidence-based conservation relies on robust and relevant evidence. Practitioners often prefer locally relevant studies whose results are more likely to be transferable to the context of planned conservation interventions. To quantify the availability of relevant evidence for amphibian and bird conservation we reviewed Conservation Evidence, a database of quantitative tests of conservation interventions. Studies were geographically clustered and found at extremely low densities - fewer than one study was present within a 2,000 km radius of a given location. The availability of relevant evidence was extremely low when we restricted studies to those studying biomes or taxonomic orders containing high percentages of threatened species, compared to the most frequently studied biomes and taxonomic orders. Further constraining the evidence by study design showed that only 17-20% of amphibian and bird studies used robust designs. Our results highlight the paucity of evidence on the effectiveness of conservation interventions, and the disparity in evidence for local contexts that are frequently studied and those where conservation needs are greatest. Addressing the serious global shortfall in context-specific evidence requires a step change in the frequency of testing conservation interventions, greater use of robust study designs and standardized metrics, and methodological advances to analyze patchy evidence bases.

ecology↗

bioRxiv2019

The challenge of heterogeneous evidence in conservation

Conservation efforts to tackle the current biodiversity crisis need to be as efficient and effective as possible. To inform decision-makers of the most effective conservation actions, it is important to identify biases and gaps in the conservation literature to prioritize future evidence generation. We assessed the state of this global literature base using the Conservation Evidence database, a comprehensive collection of quantitative tests of conservation actions (interventions) from the published literature. For amphibians and birds, we investigated the nature of Conservation Evidence spatially and taxonomically, as well as by biome, effectiveness metrics, and study design. Studies were heavily concentrated in Western Europe and North America for birds and particularly amphibians. Studies that used the most robust study designs - Before-After Control-Impact and Randomized Controlled Trials - were also the most geographically restricted. Furthermore, there was no relationship between the number of studies in each 1x1 degree grid cell and the number of species, threatened species or data-deficient species. Taxonomic biases and gaps were apparent for amphibians and birds - some orders were absent from the evidence base and others were poorly represented relative to the proportion of threatened species they contained. Temperate forest and grassland biomes were highly represented, which reinforced observed geographic biases. Various metrics were used to evaluate the effectiveness of a given conservation action, potentially making studies less directly comparable and evidence synthesis more difficult. We also found that the least robust study designs were the most commonly used; studies using robust designs were scarce. Future research should prioritize testing conservation actions on threatened species outside of Western Europe and North America. Standardizing metrics and improving the robustness of study designs used to test conservation actions would also improve the quality of the evidence base for synthesis and decision-making.

ecology↗