Habitat functional response mitigates reduced foraging opportunity: implications for animal fitness and space use

Context

Animals selectively use landscapes to meet their energetic needs, and trade-offs in habitat use may depend on availability and environmental conditions. For example, habitat selection at high temperatures may favor thermal cover at the cost of reduced foraging efficiency under consistently warm conditions.

Objective

Our objective was to examine habitat selection and space use in distinct populations of moose (Alces alces). Hypothesizing that endotherm fitness is constrained by heat dissipation efficiency, we predicted that southerly populations would exhibit greater selection for thermal cover and reduced selection for foraging habitat.

Methods

We estimated individual step selection functions with shrinkage for 134 adult female moose in Minnesota, USA, and 64 in Ontario, Canada, to assess habitat selection with variation in temperature, time of day, and habitat availability. We averaged model coefficients within each site to quantify selection strength for habitats differing in forage availability and thermal cover.

Results

Moose in Ontario favored deciduous and mixedwood forest, indicating selection for foraging habitat across both diel and temperature. Habitat selection patterns of moose in Minnesota were more dynamic and indicated time- and temperature-dependent trade-offs between use of foraging habitat and thermal cover.

Conclusions

We detected a scale-dependent functional response in habitat selection driven by the trade-off between selection for foraging habitat and thermal cover. Landscape composition and internal state interact to produce complex patterns of space use, and animals exposed to increasingly high temperatures may mitigate fitness losses from reduced foraging efficiency by increasing selection for foraging habitat in sub-prime foraging landscapes.

     

Factors influencing female home range sizes in elk (<Emphasis Type="Italic">Cervus elaphus</Emphasis>) in North American landscapes

Home range size is a result of individual movements and the spatial distribution of a population. While body size, sex, and age are known to influence the area over which an animal ranges, it remains uncertain how landscape heterogeneity influences home range size. We examined elk (Cervus elaphus) seasonal home range sizes in relation to the quantity and spatial heterogeneity of forage biomass, forest cover, topography, snow–water equivalents, and landscape structure in three study landscapes: Yellowstone National Park, Wyoming, USA; eastern slopes of the Canadian Rockies, Alberta; and northern Wisconsin, USA. We used a 95% fixed kernel estimator to measure the home range size and location of all elk. To identify the scales at which important factors influenced home range sizes, we quantified environmental variables within the estimated home range polygon and within concentric circles with radii of 1000, 2000, 3000, 4000, and 5000 m from the home range center. Results indicate that there was an inverse relationship between forage biomass and summer and winter home range sizes in Alberta and Wisconsin, however the relationship was positive in Yellowstone. The size of summer and winter home ranges was positively related to percent forest cover; however this relationship was significant only when forest cover was quantified within the home range polygon or radii that were greater than or equal to 3000 m. Winter home ranges also had a positive relationship with snow–water equivalents. The predictive strength of summer home range models was greatest when landscape variables were quantified within the concentric circles with a radius of 3000 m or more, whereas the predictive strength of the winter models was greatest within the estimated home range polygon. Results suggest that elk ranging patterns reflected complex trade-offs that affect foraging, group dynamics, movement energetics, predation avoidance and thermal regulation. The multi-scale analysis indicates that elk based home ranging decisions on an area equal to their home range, but areas outside of the estimated home range were also important.     

Identification of Cabernet Sauvignon anthocyanin gut microflora metabolites

Anthocyanins are polyphenol antioxidants that have been shown to prevent many chronic diseases, including colon cancer. The compounds are largely metabolized by various enzymes and bacteria in the large intestine, and the health benefits of consuming foods rich in anthocyanins could be due mostly to the effects of these metabolites. In this study, the contents of the large intestine of pigs were used to model anthocyanin metabolism because pig and human intestinal microflora are similar. An anthocyanin extract from Cabernet Sauvignon grapes that contained delphinidin-3-glucoside, petunidin-3-glucoside, peonidin-3-glucoside, and malvidin-3-glucoside was employed. The extract was incubated anaerobically in the contents of the large intestine of freshly slaughtered pigs for 0, 0.5, and 6 h (final concentrations of 20.9, 28.2, 61.4, and 298.0 microM of the above anthocyanin compounds, respectively, at t = 0 h). Anthocyanins and their metabolites were measured by LC-ESI-MS. After 6 h, anthocyanins were no longer detected, and three metabolites were identified as 3-O-methylgallic acid, syringic acid, and 2,4,6-trihydroxybenzaldehyde. Results from this study suggest that consumption of Cabernet Sauvignon grape anthocyanins could lead to the formation of specific metabolites in the human gut, and it is possible that these metabolites offer the protective effect against colon cancer attributed to anthocyanin consumption.     

RNA‐based biocontrol compounds: current status and perspectives to reach the market

Facing current climate challenges and drastically reduced chemical options for plant protection, the exploitation of RNA interference (RNAi) as an agricultural biotechnology tool has unveiled possible new solutions to the global problems of agricultural losses caused by pests and other biotic and abiotic stresses. While the use of RNAi as a tool in agriculture is still limited to a few transgenic crops, and only adopted in restricted parts of the world, scientists and industry are already seeking innovations in leveraging and exploiting the potential of RNAi in the form of RNA‐based biocontrol compounds for external applications. Here, we highlight the expanding research and development pipeline, commercial landscape and regulatory environment surrounding the pursuit of RNA‐based biocontrol compounds with improved environmental profiles. The commitments of well‐established agrochemical companies to invest in research endeavours and the role of start‐up companies are crucial for the successful development of practical applications for these compounds. Additionally, the availability of standardized guidelines to tackle regulatory ambiguities surrounding RNA‐based biocontrol compounds will help to facilitate the entire commercialization process. Finally, communication to create awareness and public acceptance will be key to the deployment of these compounds. © 2019 Society of Chemical Industry     

Detection and isolation of Helicobacter mustelae from stoats in New Zealand

AIM: To determine the incidence of Helicobacter mustelae in stoats (Mustela erminea) in New Zealand. METHODS: Helicobacter-like organisms and total genomic DNA were isolated from gastric tissue of stoats and identified using a combination of bacterial culture, phenotypic testing and molecular techniques. RESULTS: A Helicobacter-specific 16S rRNA polymerase chain reaction product was detected in 16/32 gastric tissue biopsies tested. Nine of 13 partially sequenced 16S rRNA DNA identified H. mustelae 16S DNA. Bacteria, subsequently identified as H. mustelae, were successfully cultured from the stomachs of 4/32 stoats. Other Helicobacter species were also identified by DNA sequence analysis, but were not cultured. CONCLUSIONS: Helicobacter mustelae is present in stoats from both the North and South Islands of New Zealand.