Male mating effort in a polygynous ungulate

Survival and mating success are key fitness components of mammalian males. Because energy is limited, life history theory predicts trade-offs between current and future reproduction. While many studies have examined fitness trade-off in females, we know little about trade-offs faced by males. In polygynous species, male mating success is largely dependent upon intrasexual competition. Consequently, males have greater uncertainty over the benefits of a given allocation than over its costs, and the correlation between mating effort and success is likely much weaker in males than in females. We analyzed 14 years of data on the mating effort and survival of marked bighorn rams to investigate fitness trade-offs. Dominant rams defended single estrous ewes (“tending”) while subordinates attempted to copulate after separating the tending pair (“coursing”). We estimated the participation in tending and coursing for each ram and the effort in searching for breeding opportunities by each ram each year. We compared these three behavioral indices of male mating effort to demographic parameters, individual characteristics, and both yearly and long-term survival. Mating effort during the rut was unrelated to ram overwinter survival, but longevity was positively correlated with mating effort between 2 and 5 years of age. Persistent variation among rams is likely to explain this pattern, suggesting that in natural populations a few high quality males enjoy both high mating success and high survival.An erratum to this article can be found at     

Fabrication and Characterization of Biodegradable Composite Films Made of Using Poly(caprolactone) Reinforced with Chitosan

Chitosan was dissolved in 2?% aqueous acetic acid solution and the films were prepared by solution casting. Values of tensile strength (TS), tensile modulus (TM), elongation at break (Eb?%) and water vapor permeability (WVP) of the chitosan films were found to be 30?MPa, 450?MPa, 8?% and 4.7?g?mm/m²?day?kPa, respectively. Poly(caprolactone) (PCL) films were prepared from its granules by compression molding and the values of TS, TM, Eb and WVP were 14?MPa, 220?MPa, 70?% and 1.54?g?mm/m²?day?kPa, respectively. PCL was reinforced with chitosan films, and composite films were prepared by compression molding. Amount of chitosan in the composite films varied from 10 to 50?% (w/w). It was found that with the incorporation of chitosan films in PCL, both the values of TS and TM of composite films increased significantly. The highest mechanical properties were found at 50?% (w/w) of chitosan content. The Oxygen transmission rate (OTR) of composite film was found to decrease significantly than PCL films. Thermal properties of the composite were also improved as compared to PCL. The water uptake test of the composite also showed promising results with a good stability of composite films. The interface of the composite was investigated by scanning electron microscopy and showed good interfacial adhesion between PCL and chitosan films.     

A guide towards climate change adaptation in the livestock sector: adaptation options and the role of robust decision-making tools for their economic appraisal

Economic appraisal and technical effectiveness of adaptation options are key criteria for judging climate change adaptation investment decisions in all sectors. Yet relatively little methodological guidance exists for determining the most appropriate appraisal techniques for different adaptation options. This paper provides adaptation options and scopes relevant appraisal methods in agriculture focussing on livestock production specifically. We find that for many adaptation options for livestock agriculture, standard (expected) cost-benefit analysis is an appropriate tool. For adaptation options requiring long lead times or those with long lifetimes, techniques incorporating uncertainty (‘robust’ methods) are more suitable, including real options analysis, portfolio analysis and robust decision-making. From a comprehensive list of adaptation options in the livestock sector, we identify the most appropriate appraisal technique for each option and describe how the robust appraisal tools could be applied to heat stress, flood risk and water management.

     

Effects of nano-TiO(2) in combination with ambient UV-irradiation on a leaf shredding amphipod

Production and use of engineered nanoparticles, such as titanium dioxide nanoparticles (nTiO₂), is increasing worldwide, enhancing their probability to enter aquatic environments. However, direct effects of nTiO₂ as well as ecotoxicological consequences due to the interactions of nTiO₂ with environmental factors like ultraviolet (UV) irradiation on representatives of detrital food webs have not been assessed so far. Hence, the present study displayed for the first time adverse sublethal effects of nTiO₂ at concentrations as low as 0.2 mg L⁻¹ on the leaf shredding amphipod Gammarus fossarum both in presence and absence of ambient UV-irradiation following a 7-d exposure. In absence of UV-irradiation, however, the effects seemed to be driven by accumulation of nTiO₂ at the bottom of the test vessels to which the gammarids were potentially exposed. The adverse sublethal and lethal effects on gammarids caused by the combined application of nTiO₂ and ambient UV-irradiation are suggested to be driven by the formation of reactive oxygen species. In conclusion, both the accumulation of nTiO₂ at the bottom of the test vessel and the UV induced formation of reactive oxygen species clearly affected its ecotoxicity, which is recommended for consideration in the environmental risk assessment of nanoparticles.     

Bibliometric investigation of the integration of animal personality in conservation contexts

Consistent individual differences in behavior, commonly termed animal personality, are a widespread phenomenon across taxa that have important consequences for fitness, natural selection, and trophic interactions. Animal personality research may prove useful in several conservation contexts, but which contexts remains to be determined. We conducted a structured literature review of 654 studies identified by combining search terms for animal personality and various conservation subfields. We scored the relevance of personality and conservation issues for each study to identify which studies meaningfully integrated the 2 fields as opposed to surface-level connections or vague allusions. We found a taxonomic bias toward mammals (29% of all studies). Very few amphibian or reptile studies applied personality research to conservation issues (6% each). Climate change (21%), invasive species (15%), and captive breeding and reintroduction (13%) were the most abundant conservation subfields that occurred in our search, though a substantial proportion of these papers weakly integrated conservation and animal personality (climate change 54%, invasive species 51%, captive breeding and reintroduction 40%). Based on our results, we recommend that researchers strive for consistent and broadly applicable terminology when describing consistent behavioral differences to minimize confusion and improve the searchability of research. We identify several gaps in the literature that appear to be promising and fruitful avenues for future research, such as disease transmission as a function of sociability or exploration as a driver of space use in protected areas. Practitioners can begin informing future conservation efforts with knowledge gained from animal personality research.     

Integrating larval connectivity into the marine conservation decision-making process across spatial scales

Larval dispersal connectivity is typically integrated into spatial conservation decisions at regional or national scales, but implementing agencies struggle with translating these methods to local scales. We used larval dispersal connectivity at regional (hundreds of kilometers) and local (tens of kilometers) scales to aid in design of networks of no-take reserves in Southeast Sulawesi, Indonesia. We used Marxan with Connectivity informed by biophysical larval dispersal models and remotely sensed coral reef habitat data to design marine reserve networks for 4 commercially important reef species across the region. We complemented regional spatial prioritization with decision trees that combined network-based connectivity metrics and habitat quality to design reserve boundaries locally. Decision trees were used in consensus-based workshops with stakeholders to qualitatively assess site desirability, and Marxan was used to identify areas for subsequent network expansion. Priority areas for protection and expected benefits differed among species, with little overlap in reserve network solutions. Because reef quality varied considerably across reefs, we suggest reef degradation must inform the interpretation of larval dispersal patterns and the conservation benefits achievable from protecting reefs. Our methods can be readily applied by conservation practitioners, in this region and elsewhere, to integrate connectivity data across multiple spatial scales.     

Atmospheric Change and the Diversity of Aquatic Invertebrates: Are We Missing the Boat?

The response of natural systems to atmospheric change may depend critically on species diversity and on the genetic diversity (variability) found within their respective populations. Yet, most surveys of aquatic invertebrates account for neither. This may be of particular concern for benthic populations in running waters because of the considerable variability and the fragmentary nature of these habitats (e.g. isolated watersheds). In such habitats, species with limited genetic variability and/or limited dispersal capabilities (genetically differentiated populations) may be unable to track rapid environmental change, and may be more susceptible to climatic perturbations. We present a conceptual framework to illustrate some of the potential problems of ignoring population genetics when considering the impacts of global atmospheric change. We then review a simple method to assess population genetic structure and we evaluate available data on the genetic structure of North American stream invertebrates. These data indicate that benthic taxa often consist of genetically differentiated local populations, or even previously unknown species. Accordingly, our limited knowledge of population structure among benthic invertebrates may result in the unwitting loss of genetic and/or species diversity. Enhanced taxonomic research incorporating molecular techniques is clearly warranted. Conservation strategies based on the preservation and remediation of a diversity of aquatic habitats are likely to be our best means of ensuring species and genetic diversity of invertebrate taxa.     

Steady‐state field‐scale gas permeability estimation and pore‐gas velocity calculation in a domain open to the atmosphere

Field‐scale estimation of gas permeability and subsequent computation of pore‐gas velocity profiles are critical elements of sound soil venting design. It has been our experience, however, in U.S. Environmental Protection Agency's (EPA's) technical assistance program, provided by the Office of Research and Development in support EPA regional offices, that many venting practitioners are unaware of equations and data interpretation methods appropriate for gas permeability estimation and pore‐gas velocity computation. To ameliorate this situation, we use data collected at a U.S. Coast Guard Station in Traverse City, Michigan, to demonstrate gets permeability estimation and pore‐gas velocity calculation for steady‐state, axisymmetric, two‐dimensional gas flow in a domain open to the atmosphere. For gas permeability estimation, we use random guesses constrained with decreasing intervals of radial and vertical permeabilityand analysis of root mean square errors to ensure attainment of a global versus local minimum. We demonstrate confidence in permeability estimation by providing plots of observed versus simulated pressure response. Finally, we illustrate how plots of pore‐gas velocity as a function of distance and flow rate can be helpful in venting design.     

Belief Networks: A Framework for the Participatory Development of Natural Resource Management Strategies

Successful long-term management of natural resources requires the development of strategies which recognise the constraints pertaining to the environmental system and can therefore be realistically expected to work. This paper presents a new technique for strategy formulation using belief networks, a framework based on Bayesian probability calculus that supports the investigation of complex environmental systems by the user and analysis of all constraints. While mathematical in nature, belief networks are superficially simple and allow concepts to be expressed in terms with which a wide range of user will be familiar. This offers a participatory approach to the development of management strategies through consideration of the impact of potential management options with consequent benefits for strategy implementation.