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91.
Fanie Pelletier John T. Hogg Marco Festa-Bianchet 《Behavioral ecology and sociobiology》2006,60(5):645-654
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 相似文献
92.
93.
Raymond R. Tan Denny Kok Sum Ng Dominic Chwan Yee Foo 《Journal of Cleaner Production》2009,17(10):940-944
A graphical pinch-based methodology for planning retrofits for carbon capture and storage (CCS) in the power generation sector is presented in this work. CCS is widely seen as one of the essential interim technologies to mitigate greenhouse gas emissions, while still being able to utilize fossil fuels, which are relatively inexpensive and reliable in comparison to inherently low-carbon renewable resources. However, retrofitting power plants for CCS entails major capital costs as well as a reduction of thermal efficiency and power output. Thus, it is essential for planning purposes to implement the minimal extent of CCS retrofit that meets the sectoral carbon footprint targets. At the same time, it is necessary to plan for additional power generation capacity or efficiency enhancements to compensate for energy losses resulting from CCS retrofits. The simple graphical approach used in this paper is designed to determine such targets, and shares the same intuitive, insight-driven characteristics of pinch analysis techniques. A case study is shown to illustrate the methodology. 相似文献
94.
Vyverman W Verleyen E Sabbe K Vanhoutte K Sterken M Hodgson DA Mann DG Juggins S Van de Vijver B Jones V Flower R Roberts D Chepurnov VA Kilroy C Vanormelingen P De Wever A 《Ecology》2007,88(8):1924-1931
There is a long-standing belief that microbial organisms have unlimited dispersal capabilities, are therefore ubiquitous, and show weak or absent latitudinal diversity gradients. In contrast, using a global freshwater diatom data set, we show that latitudinal gradients in local and regional genus richness are present and highly asymmetric between both hemispheres. Patterns in regional richness are explained by the degree of isolation of lake districts, while the number of locally coexisting diatom genera is highly constrained by the size of the regional diatom pool, habitat availability, and the connectivity between habitats within lake districts. At regional to global scales, historical factors explain significantly more of the observed geographic patterns in genus richness than do contemporary environmental conditions. Together, these results stress the importance of dispersal and migration in structuring diatom communities at regional to global scales. Our results are consistent with predictions from the theory of island biogeography and metacommunity concepts and likely underlie the strong provinciality and endemism observed in the relatively isolated diatom floras in the Southern Hemisphere. 相似文献
95.
Xavier A. Harrison Jennifer E. York Dominic L. Cram Michelle C. Hares Andrew J. Young 《Behavioral ecology and sociobiology》2013,67(12):1915-1929
The distribution of reproductive success within societies is a key determinant of the outcomes of social evolution. Attempts to explain social diversity, therefore, require that we quantify reproductive skews and identify the mechanisms that generate them. Here, we address this priority using life history and genotypic data from >600 individuals in 40 wild groups of the cooperatively breeding white-browed sparrow weaver, Plocepasser mahali. We show that groups comprise up to six males and seven females, but within-group reproduction is completely monopolised by a single dominant male and female, while extra-group males sire 12–18 % of offspring. Strong within-group kin structure could frequently explain these monopolies, as subordinates had typically delayed dispersal from their natal groups and so frequently (1) lacked within-group outbreeding partners, and/or (2) stood to gain little from contesting dominant reproduction, being almost as related to the dominant’s young as they would have been to their own. Kin structure alone cannot account entirely for these monopolies, however, as they remained complete following the immigration of unrelated males and females. That subordinate females remain reproductively quiescent despite also showing comparable body condition to dominants, overlapping them substantially in age, and showing no evidence of elevated stress hormone levels raises the possibility that they exercise reproductive restraint due instead to a threat of action by dominants and/or deficits in offspring fitness that might arise if subordinates bred. Our findings highlight the complexity of the mechanisms that generate reproductive disparities in animal societies and the challenge of identifying them when skews are complete. 相似文献
96.
Ruhul A. Khan Stephane Salmieri Dominic Dussault Nathalie Tufenkji Jorge Uribe-Calderon Musa R. Kamal Agnes Safrany Monique Lacroix 《Journal of Polymers and the Environment》2012,20(1):43-52
Chitosan (0.1–1%, w/w), dissolved in 2% acetic acid solution, was added into 1% methylcellulose (MC)-based formulation containing
0.5% vegetable oil, 0.25% glycerol and 0.025% Tween?80. Films were prepared by casting. Puncture strength (PS), puncture deformation (PD), viscoelasticity coefficient and water
vapour permeability (WVP) of the films were measured. The PS value of 312 N/mm was observed for MC-based films containing
0.25% chitosan. Values of PD, viscoelasticity coefficient and WVP of these films were 5.0 mm, 44.1%, and 6.0 g mm/m2 day kPa, respectively. The MC-based films containing 0.25% chitosan were also exposed to gamma radiation (0.5–50 kGy). The
PS of the treated films decreased significantly from 312 at 0 kGy to 201 N/mm when treated at a dose of 50 kGy. However, WVP
values were not affected by increasing irradiation the dose used. The Fourier Transform Infrared spectroscopy supported the
molecular interactions due to addition of chitosan in MC-based films. Thermo gravimetric analysis and differential scanning
calorimetric experiments showed that thermal properties of the films were significantly improved by chitosan loading. Surface
topography of the films was studied by scanning electron microscopy and found rougher due to chitosan addition. 相似文献
97.
Jeremy Cain Charles Batchelor Dominic Waughray 《Environment, Development and Sustainability》1999,1(2):123-133
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. 相似文献
98.
Stefanie Jacob Andreas Dötsch Sarah Knoll Heinz-R. Köhler Eike Rogall Dominic Stoll Selina Tisler Carolin Huhn Thomas Schwartz Christian Zwiener Rita Triebskorn 《Environmental Sciences Europe》2018,30(1):48