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411.
Olivier Pays Simon P. Blomberg Pierre-Cyril Renaud François-René Favreau Peter J. Jarman 《Behavioral ecology and sociobiology》2010,64(3):443-454
In group-forming prey species, theory assumes that individuals within groups should scan independently of one another, with
vigilance sequences being relatively unpredictable, making interscan durations highly variable. We attempted to detect any
divergence from randomness in the scanning process in three mammalian prey species phylogenetically and geographically separated
and exposed to different levels of predation: waterbuck, Kobus ellipsiprymnus defassa, under a high observed predation risk, eastern grey kangaroo, Macropus giganteus, still experiencing occasional predation and European roe deer, Capreolus capreolus, under a very low natural predation risk. Our results revealed that the focal interscan duration increased when the duration
of the preceding interscan increased, whatever the studied species and the predation risk that its individuals experienced,
and decreased with the preceding scan duration in two species under, respectively, occasional and low predation risks. The
exponential distribution was the tested model that fitted the observed distributions of interscan durations least well. We
discuss what can trigger non-randomness in scanning, through a non-homogenous Poisson process, at both intra-individual and
inter-individual levels, particularly with regard to previous studies that have demonstrated synchronisation of vigilance
in such mammals. Our results suggest the need to reconsider any assumption of randomness in scanning in the basic model predicting
form and frequency of scanning behaviour by prey species. 相似文献
412.
Glenn J. Lurman Till Blaser Miles Lamare Lloyd S. Peck Simon Morley 《Marine Biology》2010,157(4):907-913
Habitat temperature and mitochondrial volume density (Vv(mt,mf)) are negatively correlated in fishes, while seasonal acclimatization may increase Vv(mt,mf) or the surface density of the mitochondrial cristae (Sv(im,mt)). The effect of temperature on invertebrate mitochondria is essentially unknown. A comparison of two articulate brachiopod
species, Liothyrella uva collected from Rothera Station, Antarctica in summer 2007, and Liothyrella neozelanica collected from Fiordland, New Zealand in winter 2007 and summer 2008, revealed a higher Vv(mt,mf) in the Antarctic brachiopod. The Sv(im,mt) was, however, significantly lower, indicating the Antarctic brachiopods have more, less reactive mitochondria. L. uva, from the colder environment, had larger adductor muscles in both absolute and relative terms than the temperate L. neozelanica. Furthermore, a seasonal comparison (winter vs. summer) in L. neozelanica showed that the absolute and relative size of the adductor increased in winter, Vv(mt,mf) was unchanged, and Sv(im,mt) was significantly increased. Thus, seasonal acclimatization to the cold resulted in the same number of more reactive mitochondria.
L. neozelanica was clearly able to adapt to seasonal changes using a different mechanism, i.e. primarily through regulation of cristae surface
area as opposed to mitochondrial volume density. Furthermore, given the evolutionary age of these living fossils (i.e. approximately
550 million years), this suggests that mitochondrial plasticity has roots extending far back into evolutionary history. 相似文献
413.
Periphyton samples from Water Conservation Areas, Big Cypress National Preserve, and Everglades National Park in south Florida were analyzed for concentrations of total mercury, methylmercury, nitrogen, phosphorus, organic carbon, and inorganic carbon. Concentrations of total mercury in periphyton decrease slightly along a gradient from north‐to‐south. Both total mercury and methylmercury are positively correlated with organic carbon, nitrogen and phosphorus in periphyton. In horizontal sections of periphyton mats, total mercury concentrations tend to be largest at the tops and bottoms of the mats. Methylmercury concentrations tend to be the largest near the bottom of mats. These localized elevated concentrations of methylmercury suggest that there are “hot spots”; of methylmercury in periphyton. 相似文献
414.
Arturo Perez-Vazquez Simon Anderson Richard Wiltshire Robert Fraser 《国际发展与全球生态学杂志》2013,20(2):103-112
The English derive a wide range of values from allotments, but nearly 35% of allotments have disappeared in the last 20 years. The real value of allotments has probably been underestimated. The contingent valuation method (CVM) was used to give a monetary value to benefits derived from allotments by allotment holders and local residents. The study was conducted in southeast England (Wye and Ashford, Kent and Greater London). A postal survey with open-ended questions was filled in by 124 allotment holders and 74 residents. Respondents were asked to express their maximum willingness to pay for allotments (WTP) and the minimum willingness to accept (WTA) compensation for loss of allotments. The mean annual WTP for keeping allotments of allotment holders were £78.93, £35.64 and £79.43, and for local residents were £41.66, £46.14 and £283.57, in Wye, Ashford and London, respectively. The allotment holders' WTP was strategically more than WTA compensation and they were only willing to pay rent for using allotments, not for retaining them. 相似文献
415.
Lisette Martine Braman Maarten Krispijn van Aalst Simon J. Mason Pablo Suarez Youcef Ait‐Chellouche Arame Tall 《Disasters》2013,37(1):144-164
In 2008, the International Federation of Red Cross and Red Crescent Societies (IFRC) used a seasonal forecast for West Africa for the first time to implement an Early Warning, Early Action strategy for enhanced flood preparedness and response. Interviews with disaster managers suggest that this approach improved their capacity and response. Relief supplies reached flood victims within days, as opposed to weeks in previous years, thereby preventing further loss of life, illness, and setbacks to livelihoods, as well as augmenting the efficiency of resource use. This case demonstrates the potential benefits to be realised from the use of medium‐to‐long‐range forecasts in disaster management, especially in the context of potential increases in extreme weather and climate‐related events due to climate variability and change. However, harnessing the full potential of these forecasts will require continued effort and collaboration among disaster managers, climate service providers, and major humanitarian donors. 相似文献
416.
Amanda J. Gilby Enrico Sorato Simon C. Griffith 《Behavioral ecology and sociobiology》2012,66(11):1519-1529
Differential resource allocation by females across the laying sequence has been hypothesised as a mechanism through which females could either compensate nestlings that hatch last in asynchronous broods or promote brood reduction. In this study we artificially incubated eggs and cross-fostered offspring to manipulate nestlings’ position in the hatching order, to identify whether the competitive ability of nestlings is dependent on position in the laying sequence. In both control and experimentally reversed broods, first hatched chicks had a higher survival than last hatched siblings. Yet, nestlings that hatched from eggs laid in the second half of a clutch begged with a greater intensity than nestlings hatched from eggs laid in the first half of a clutch. In natural broods, the greater begging competitiveness of nestlings from later-laid eggs led to a moderation of sibling competition and these nestlings achieved the same body size and weight as nestlings from eggs laid in the first half of the clutch. The lack of a substantial difference in the size and condition of surviving nestlings in respect to laying order suggests that differential resource allocation across the egg-laying sequence partially compensates for hatching last in asynchronous broods and reduces the negative effects of the nestling size hierarchy. The effect of laying order, brood size and experimental treatment also differed for male and female nestlings. Our study highlights the need to be aware of the complex and subtle effects of nestling sex and laying sequence when investigating genetic and environmental influences on individual fitness. 相似文献
417.
Human male height is associated with mate choice and intra-sexual competition, and therefore potentially with reproductive
success. A literature review (n = 18) on the relationship between male height and reproductive success revealed a variety of relationships ranging from negative
to curvilinear to positive. Some of the variation in results may stem from methodological issues, such as low power, including
men in the sample who have not yet ended their reproductive career, or not controlling for important potential confounders
(e.g. education and income). We investigated the associations between height, education, income and the number of surviving
children in a large longitudinal sample of men (n = 3,578; Wisconsin Longitudinal Study), who likely had ended their reproductive careers (e.g. > 64 years). There was a curvilinear
association between height and number of children, with men of average height attaining the highest reproductive success.
This curvilinear relationship remained after controlling for education and income, which were associated with both reproductive
success and height. Average height men also married at a younger age than shorter and taller men, and the effect of height
diminished after controlling for this association. Thus, average height men partly achieved higher reproductive success by
marrying at a younger age. On the basis of our literature review and our data, we conclude that men of average height most
likely have higher reproductive success than either short or tall men. 相似文献
418.
419.
Watson SJ Taylor RS Nimmo DG Kelly LT Haslem A Clarke MF Bennett AF 《Ecological applications》2012,22(2):685-696
Fire is both a widespread natural disturbance that affects the distribution of species and a tool that can be used to manage habitats for species. Knowledge of temporal changes in the occurrence of species after fire is essential for conservation management in fire-prone environments. Two key issues are: whether postfire responses of species are idiosyncratic or if multiple species show a limited number of similar responses; and whether such responses to time since fire can predict the occurrence of species across broad spatial scales. We examined the response of bird species to time since fire in semiarid shrubland in southeastern Australia using data from surveys at 499 sites representing a 100-year chronosequence. We used nonlinear regression to model the probability of occurrence of 30 species with time since fire in two vegetation types, and compared species' responses with generalized response shapes from the literature. The occurrence of 16 species was significantly influenced by time since fire: they displayed six main responses consistent with generalized response shapes. Of these 16 species, 15 occurred more frequently in mid- or later-successional vegetation (> 20 years since fire), and only one species occurred more often in early succession (< 5 years since fire). The models had reasonable predictive ability for eight species, some predictive ability for seven species, and were little better than random for one species. Bird species displayed a limited range of responses to time since fire; thus a small set of fire ages should allow the provision of habitat for most species. Postfire successional changes extend for decades and management of the age class distribution of vegetation will need to reflect this timescale. Response curves revealed important seral stages for species and highlighted the importance of mid- to late-successional vegetation (> 20 years). Although time since fire clearly influences the distribution of numerous bird species, predictive models of the spatial distribution of species in fire-prone landscapes need to incorporate other factors in addition to time since fire. 相似文献
420.
Simon T. Belt Thomas A. Brown Patricia Cabedo Sanz Alba Navarro Rodriguez 《Environmental Chemistry Letters》2012,10(2):189-192
IP25 is a highly branched isoprenoid and an organic geochemical biomarker that is produced by some Arctic sea ice diatoms. IP25 has previously been used in Arctic palaeo sea ice reconstruction studies and as a tracer for studying Arctic food webs. Here,
the molecular structure of IP25 has been confirmed by 1H and 13C NMR spectroscopy following large-scale extraction from marine sediments obtained from the Canadian Arctic and purification
using a combination of open-column and HPLC chromatographic methods. The structure of IP25 was consistent between the three different sampling locations and was identical to that found previously for this biomarker
following synthesis from a closely related highly branched isoprenoid diene. Since this study represents the first structural
characterisation of IP25 in sediments, future analysis of sedimentary IP25 for palaeo Arctic sea ice reconstructions can be carried out with much greater confidence. 相似文献