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591.
The study of ecological differences among coexisting microparasites has been largely neglected, but it addresses important and unusual issues because there is no clear distinction in such cases between conventional (resource) and apparent competition. Here patterns in the population dynamics are examined for four species of Bartonella (bacterial parasites) coexisting in two wild rodent hosts, bank voles (Clethrionomys glareolus) and wood mice (Apodemus sylvaticus). Using generalized linear modeling and mixed effects models, we examine, for these four species, seasonal patterns and dependencies on host density (both direct and delayed) and, having accounted for these, any differences in prevalence between the two hosts. Whereas previous studies had failed to uncover species differences, here all four were different. Two, B. doshiae and B. taylorii, were more prevalent in wood mice, and one, B. birtlesii, was more prevalent in bank voles. B. birtlesii, B. grahamii, and B. taylorii peaked in prevalence in the fall, whereas B. doshiae peaked in spring. For B. birtlesii in bank voles, density dependence was direct, but for B. taylorii in wood mice density dependence was delayed. B. birtlesii prevalence in wood mice was related to bank vole density. The implications of these differences for species coexistence are discussed. 相似文献
592.
Pius Lee Youhua Tang Daiwen Kang Jeff McQueen Marina Tsidulko Ho-Chun Huang Sarah Lu Mary Hart Hsin-Mu Lin Shaocai Yu Geoff DiMego Ivanka Stajner Paula Davidson 《Environmental Fluid Mechanics》2009,9(1):23-42
Discrepancies in grid structure, dynamics and physics packages in the offline coupled NWS/NCEP NAM meteorological model with
the U.S. Environmental Protection Agency Community Multiscale Air Quality (CMAQ) model can give rise to inconsistencies. This
study investigates the use of three vertical mixing schemes to drive chemistry tracers in the National Air Quality Forecast
Capability (NAQFC). The three schemes evaluated in this study represent various degrees of coupling to improve the commonality
in turbulence parameterization between the meteorological and chemistry models. The methods tested include: (1) using NAM
predicted TKE-based planetary boundary height, h, as the prime parameter to derive CMAQ vertical diffusivity; (2) using the NAM mixed layer depth to determine h and then proceeding as in (1); and (3) using NAM predicted vertical diffusivity directly to parameterize turbulence mixing
within CMAQ. A two week period with elevated surface O3 concentrations during the summer 2006 has been selected to test these schemes in a sensitivity study. The study results are
verified and evaluated using the EPA AIRNow monitoring network and other ozonesonde data. The third method is preferred a
priori as it represents the tightest coupling option studied in this work for turbulent mixing processes between the meteorological
and air quality models. It was found to accurately reproduce the upper bounds of turbulent mixing and provide the best agreement
between predicted h and ozonesonde observed relative humidity profile inferred h for sites investigated in this study. However, this did not translate into the best agreement in surface O3 concentrations. Overall verification results during the test period of two weeks in August 2006, did not show superiority
of this method over the other 2 methods in all regions of the continental U.S. Further efforts in model improvement for the
parameterizations of turbulent mixing and other surface O3 forecast related processes are warranted. 相似文献
593.
E. Tobias Krause Christoph Brummel Sarah Kohlwey Markus C. Baier Caroline Müller Francesco Bonadonna Barbara A. Caspers 《Behavioral ecology and sociobiology》2014,68(11):1819-1827
Although birds have recently been shown to possess olfactory abilities and to use chemical cues in communication, limited effort has been made to demonstrate the use of odorants in social contexts. Even less is known regarding the use of odorants in species recognition. The ability to recognize conspecifics should be more pronounced in social species. This study investigated the importance of olfactory cues in species recognition in females of two estrildid finch species with different levels of sociality. Combining odor preference tests with chemical analyses, we surveyed whether female zebra finches and diamond firetails are able to distinguish between the species based on volatile traits and whether individuals exhibit species-specific differences in body odorants. Zebra finches are more social than diamond firetails; nevertheless, both species have an overlapping distribution area. Applying an experimental Y-maze paradigm, we showed that zebra finches can use differences in their species odor fingerprints and displayed a significant preference for the odor of conspecifics over that of heterospecifics, whereas diamond firetails did not reveal a preference. Using gas chromatography and mass spectrometry, we demonstrated that body odorants of the two species were significantly different in relative composition. This finding demonstrates the potential importance of olfactory cues in species recognition, at least in social bird species. Even these two closely related species displayed remarkable differences in their responsiveness to similar chemical cues, which might be caused by species-specific differences in ecology, physiology, or evolution. 相似文献
594.
Trevor J. Willis Christopher J. Sweeting Sarah J. Bury Sean J. Handley Julie C. S. Brown Debbie J. Freeman Dan G. Cairney Michael J. Page 《Marine Biology》2013,160(7):1633-1644
Using non-lethal tissue sampling for stable isotope analysis has become standard in many fields, but not for fishes, despite being desirable when species are rare or protected, when repeated sampling of individuals is required or where removal may bias other analyses. Here, we examine the utility of fish dorsal fin membrane as an alternative to muscle for analyzing δ13C and δ15N ratios in two reef fish species (blue cod Parapercis colias and spotty Notolabrus celidotus) that have differing feeding modes. Both species exhibited evidence of size-based feeding from fin δ15N values, but not from muscle. Blue cod fin δ15N increased steadily throughout the sampled size range (213–412 mm fork length), whereas spotty exhibited a distinct ontogenetic diet shift at approximately 120–140 mm fork length after which size-based feeding did not occur. Fin membrane was higher than muscle in δ13C in both species and in δ15N for blue cod, but fin δ15N was lower than muscle in spotty. The δ13C and δ15N fin–muscle offsets were constant in spotty regardless of size, while in blue cod, δ13C was constant with fish size, but δ15N offsets increased with increasing fish size. Non-lethal sampling utilizing fin tissue can be employed to estimate stable isotope values of muscle in fishes, but it is necessary to assess relationships among tissues and the effects of fish size on isotope values a priori for each species studied. Our data indicated that fin membrane may be a more sensitive tissue than muscle for detecting size-based feeding in some fish species using stable isotopes. A critical literature review revealed inconsistencies in tissue types tested, little understanding of tissue-specific trophic shift or turnover rates, and pseudo-replicated analyses leading to erroneous postulating of 1:1 relationships between tissues. 相似文献
595.
Nathalie Hilmi Denis Allemand Sam Dupont Alain Safa Gunnar Haraldsson Paulo A. L. D. Nunes Chris Moore Caroline Hattam Stéphanie Reynaud Jason M. Hall-Spencer Maoz Fine Carol Turley Ross Jeffree James Orr Philip L. Munday Sarah R. Cooley 《Marine Biology》2013,160(8):1773-1787
Ocean acidification is increasingly recognized as a component of global change that could have a wide range of impacts on marine organisms, the ecosystems they live in, and the goods and services they provide humankind. Assessment of these potential socio-economic impacts requires integrated efforts between biologists, chemists, oceanographers, economists and social scientists. But because ocean acidification is a new research area, significant knowledge gaps are preventing economists from estimating its welfare impacts. For instance, economic data on the impact of ocean acidification on significant markets such as fisheries, aquaculture and tourism are very limited (if not non-existent), and non-market valuation studies on this topic are not yet available. Our paper summarizes the current understanding of future OA impacts and sets out what further information is required for economists to assess socio-economic impacts of ocean acidification. Our aim is to provide clear directions for multidisciplinary collaborative research. 相似文献
596.
Aaron P. Maloy Peter Nelle Sarah C. Culloty John W. Slater Chris Harrod 《Marine Biology》2013,160(2):479-490
Accurate field data on trophic interactions for suspension feeders are lacking, and new approaches to dietary analysis are necessary. Polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) was integrated with stable isotope analysis to examine dietary patterns in suspension-feeding Mytilus spp. from seven spatially discrete locations within a semi-enclosed marine bay (Strangford Lough, Northern Ireland) during June 2009. Results of the two methods were highly correlated, reflecting dietary variation in a similar manner. Variation in PCR-DGGE data was more strongly correlated with the principal environmental gradient (distance from the opening to the Irish Sea), while values of δ 13C and δ 15N became progressively enriched, suggesting a greater dependence on animal tissue and benthic microalgae. Diatoms and crustaceans were the most frequently observed phylotypes identified by sequencing, but specific DNA results provided little support for the trophic trends observed in the stable isotope data. This combined approach offers an increased level of trophic insight for suspension feeders and could be applied to other organisms. 相似文献
597.
The invasive mussel Mytilus galloprovincialis and the indigenous mussel Perna perna coexist intertidally on the south coast of South Africa through partial vertical habitat segregation: M. galloprovincialis dominates the upper shore and P. perna the lower shore. Recruitment patterns can explain the zonation of P. perna, but not the invasive species. We examined the role of post-recruitment interactions by measuring spatial and temporal differences
in adult growth and mortality rates of the two species. Specifically, we tested the hypothesis that interspecific differences
in growth and mortality reflect adult distribution patterns. The two study locations, Plettenberg Bay and Tsitsikamma, are
70 km apart with two sites (separated by 300–400 m) per location, each divided into three vertical zones. Growth was measured
seasonally using different marking methods in 2001 and 2003. Cumulative adult mortality was measured through summer in 2003/2004.
Both species generally grew more slowly upshore, but they showed different effects of season. For P. perna, growth was significantly reduced in winter in the low zone, but unaffected by season in the high zone. For M. galloprovincialis, growth was either unaffected by season or increased in winter, even in the high zone. Thus, growth of P. perna and M. galloprovincialis was reduced under cool winter and warm summer temperatures, respectively; and while growth was more similar between species
in summer, M. galloprovincialis grew much faster than P. perna in winter. Mortality of P. perna increased upshore. For M. galloprovincialis, mortality was not zone-dependent and was significantly greater than for P. perna on the low-shore and (generally) across the shore in Tsitsikamma. Both species had higher growth and mortality rates in Plettenberg
Bay than in Tsitsikamma. Thus, P. perna seems able to maintain spatial dominance on the low-shore and at certain sites because of higher mortality of M. galloprovincialis. We conclude that seasonality in growth of the two species reflects their biogeographic affinities and that coexistence is
possible through pre-recruitment effects that limit the vertical distribution of P. perna and post-recruitment effects that limit M. galloprovincialis. 相似文献
598.
Katie E. Slocombe Tanja Kaller Laurel Turman Simon W. Townsend Sarah Papworth Paul Squibbs Klaus Zuberbühler 《Behavioral ecology and sociobiology》2010,64(12):1959-1966
Chimpanzees produce acoustically distinct calls when encountering food. Previous research on a number of species has indicated
that food-associated calls are relatively widespread in animal communication, and the production of these calls can be influenced
by both ecological and social factors. Here, we investigate the factors influencing the production of food-associated calls
in wild chimpanzees and examine whether male chimpanzees produce food-associated calls selectively in the presence of important
social partners. Male chimpanzees form stable long-term social relationships with each other, and these social bonds are vital
in enabling a range of cooperative activities, such as group hunting and territory defence. Our data show that males were
significantly more likely to produce food-associated calls if an important social partner was nearby, regardless of the size
of the audience or the presence of oestrus females. Call production was also mediated by the size of the food patch and by
whether or not the food could be monopolised. The presence of important social partners explained most of the variation in
male calling behaviour, indicating that food-associated calls are socially directed and serve a bonding function. 相似文献
599.
Grassroots watershed associations have formed as an avenue to facilitate public involvement in protecting watersheds. Growth in the number of watershed associations has created a need to evaluate whether their existence enhances environmental protection by local communities. In this research, environmental protection was measured by the number of watershed protection activities conducted and amount of funding directed towards protecting surface waters by non-profit, volunteer organizations. Regression models were utilized to examine the influence of population demographic and watershed characteristics variables to explain the formation of watershed associations along with watershed protection activities and funding. Regression results showed that the presence of watershed associations had positive impacts on both the number of activities and financial resources acquired. The results confirm that watershed associations enhance the ability of communities to obtain funding and to implement watershed protection actions. Thus, watershed associations serve as an effective institution for promoting environmental protection. 相似文献
600.
Todd S. Bridges Daniel Kovacs Matthew D. Wood Kelsie Baker Gordon Butte Sarah Thorne Igor Linkov 《The Environmentalist》2013,33(3):376-390
The potential impacts of climate change are varied and highly uncertain, and pose a significant challenge to agencies charged with managing environmental risks. This paper presents a comprehensive and structured Mental Modeling approach to elicit, organize and present relevant information from experts and stakeholders about the factors influencing environmental risk management in the face of climate change. We present and review an initiative undertaken by the United States Army Corps of Engineers (USACE) to characterize climate change challenges to USACE environmental risk management activities, and to identify gaps with respect to science, engineering, and organizational processes for addressing these challenges. By employing Mental Modeling, the research has characterized the influences of climate change on USACE environmental risk management, and aggregating recommendations from 28 experts. In addition, the study identifies the most important opportunities to improve organizational response to climate change, ranging from focused research and development of technical capabilities to broad paradigm shifts and systemic organizational improvements within the USACE environmental risk management programs. This study demonstrates that Mental Modeling is a useful tool for understanding complex problems, identifying gaps, and formulating strategies, and can be used by a multitude of organizations and agencies. 相似文献