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41.
Animal colour signals serve important functions in intraspecific interactions, including species recognition, mate choice and agonistic behaviour. An increasing interest concerns ultraviolet (UV) wavelengths, for instance studies on the effect of UV in mating decisions. More recently, some studies also established that UV signals affect intrasexual interactions. We studied the role of UV during aggressive encounters between male three-spined sticklebacks (Gasterosteus aculeatus), a species in which UV has an effect on female and male mate choice and shoaling behaviour. To that aim, we compared the aggressive response of a territorial male to male intruders, either seen in UV-including (UV+) or UV-lacking (UV-) conditions. Our prediction was that, if UV wavelengths are used in male-male competition, a territorial male should show less competitive behaviour towards an intruder representing a lower threat, i.e. the one presented without UV light. Male sticklebacks showed significantly lower levels of aggression towards male opponents lacking an UV component to their coloration than male opponents possessing this colour component. Discrimination was not influenced by a difference in brightness between the UV+ and UV- stimuli. Finally, we present some reflectance-spectrophotometrical data of two skin regions (cheek and abdomen) of the experimental males and analysed relationships between colorimetric variables, body variables and behaviour. Our study emphasises that UV visual cues are of importance in different communicational tasks in the three-spined stickleback. 相似文献
42.
Rick Overson Juergen Gadau Rebecca M. Clark Stephen C. Pratt Jennifer H. Fewell 《Behavioral ecology and sociobiology》2014,68(1):21-30
Research on the evolution of cooperative groups tends to explore the costs and benefits of cooperation, with less focus on the proximate behavioral changes necessary for the transition from solitary to cooperative living. However, understanding what proximate changes must occur, as well as those pre-conditions already in place, is critical to understanding the origins and evolution of sociality. The California harvester ant Pogonomyrmex californicus demonstrates population-level variation in colony founding over a close geographic range. In adjacent populations, queens either found nests as single individuals (haplometrosis) or form cooperative groups of nonrelatives (pleometrosis). We compared aggregation, aggression, and tolerance of queens from one pleometrotic and two haplometrotic populations during nest initiation, to determine which behaviors show an evolutionary shift and which are present at the transition to pleometrosis. Surprisingly, within-nest aggregative behavior was equally present among all populations. In nesting boxes with multiple available brood-rearing sites, both queen types readily formed and clustered around a single common brood pile, suggesting that innate attraction to brood (offspring) facilitates the transition to social aggregation. In contrast, queens from the three populations differed in their probabilities of attraction on the ground to nest sites occupied by other queens and in levels of aggression. Our results suggest that some key behavioral mechanisms facilitating cooperation in P. californicus are in place prior to the evolution of pleometrosis and that the switch from aggression to tolerance is critical for the evolution of stable cooperative associations. 相似文献
43.
Differences in sensitivity to the fungal pathogen Batrachochytrium dendrobatidis among amphibian populations
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Paul W. Bradley Stephanie S. Gervasi Jessica Hua Rickey D. Cothran Rick A. Relyea Deanna H. Olson Andrew R. Blaustein 《Conservation biology》2015,29(5):1347-1356
Contributing to the worldwide biodiversity crisis are emerging infectious diseases, which can lead to extirpations and extinctions of hosts. For example, the infectious fungal pathogen Batrachochytrium dendrobatidis (Bd) is associated with worldwide amphibian population declines and extinctions. Sensitivity to Bd varies with species, season, and life stage. However, there is little information on whether sensitivity to Bd differs among populations, which is essential for understanding Bd‐infection dynamics and for formulating conservation strategies. We experimentally investigated intraspecific differences in host sensitivity to Bd across 10 populations of wood frogs (Lithobates sylvaticus) raised from eggs to metamorphosis. We exposed the post‐metamorphic wood frogs to Bd and monitored survival for 30 days under controlled laboratory conditions. Populations differed in overall survival and mortality rate. Infection load also differed among populations but was not correlated with population differences in risk of mortality. Such population‐level variation in sensitivity to Bd may result in reservoir populations that may be a source for the transmission of Bd to other sensitive populations or species. Alternatively, remnant populations that are less sensitive to Bd could serve as sources for recolonization after epidemic events. 相似文献
44.
Allison Rick VandeVoort Ryan Tappero Yuji Arai 《Environmental science and pollution research international》2014,21(13):7828-7837
Residence time effects on phase transformation of silver nanoparticles (AgNPs) (15–50 nm, with and without polyvinylpyrrolidone (PVP) coating) were investigated in reducing soils using experimental geochemistry and synchrotron-based x-ray techniques. After 30 days of anaerobic incubation, a substantial fraction of PVP-coated AgNPs (15 nm) were transformed into Ag2S and or humic acid (HA) complexed Ag(I), whereas only the HA fraction was dominant in uncoated AgNPs (50 nm). Several investigations recently reported that sulfidation of AgNPs to Ag2S was the predominant mechanism controlling the fate of AgNP in soil–water environments. However, this investigation showed each AgNP underwent particle-specific chemical transformations to different end compounds after 30 days. Considering the small contribution of Ag(I) dissolution from all AgNPs (less than 5 %), we concluded that changes in solid-state chemical speciation of sorbed AgNPs was promoted by particle-specific interactions of NPs in soil chemical constituents, suggesting a critical role of soil absorbents in predicting the fate of AgNPs in terrestrial environments. 相似文献
45.
Bustard CJ Durham M Lindsey C Starns T Baldrey K Martin C Schlager R Sjostrom S Slye R Renninger S Monroe L Miller R Chang R 《Journal of the Air & Waste Management Association (1995)》2002,52(8):918-926
The overall objective of this project was to determine the cost and impacts of Hg control using sorbent injection into a Compact Hybrid Particulate Collector (COHPAC) at Alabama Power's Gaston Unit 3. This test is part of a program funded by the U.S. Department of Energy's National Energy Technology Laboratory (NETL) to obtain the necessary information to assess the costs of controlling Hg from coal-fired utility plants that do not have scrubbers for SO2 control. The economics will be developed based on various levels of Hg control. Gaston Unit 3 was chosen for testing because COHPAC represents a cost-effective retrofit option for utilities with existing electrostatic precipitators (ESPs). COHPAC is an EPRI-patented concept that places a high air-to-cloth ratio baghouse downstream of an existing ESP to improve overall particulate collection efficiency. Activated carbons were injected upstream of COHPAC and downstream of the ESP to obtain performance and operational data. Results were very encouraging, with up to 90% removal of Hg for short operating periods using powdered activated carbon (PAC). During the long-term tests, an average Hg removal efficiency of 78% was measured. The PAC injection rate for the long-term tests was chosen to maintain COHPAC cleaning frequency at less than 1.5 pulses/bag/hr. 相似文献
46.
The multiphase optimization strategy (MOST) and the sequential multiple assignment randomized trial (SMART): two novel evaluation methods for developing optimal training programs
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Current methodologies in training evaluation studies largely employ a single method entitled random confirmatory trials, prompting several concerns. First, practitioners and researchers often analyze the effectiveness of their entire omnibus training, rather than the individual elements or identifiable components of the training program. This slows the testing of theory and development of optimal training programs. Second, a common training is typically administered to all employees within an organization or workgroup; however, certain factors may cause individualized training to be more effective. Given these concerns, the current paper presents two training evaluation methodologies to overcome these problems: the multiphase optimization strategy and sequential multiple assignment randomized trials. The multiphase optimization strategy is a method to evaluate a standard training, which emphasizes the importance of a multi‐stage training evaluation process to analyze individual training elements. In contrast, sequential multiple assignment randomized trial is used to evaluate an adaptive training that varies over time and/or trainees. These methodologies jointly overcome the problems noted earlier, and they can be integrated to address several of the key challenges facing training researchers and practitioners. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
47.
48.
Numerous fishes possess UV vision and show UV patterns, which often play a role in social communication, especially during
courtship. UV light is scattered strongly in water and thus might be used for intra-specific close-range communication without
being detected by predators. In addition to the red-belly colouration and blue-coloured iris, male three-spined sticklebacks
possess UV reflectance on their skin, and females prefer males presented with UV light rather than without. To investigate
whether UV also influences male visual preference for females in this species, we used a dichotomous mate choice design in
which one female could be viewed by a male in two visual conditions. Courting male sticklebacks preferred females that were
presented in full-spectrum conditions including UV to the same females presented in conditions lacking this light component.
Furthermore, control trials with neutral-density filters indicated that male preference in the UV treatment was not affected
by a difference in achromatic brightness between the UV+ and UV− stimuli. Reflectance measurements of gravid females suggest
an enhanced UV contrast between the dark bar pattern, which is characteristic of gravid females, and silvery body parts. 相似文献
49.
Male boreal toads (Bufo boreas) are thought to return to the breeding site every year but, if absent in a particular year, will be more likely to return the following year. Using Pollock's robust design we estimated temporary emigration (the probability a male toad is absent from a breeding site in a given year) at three locations in Colorado, USA: two in Rocky Mountain National Park and one in Chaffee County. We present data that suggest that not all male toads return to the breeding site every year. Our analyses indicate that temporary emigration varies by site and time (for example, from 1992 to 1998, the probability of temporary emigration ranged from 10% to 29% and from 3% to 95% at Lost Lake and Kettle Tarn, respectively). Although the results provide weak evidence that males are more likely to return after a year's hiatus, a general pattern of state-dependent temporary emigration was not supported. We also hypothesized relationships between temporary emigration and a number of weather variables. While some competitive models included weather covariates, imprecise and variable estimates of the effects of these covariates precluded fully defining their impact on temporary emigration. 相似文献
50.
Edgerton ES Hartsell BE Saylor RD Jansen JJ Hansen DA Hidy GM 《Journal of the Air & Waste Management Association (1995)》2006,56(9):1325-1341
Deployment of continuous analyzers in the Southeastern Aerosol Research and Characterization Study (SEARCH) network began in 1998 and continues today as new technologies are developed. Measurement of fine particulate matter (PM2.5) mass is performed using a dried, 30 degrees C tapered element oscillating microbalance (TEOM). TEOM measurements are complemented by observations of light scattering by nephelometry. Measurements of major constituents include: (1) SO4(2-) via reduction to SO2; (2) NH4+ and NO3- via respective catalytic oxidation and reduction to NO, (3) black carbon (BC) by optical absorption, (4) total carbon by combustion to CO2, and (5) organic carbon by difference between the latter two measurements. Several illustrative examples of continuous data from the SEARCH network are presented. A distinctive composite annual average diurnal pattern is observed for PM2.5 mass, nitrate, and BC, likely indicating the influence of traffic-related emissions, growth, and break up of the boundary layer and formation of ammonium nitrate. Examination of PM2.5 components indicates the need to better understand the continuous composition of the unmeasured "other" category, because it contributes a significant fraction to total mass during periods of high PM2.5 loading. Selected episodes are presented to illustrate applications of SEARCH data. An SO2 conversion rate of 0.2%/hr is derived from an observation of a plume from a coal-fired power plant during early spring, and the importance of local, rural sources of NH3 to the formation of ammonium nitrate in particulate matter (PM) is demonstrated. 相似文献