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1.
Darryl T. Gwynne Winston J. Bailey Amanda Annells 《Behavioral ecology and sociobiology》1998,42(3):157-162
In katydids such as Kawanaphilanartee, a female bias in the operational sex ratio (OSR) results in female competition for mates and male choice of mates. Previous
work showed that the excess of sexually active females occurs when food availability is low, in part because less food increases
the propensity of females to mate as they forage for the large edible spermatophores produced by males. In this study with
K.nartee, a pollen-feeding species, we estimate natural variation in numbers of sexually active males and females by assessing male
calling activity and the propensity of females to respond to experimental calling males. We found an excess of sexually active
males at a site with many flowers and an excess of sexually active females at a site with few flowers about 900 m away. Between-site
differences in gut masses of calling males were consistent with the hypothesis that pollen availability controls OSR. Finally,
at a third site where flowers were at first scarce, we found that the initial excess in sexually active females changed to
an excess of sexually active males after a clump of grass-trees flowered. The mean gut mass of all sampled males from this
site increased after flowering. The large variation in OSR that we document for K. nartee highlights the importance of identifying the appropriate spatial and temporal scales over which OSRs are measured in studies
of factors controlling sexual selection.
Received: 13 May 1997 / Accepted after revision: 27 October 1997 相似文献
2.
Darryl Randerson 《Journal of the Air & Waste Management Association (1995)》2013,63(8):546-548
Two spectroradiometer measurements are presented to illustrate differences in the spectrum of sunlight in the 0.45–0.7 μ band. Only two spectral observations are presented, one in an apparently clean cloud-free air mass, the other under a heavily polluted air mass. Both observations were taken near Houston, Texas, on 12 November 1968 at about 1800 GMT. A 23% loss in the intensity of light is attributed to attenuation by pollution in the atmosphere. 相似文献
3.
Claudia Ursprung Michelle den Hollander Darryl T. Gwynne 《Behavioral ecology and sociobiology》2009,63(6):781-788
Female seed beetles, Callosobruchus maculatus, mate multiply even though association with males and copulations carry costs, such as injury to the genital tract. Multiple
mating (polyandry) may, however, offset these costs through the acquisition of food and water, two material benefits hypothesized
to be obtained from the large ejaculates produced by males. The material benefits hypothesis can be tested by increasing female
access to nutrients and water, with the prediction that female mating frequency will decrease as copulation is no longer required
to derive these materials. Females were given water, 5% sugar–water or baker’s yeast, and were compared with females deprived
of these. We presented females with virgin males daily for 8 days and recorded female mating frequency, survivorship, and
fecundity. Females provided with water and sugar–water decreased mating frequency. Thus, water, rather than nutrients in the
ejaculate, appears to be important to females of this species. In addition, both life span and fecundity were extended for
females in the sugar–water and water treatments. Since water is scarce in the arid environment in which this species is found,
we conclude that polyandry provides material benefits to females that may offset some of the costs of associating with males. 相似文献
4.
There has been recent concern regarding the possibility of antibiotics entering the aquatic food chain and impacting human consumers. This work reports experimental results of the bioconcentration of the antibiotic oxytetracycline (OTC) by the Asian watermeal plant (Wolffia globosa Hartog & Plas) and bioaccumulation of OTC in watermeal and water by the seven-striped carp (Probarbus jullieni). They show, for the first time, the extent to which OTC is able to transfer from water to plant to fish and enter the food chain. The mean bioconcentration factor (dry weight basis) with watermeal was 1.28 × 103 L kg−1. Separate experiments were undertaken to characterize accumulation of OTC by carp from water and watermeal. These showed the latter pathway to be dominant under the conditions employed. The bioconcentration and biomagnification factors for these processes were 1.75 L kg−1 and 2 × 10−4 kg g−1 respectively. Using an aqueous concentration range of 0.34–3.0 μg L−1, hazard quotients for human consumption of contaminated fish of 1.3 × 10−2 to 1.15 × 10−1 were derived. 相似文献
5.
Sampling design trade-offs in occupancy studies with imperfect detection: examples and software. 总被引:2,自引:0,他引:2
Larissa L Bailey James E Hines James D Nichols Darryl I MacKenzie 《Ecological applications》2007,17(1):281-290
Researchers have used occupancy, or probability of occupancy, as a response or state variable in a variety of studies (e.g., habitat modeling), and occupancy is increasingly favored by numerous state, federal, and international agencies engaged in monitoring programs. Recent advances in estimation methods have emphasized that reliable inferences can be made from these types of studies if detection and occupancy probabilities are simultaneously estimated. The need for temporal replication at sampled sites to estimate detection probability creates a trade-off between spatial replication (number of sample sites distributed within the area of interest/inference) and temporal replication (number of repeated surveys at each site). Here, we discuss a suite of questions commonly encountered during the design phase of occupancy studies, and we describe software (program GENPRES) developed to allow investigators to easily explore design trade-offs focused on particularities of their study system and sampling limitations. We illustrate the utility of program GENPRES using an amphibian example from Greater Yellowstone National Park, U.S.A. 相似文献
6.
Passive air sampling theory for semivolatile organic compounds 总被引:2,自引:0,他引:2
The mathematical modelling underlying passive air sampling theory can be based on mass transfer coefficients or rate constants. Generally, these models have not been inter-related. Starting with basic models, the exchange of chemicals between the gaseous phase and the sampler is developed using mass transfer coefficients and rate constants. Importantly, the inter-relationships between the approaches are demonstrated by relating uptake rate constants and loss rate constants to mass transfer coefficients when either sampler-side or air-side resistance is dominating chemical exchange. The influence of sampler area and sampler volume on chemical exchange is discussed in general terms and as they relate to frequently used parameters such as sampling rates and time to equilibrium. Where air-side or sampler-side resistance dominates, an increase in the surface area of the sampler will increase sampling rates. Sampling rates are not related to the sampler/air partition coefficient (K(SV)) when air-side resistance dominates and increase with K(SV) when sampler-side resistance dominates. 相似文献
7.
Romyen S Hawker D Karnchanasest B 《Journal of environmental science and health. Part. B》2007,42(8):869-875
Sorption and leaching of the organophosphate (OP) pesticides chlorpyrifos, profenofos, methyl parathion and malathion were investigated with four different types of biomass: coconut husk, rice husk, peat moss and peanut shell. Organic carbon contents of the biomass were in the range of 35.4-45.4%. Sorption studies were carried out by the batch (equilibrium) method at 4 different OP spike concentrations and at pH 3-7. Sorption isotherms conformed to a linear Freundlich equation and the Freundlich constant or sorption coefficient (KD) confirmed that biomass organic carbon content was the principal sorbent factor affecting OP sorption. For a given sorbent, correlation of the extent of sorption with sorbate chemical properties was examined. Column leaching experiments involving different masses of coconut husk and peanut shell pre-spiked with OPs at the level equivalent to actual spraying concentrations in some Thai tangerine orchards were conducted. These experiments included repeated spikings and leaching. A water flow rate of 20 mL min(-1) was employed corresponding to the current average watering regime. Retardation and biodegradation with these sorbents were also examined. 相似文献
8.
Darryl J. Keith Dave Colton Harry Louft John Lindsay Lance Stewart 《Environmental monitoring and assessment》1999,54(3):259-282
The Underwater Radiation Spectral Identification System (URSIS) is a portable spectrometer used for the in situ detection of radioactivity in the marine environment. This paper reports on the first time application of this technology to assess, in a preliminary manner, the potential radiation threat to the public and environment at an aquatic disposal site – the Massachusetts Bay Industrial Waste Site (IWS). Utilizing the meneuvering capabilities of ROV and manned submersible vehicles, the URSIS was successfully positioned close (5–10 cm) to waste containers for a period sufficient to detect, in real time, the presence of radioactive materials. Spectral data from 45 individual targets indicated that the radionuclides present in sediments which draped or partially buried waste containers were consistent with natural background concentrations. No man-made radionuclides were detected at any of the target or background measurement locations. These data support the conclusion that low-level radiation does not pose an imminent and widespread human health or ecological threat in Massachusetts Bay. 相似文献
9.
10.
We have determined the activity of alkaline phosphatase in chorionic villous tissue obtained in the first trimester of pregnancy, in order to obtain the normal range of values as a prerequisite for application to the prenatal diagnosis of the rare bone disease hypophosphatasia. The activities found were a combination of intestinal and liver/bone/kidney types; traces of placental type were present in only one sample. 相似文献