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541.
542.
543.
Selective predation can be an important force driving the evolution of organisms. In particular, sex-biased predation is expected to have implications for sexual selection, sex allocation and population dynamics. In this study, we analysed sex differences in the predation of the western green lizard (Lacerta bilineata) by the Eurasian kestrel (Falco tinnunculus) during the reproductive season. In addition, we investigated whether the rate of predation differed during the 8-year study period and among the three habitats studied. We collected lizard remains from nest boxes of kestrels. Freshly killed lizards were sexed by visual inspection, whilst the sex of head remains was assigned by analysing the cephalic scale morphology using geometric morphometrics. Our results show that the risk of being predated by a kestrel in our population was overall about 3.55 times higher for males than for females. To our knowledge this is the first study showing a male-biased predation in a lizard species. The selective predation of males was consistent between years over the 8-year study period (1999-2006) and also consistent between the three types of kestrel hunting habitat. Overall predation rates on lizards differed between habitats, depending on the year. We propose that the observed sex-biased predation is mainly due to sex differences in lizard behaviour. 相似文献
544.
The great barracuda (Sphyraena barracuda) is a widespread, ecologically and socioeconomically important coastal fish, yet very little is known about its larvae. We
examined spawning and larval ecology of Western Atlantic sphyraenids using monthly ichthyoplankton samples collected over
2 years along a transect spanning the east–west axis of the Straits of Florida (SOF). Samples were dominated by the great
barracuda (92.8%) and sennets (Sphyraena borealis and Sphyraena picudilla; 6.6%). While larval sennets and S. barracuda displayed similar vertical distributions (majority in upper 25 m), horizontal and temporal patterns of abundance suggested
a spatial and temporal species replacement between larval S. barracuda and sennets that tracks adult ecology. The diet of both taxa consisted largely of copepods, with inclusion of fish larvae
at 8 mm SL, and in S. barracuda alone, a switch in the wet season to exclusive piscivory by 12 mm SL (18 days post-hatch). A lack of piscivory in S. barracuda larvae captured in the dry season corresponded to slower larval growth than in the wet season. Larval growth was also related
to size-at-hatch and larval age such that larvae that were larger at hatch or larger (older) at capture grew faster at earlier
ages, suggesting faster larval growth, and indirectly larger hatch size, conveys a survival advantage. Unlike larval growth,
instantaneous mortality rate did not differ with season, and no lunar cyclic patterns in spawning output were identified.
Our results provide insight into the pelagic phase of sphyraenids and highlight the importance of both diet and hatch size
to the growth and survival of fish larvae in low latitude oceanic environments. 相似文献
545.
William J. O’Shea Peter A. Scheff 《Journal of the Air & Waste Management Association (1995)》2013,63(8):1020-1026
Increasing attention to the presence of atmospheric volatile organic compounds has focused interest on the sources and fate of organics in ambient air. The purpose of this study was to develop a chemical mass balance receptor model (CMB) to determine the contributions of major organic pollution source types to ambient pollution levels. Twenty mid-day ambient air samples were analyzed for the presence of volatile hydrocarbons by gas chromatographlc procedures. Based on these measurements, contributions from vehicles, gasoline vapor emissions, and petroleum refineries to ambient organic concentrations were estimated. For the receptor site studied, vehicles were the dominant source type and accounted for 60.8 percent of the organics evaluated. Contributions from refineries, gasoline vapor, and all other sources were 10.1, 11.1, and 17.9 percent, respectively. Validation of the predictions showed that the model is sensitive to the effect of overall upwind emissions. The CMB model was shown to produce reasonable predictive results for vehicles, gasoline vapor, and refinery contributions to ambient non-methane organic concentrations. 相似文献
546.
A carefully designed survey of medical waste management was undertaken in Dhaka, the capital city of Bangladesh. A range of sampling strategies and data gathering techniques were used. The data gathering techniques included observation, formal structured interview and informal dialogue. Sampling strategies included formal representative sampling for fixed populations and adaptive sampling for roaming populations was developed. Data were collected from healthcare establishments (HCEs) and other waste disposal operatives.Operatives dealing with waste were frequently found to be untrained, and without even a basic understanding of the hazards involved. Personal protective equipment was inadequate in most cases which led to frequent accidental injuries. No HCE was found to have adequate storage facilities for hazardous waste. Thus scavengers were able to gain access to items such as syringes and expired medicines, which they repackaged and resold. The lack of correctly controlled internal storage may be linked to the observation that employees at many HCEs offered contaminated items for sale to scavengers and recycling operatives. In many cases there was no attempt at segregation, but in some cases there was segregation at the point of use, but subsequent remixing with general waste, indicating a lack of management and education rather than a lack of will. In either case, hazardous waste was dumped in city corporation bins, and disposed of on general landfill sites. As well as exposing the waste to scavengers, this could potentially contaminate ground water, especially as the dumps were located in areas subject to frequent flooding. 相似文献
547.
548.
Kazuharu Ohashi Daniel D’Souza James D. Thomson 《Behavioral ecology and sociobiology》2010,64(5):891-897
Nectar-feeding animals have served as the subjects of many experimental studies and theoretical models of foraging. Their
willingness to visit artificial feeders renders many species amenable to controlled experiments using mechanical “flowers”
that replenish nectar automatically. However, the structural complexity of such feeders and the lack of a device for tracking
the movements of multiple individuals have limited our ability to ask some specific questions related to natural foraging
contexts, especially in competitive situations. To overcome such difficulties, we developed an experimental system for producing
computer records of multiple foragers harvesting from simple artificial flowers with known rates of nectar secretion, using
radio frequency identification (RFID) tags to identify individual animals. By using infrared detectors (light-emitting diodes
and phototransistors) to activate the RFID readers momentarily when needed, our system prevents the RFID chips from heating
up and disturbing the foraging behavior of focal animals. To demonstrate these advantages, we performed a preliminary experiment
with a captive colony of bumble bees, Bombus impatiens. In the experiment, two bees were tagged with RFID chips (2.5 × 2.5 mm, manufactured by Hitachi-Maxell, Ltd., Tokyo, Japan)
and allowed to forage on 16 artificial flowers arranged in a big flight cage. Using the resulting data set, we present details
of how the bees increased their travel speed between flowers, while decreasing the average nectar crop per flower, as they
gained experience. Our system provides a powerful tool to track the movement patterns, reward history, and long-term foraging
performance of individual foragers at large spatial scales. 相似文献
549.
A. A. Nikol’skii 《Russian Journal of Ecology》2008,39(7):530-536
With consideration of the data on soil temperature within the range of the Altai zokor Myospalax myospalax Laxmann (1773) published in the Handbook on the Climate of the Soviet Union, it has been shown that the actual temperature niche of this species is relatively narrow. Seasonal movements over the vertical
profile of the burrow allow zokors to avoid exposure to subzero temperatures. 相似文献
550.
Energy expenditures for reproduction in local populations of the pied flycatcher in the environs of the Middle Urals Copper Smelter (Revda, Sverdlovsk oblast) have been estimated on the basis of the results of long-term studies (1989?C2008). It is shown that the total energy expenditures per fledgling over the nesting period are 1.2 times higher than in the background area, which is explained by increased energy losses (by a factor of 4.1) resulting from partial mortality of the progeny (eggs or nestlings). Variation in the average energy ??cost?? of one fledgling in the heavily polluted zone is also higher, compared to the background area. Average energy expenditures per fledgling increase in years with cold weather, and the same is observed when the birds lay larger clutches. 相似文献