排序方式: 共有38条查询结果,搜索用时 15 毫秒
31.
D. M. Pratt 《Marine Biology》1974,27(1):37-45
Urosalpinx cinerea (Say), accustomed to feeding on Balanus balanoides, were strongly attracted in a choice chamber by the effluents of B. balanoides and B. eburneus, were indifferent to the effluents of Crassostrea virginica, Crepidula fornicata and Mytilus edulis, and responded negatively to the effluent of their own species. Oyster drills from a population feeding on Crassostrea virginica were attracted to oyster effluent; when these snails were offered a choice between Crassostrea virginica and B. balanoides effluents, they responded in equal numbers to the two effluents. Concentrations of NH4Cl-ammonia in the range 18.2 to 73.3 mol did not attract the snails, and their responses to animal effluents were not correlated with the ammonia and amino-acid concentrations of the effluents, which ranged from 11.8 to 21.0 mol. It is argued that these results deny ammonia the role of a nonspecific distance attractant. Confined separately with various potential prey species, Urosalpinx drilled Balanus balanoides, B. eburneus, Crassostrea virginica, Crepidula fornicata, C. plana, Mercenaria mercenaria, Modiolus demissus, Mya arenaria, Mytilus edulis, Spisula solidissima, and Yoldia limatula, but not Anomia simplex. The prey species that were the least attractive in running water were generally rendered attractive and subject to attack in standing water. Freshly shucked Crepidula fornicata shells were scarcely drilled unless continuously perfused by C. fornicata effluent, and then only in small numbers. Altering the texture of living C. fornicata shells by wrapping them in nylon netting, by polishing, or by roughening, did not make them immune to drilling. Oyster drills in contact with C. fornicata attacked only if they received the effluent of the living prey, proving that tactile stimuli alone are not adequate to induce drilling. 相似文献
32.
A modelling framework for understanding social insect foraging 总被引:1,自引:0,他引:1
33.
Stephen C. Pratt 《Behavioral ecology and sociobiology》1999,46(1):30-42
Honeybee colonies, like organisms, should exhibit optimal design in their temporal pattern of resource allocation to somatic
structures. A vital colony structure is the comb which stores honey for overwinter survival. However, the timing of comb construction
poses a dilemma to a colony attempting to maximize its honey reserves. On the one hand, plenty of empty comb is needed for
efficient exploitation of temporally unpredictable flower blooms. On the other hand, because comb is made from energetically
expensive wax, its construction too early or in excessive amounts will reduce the amount of honey available for winter thermoregulation
and brood-rearing. A dynamic optimization model concludes that colonies should add new comb only when they have filled their
old comb with food and brood above a threshold level. The threshold increases with time until, at the end of the season, building
is never an optimal behavior. The temporal pattern of construction predicted by the model – pulses of building coincident
with periods of nectar intake and comb fullness – matches that seen in an actual colony observed over the course of an entire
foraging season. When nectar sources are rich but temporally clumped, the model also predicts that bees should be sensitive
to nectar intake, employing much higher thresholds on days when nectar is not available than on days when it is. Even under
poorer and more dispersed nectar regimes, little fitness cost is paid by colonies replacing the optimal strategy with a simpler
rule of thumb calling for new construction only when two conditions are met: (1) a fullness threshold has been exceeded, and
(2) nectar is currently being collected. Experiments demonstrate that colonies do in fact use such a rule of thumb to control
the onset of construction. However, once they have begun building, the bees continue as long as nectar collection persists,
regardless of changes in comb fullness. Thus the onset and duration of comb-building bouts appear to be under partially independent
control.
Received: 30 October 1998 / Received in revised form: 14 December 1998 / Accepted: 16 January 1999 相似文献
34.
ABSTRACT: The introduction of genetically altered microorganisms into natural ecosystems presents fundamentally new problems in risk assessment and ecological effect evaluation. Novel microorganisms, produced by any of several new methods, have the ability to survive and reproduce in the environment. Since most of these organisms are bacteria, they have the potential to interfere with natural processes, displace natural populations, infect new hosts, move between ecosystems, and cause far-reaching ecological disturbanes. This paper reviews currently available methods in ecological research that might be used in evaluating the ecological effects of releasing genetically altered microorganisms. Both structural and functional evaluations are critically reviewed. Microcosm, mesocosm, and field tests should provide valuable predictions concerning the potential ecological impact of genetically altered organisms. Ecosystem assessments will also be useful in post-release studies such as those currently used to evaluate toxic impacts. The present problem does not require the development of new testing methods but rather the creation of adequate predictive models (both conceptual and systems-based) to predict the potential for adverse effect of genetically altered organisms. 相似文献
35.
Efficiency and regulation of recruitment during colony emigration by the ant Temnothorax curvispinosus 总被引:1,自引:1,他引:0
Stephen C. Pratt 《Behavioral ecology and sociobiology》2008,62(8):1369-1376
Recruitment helps insect societies by bringing individuals to places where work needs to be done, but it also imposes energetic
and opportunity costs. The net effect depends both on recruitment efficiency and on the ease with which insects can find work
sites on their own. This study examined both of these factors for colony emigration by the ant Temnothorax curvispinosus. Emigrations were organized by a corps of active ants who transported the rest of the colony. These active ants either found
new sites independently or followed tandem runs led by successful scouts. Although most tandem runs broke apart before reaching
their target, even lost followers found the new site faster than did unguided searchers. When the new site was near the old
nest, tandem runs were rare and summoned only a small proportion of the transporter corps. When the new site was instead distant
and inconspicuous, tandem runs were common and brought roughly one third of the transporters. This pattern likely results
from the quorum rule used by individual scouts to decide when to switch from tandem runs to transports. By monitoring how
many nestmates have already found the nest, the ants ensure that the costs of recruitment are born only when necessary. 相似文献
36.
37.
George M. Williams Thomas H. Pratt 《Journal of Loss Prevention in the Process Industries》1990,3(4):381-385
In the assessment of electrostatic hazards in the process industries, a great deal of emphasis has been placed on the determination of energies in spark discharges. There are, however, other electrostatic discharge phenomena where this approach has severe limitations. The purpose of this paper is to describe the state-of-the-art with respect to electrostatic discharges in gases (air). An in depth review of the literature has been made, and the various types of discharges are tabulated and discussed. 相似文献
38.
Maki BE Sibley KM Jaglal SB Bayley M Brooks D Fernie GR Flint AJ Gage W Liu BA McIlroy WE Mihailidis A Perry SD Popovic MR Pratt J Zettel JL 《Journal of Safety Research》2011,42(6):473-485