摘要:

Experimental studies of food competition were performed in lowland forest of French Guiana by controlled introduction and removal of a small number of African honey bee colonies, totaling 100 000—150 000 bees. Trends in brood production and food storage by observations colonies of native social bees, Melipona favosa and M. fulva, were described with linear stochastic statistical models. Data were taken after the introduction of honey bee colonies, and the models were used to construct falsifiable hypotheses that would suggest whether the honey bees disrupted colony growth and resource harvest of native species. During a 1—mo introduction of honey bees in the wet season, when floral resources were at low abundance, time—series intervention analyses showed that African Apis had no significant effect on native bee colonies. Repeated—measures ANOVA also showed no treatment effect on bee colonies, and removal of 5—10 honey bee colonies had no effect on brood dynamics and food storage of four conspecific colonies. All colonies foraged during experiments, yet no competition was recorded. Since the three species are diet generalists and share many of the same resources, competition at flowers was not disproved, although any cumulative effects were negligible. Linear, stochastic integrated autoregression/moving average (ARIMA) models were useful in removing statistical dependence in data series and allowing hypothesis tests, but intracolony variables showed seasonal decline that prevented introduction of deterministic components that would have improved some models. Perturbation of social tropical bee communities by colonizing African Apis is unlikely to become evident within a short time or at relatively low honey bee colony density.

ISSN:0012-9658    

DOI:10.2307/1937803

出版商:Ecological Society of America    

年代:1983

数据来源: WILEY

摘要:

The aerobic and anaerobic energetic contributions to courtship and aggression between males were measured in the plethodontid salamander Desmognathus ochrophaeus in the laboratory. Average rate of oxygen consumption and average lactate content were increased significantly above resting levels during both courtship (O2: +0.029 mL°g—1°h—1; lactate: +0.058 mg/g) and aggression (O2: +0.040 mL°g—1°h—1; lactate: +0.172 mg/g). However, these are rather small increments, representing rises of only 38—56% in oxygen consumption and only 8—23% of anaerobic capacity. The cost of a courtship bout is estimated to be 2.70 J/courting pair and is derived 90% aerobically. This value represents °1% of the daily ingested energy and secondary productivity for this species, based on estimates in a previous study. It thus seems unlikely that the behavior patterns of courtship or aggression in this species are subject to energetic limtations.

ISSN:0012-9658    

DOI:10.2307/1937804

出版商:Ecological Society of America    

年代:1983

数据来源: WILEY

摘要:

Hypothesis attempting to explain structure in desert rodent assemblies have emerged primarily from studies dealing with heteromyid interactions. Little attention has been given to the cricetid elements in the community, despite their often high densities and year—round activity in close association with heteromyid species. This study extends the understanding of desert rodent assembly dynamics by examining interactions in microhabitat use between Dipodomys ordii (Heteromyidae) and Onychomys leucogaster (Cricetidae). Research was designed to test the hypothesis: in a two species (experimental) enclosure, microhabitat use by each species will not differ from that in one species (control) enclosures. Results indicate that D. ordii shifts microhabitat use when co—occurring with O. leucogaster, while the reverse does not occur. This outcome shows that interactions are operating between these two species. Further, studies and aimed at determining presumed structure among desert rodent species may be lacking information on significant nonheteromyid elements of the community.

ISSN:0012-9658    

DOI:10.2307/1937805

出版商:Ecological Society of America    

年代:1983

数据来源: WILEY

摘要:

Operative environmental temperatures (Te, an index of the thermal environment) were measured for basking Pseudemys scripta in South Carolina. Operative environmental temperatures were good predictors of the basking behavior of P. scripta. Turtles in this study generally did not bask unless Tewas 28°C (preferred body temperature) or higher. This demonstrated that basking was not a random behavior in respect to Te, and implicated thermoregulation as a major factor eliciting basking behavior. Operative environmental temperature was positively related to short—wave and total solar radition as well as to air and substrate temperature. Substrate temperature was the best single predictor of Te. A multiple regression equation (Te= 0.005R + 0.103Ta— 1.16 log V + 0.932Ts— 2.54, r2= .90, where R = total radiation in watts per square metre, Ta= air temperature in degrees Celsius, V = wind speed in metres per second, and Ts= substrate temperature in degrees Celsius) defines the relationship of Teto microclimate variables. Movement of the sun through the day results in spatial variation in Te's available to turtles and influences their location and basking behavior.

ISSN:0012-9658    

DOI:10.2307/1937806

出版商:Ecological Society of America    

年代:1983

数据来源: WILEY

摘要:

This is a study of the transmission ecology of an acanthocephalan parasite (Plagiorhynchus cylindraceus) in its natural intermediate host (the isopod Armadillidium vulgare) and definitive host the (the Starling, Sturnus vulgaris). It is the first study to demonstrate in both the laboratory and the field that parasites may produce behaviorally dimorphic prey populations with respect to definitive host foraging patterns. Differences in the prevalence of such parasites could influence the outcomes of a variety of field studies involving foraging because encounter rates in such situations may not uniformly reflect prey abundances. My experiments showed that infected A. vulgare do not behave like uninfected conspecifics. In laboratory tests, infected animals were found more frequently in less humid areas, on light—colored substrate, and in unsheltered areas. Infected females rested less often and moved farther. They did not develop ovaries and did not grow as rapidly as control females. Nestling Starlings in the field had a higher P. cylindraceus prevalence than that expected if parents had foraged on isopods without respect to infection. In the laboratory, adult Starlings consumed more infected than uninfected isopods when presented with the same number of each. This foragingpreference is probably because of increased encounters with infected isopods, which apparently frequent more exposed areas than do uninfected conspecifics.

ISSN:0012-9658    

DOI:10.2307/1937807

出版商:Ecological Society of America    

年代:1983

数据来源: WILEY

摘要:

Larvae of an unidentified bruchid beetle develop within and kill seeds of the palm Scheelea zonensis. Only one larva can develop per seed. Hence, a selective advantage should accrue to females bruchids that oviposit on previously unattacked (pristine) fruit. On Barro Colorado Island, Panama, I performed experiments to test the following hypotheses. (1) H0: female bruchids do not distinguish between previously attacked and pristine fruit, and (2) H0: female bruchids oviposit at random among Scheelea fruit. Both null hypotheses were rejected. Female bruchids oviposit more frequently on pristine fruit, and female bruchids disperse their eggs uniformly among Scheelea fruit. Such sophisticated seed predators might search large areas of pristine seeds. As a result, seed—predation rates may fall slowly with distance from the parent palm. To test this hypothesis. I exposed Scheelea fruit at distances of 1, 8, 16 and 100 m from the nearest fruiting palm. Within 16 m, bruchid attack rates were uniformly high. However, at 100 m there was a significant decline. Other studies have found declines in seed predation rates, but only over similarly large distances. This has important implications for the mechanism by which density—dependent seed predation might contribute to the coexistence of tropical trees.

ISSN:0012-9658    

DOI:10.2307/1937808

出版商:Ecological Society of America    

年代:1983

数据来源: WILEY

摘要:

We tested for the presence and importance of nonlinear relationships among bird species abundances and vegetation characteristics of the lower Colorado River valley. We transformed vegetation variables into polynomials and then ran multiple regressions, with bird densities as the dependent variables. Polynomial variables were selected in 36% of first steps and 45% of second steps in the regressions. In a significant number of cases there was a response to a polynomial variable but not to the original linear variable. Importance of curvilinear responses varied among bird species. This method offers a more comprehensive examination of responses to envirnomental gradients because unimodal and some skewed relationships can be detected.

ISSN:0012-9658    

DOI:10.2307/1937809

出版商:Ecological Society of America    

年代:1983

数据来源: WILEY

摘要:

As host—plant density increases, the oviposition rate of Battus philenor butterflies increases, then levels off. By contrast, alighting rates continues to increase with host density approximately linearly. The leveling off of oviposition rates is caused by a decline in the probability that a female will oviposit once she alights on a plant. Evidence is presented indicating that these phenomena are due to an increase in female selectivity as plant density increases, rather than to a limit on oviposition rate imposed by the rate of egg maturation. This type of behavioral response to host density is a mechanism that can explain in part the tendency of many herbivorous insects to aggregate to a greater degree in low—density than in high—density stands of host plants.

ISSN:0012-9658    

DOI:10.2307/1937810

出版商:Ecological Society of America    

年代:1983

数据来源: WILEY

摘要:

The effect of phytophagous beetles on plant succession in an old—field community in southeastern Ontario was investigated over a 5—yr period. An experimental comparison of insecticide treated and untreated plots indicates that grazing by Trirhabda spp. on the goldenrod Solidago canadensis resulted in a reduction in precent cover of this species (from 40—70% to °1%), and a significant increase in percent cover of a number of earlier stage successional species.

ISSN:0012-9658    

DOI:10.2307/1937811

出版商:Ecological Society of America    

年代:1983

数据来源: WILEY

摘要:

The effects of low—level consumption by canopy arthropods on foliage nutrient content, canopy leachates (throughfall), and biomass of 4—yr—old black locust (Robinia pseudoacacia) and red maple (Acer rubrum) were studied in the southern Appalachians of North Carolina. A carbaryl insecticide was used to reduce foliage consumption from °10 to °2% in black locust and from °4 to °1% in red maple. Phosphorus concentrations in untreated black locust foliage were significantly lower than those of insecticide—treated foliage early in summer, but equalled concentrations of treated foliage by late summer. Potassium concentrations in untreated red maple foliage were significantly reduced during late summer; calcium concentrations in untreated red maple foliage were significantly higher later in the summer. Potassium in throughfall from black locus trees (amount of K collected below the canopy minus bulk precipitation inputs) increases from 5.7 kg/ha for insecticide—protected trees to 9.8 kg/ha for unprotected trees (P<.05). Potassium lossesw from unprotected red maple also increased. Black locust lost 0.3 kg/ha of sulfate—S from untreated trees, but adsorbed 0.4 kg/ha of sulfate—S in insecticide—treated trees (P<.05). Total biomass production (net primary production per kilogram of preseason biomass) was unaffected by the low levels of herbivory observed here. Such nominal herbivory did not stimulate biomass and nutrient accretion by these tree species but did increase the cycling of K and perhaps other elements within these systems.

ISSN:0012-9658    

DOI:10.2307/1937812

出版商:Ecological Society of America    

年代:1983

数据来源: WILEY