排序方式: 共有48条查询结果,搜索用时 15 毫秒
31.
Suzanne M. O’Regan Denis FlynnThomas C. Kelly Michael J.A. O’CallaghanAlexei V. Pokrovskii Dmitrii Rachinskii 《Ecological modelling》2012,224(1):54-64
The recent rapid growth of the woodpigeon population in the British Isles is a cause for concern for environmental managers. It is unclear what has driven their increase in abundance. Using a mathematical model, we explored two possible mechanisms, reduced intraspecific competition for food and increased reproductive success. We developed an age-structured hybrid model consisting of a system of ordinary differential equations that describes density-dependent mortality and a discrete component, which represents the birth-pulse. We investigated equilibrium population dynamics using our model. The two hypotheses predict contrasting population age profiles at equilibrium. We adapted the model to examine the impacts of control measures. We showed that an annual shooting season that follows the period of density-dependent mortality is the most effective control strategy because it simultaneously removes adult and juvenile woodpigeons. The model is a first step towards understanding the processes that influence the dynamics of woodpigeon populations. 相似文献
32.
Laboratory studies show that predatory cane toads (Bufo marinus) exhibit specialized toe-luring behavior that attracts smaller conspecifics, but field surveys of toad diet rarely record
cannibalism. Our data resolve this paradox, showing that cannibalism is common under specific ecological conditions. In the
wet–dry tropics of Australia, desiccation risk constrains recently metamorphosed toads to the edges of the natal pond. Juvenile
toads large enough to consume their smaller conspecifics switch to a primarily cannibalistic diet (67% of prey biomass in
stomachs of larger toads). Cannibalistic attack was triggered by prey movement, and (perhaps as an adaptive response to this
threat) small (edible-sized) toads were virtually immobile at night (when cannibals were active). Smaller metamorphs were
consumed more frequently than were larger conspecifics. The switch from insectivory to cannibalism reflects the high dry season
densities of small conspecifics (in turn, due to desiccation-imposed constraints to dispersal) and the scarcity of alternative
(insect) prey during dry weather. Our study pond (102 m in circumference) supported >400 juvenile toads, which consumed many
metamorphs over the course of our study. Toads appear to be low-quality food items for other toads; in laboratory trials,
juvenile toads that fed only on conspecifics grew less rapidly than those that ate an equivalent mass of insects. This effect
was not due to parotoid gland toxins per se. Thus, cane toads switch to intensive cannibalism only when seasonal precipitation
regimes increase encounter rates between large and small toads, while simultaneously reducing the availability of alternative
prey. 相似文献
33.
Despite abundant research on the consequences of perceived abusive supervision, less is known about how employees develop perceptions of supervisory abuse. Across two studies, we integrate classic and recent theoretical work on attributions to understand the causal explanations underlying employee perceptions of and reactions to abusive supervision. In the first study, we develop measures of internal, external, and relational attributions for perceived supervisor abuse. In the second study, we demonstrate that internal and external attributions are indirectly related to aggressive and citizenship behaviors through employees' perceptions of interactional justice. Theoretical and practical implications are also discussed. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
34.
Four populations of Anthoxanthum odoratum from North Wales, UK, were exposed to the following combinations of mean background and peak concentrations of ozone for 12 weeks in solardomes: LL (14.3 ppb, 18.9 ppb, respectively), LH (14.8 ppb, 52.3 ppb), HL (28.9 ppb, 35.7 ppb) and HH (30.5 ppb, 72.1 ppb). Elevated ozone rapidly induced premature senescence, with effect increasing in the order: LL < LH < HL < HH. By week 11, the LH and HL treatments had induced similar amounts of whole plant senescence even though the AOT4012 values (accumulated between 8am and 8pm) were very different at 10.6 ppm h and 4.1 ppm h, respectively. Overall, linear correlations between whole plant senescence were stronger for AOT0 than for AOT40. Intraspecific variation in the senescence response to the different profiles was observed after 11 weeks of exposure. Effects on growth and tillering were less pronounced than effects on senescence. 相似文献
35.
Lynne A. Isbell Jill D. Pruetz Truman P. Young 《Behavioral ecology and sociobiology》1998,42(2):123-133
The effect of food resources on behavior has been difficult to measure. Here we use animals themselves to describe “effective”
food abundance and distribution by comparing, relative to where individuals stopped to eat, movements of (1) adult females
living in a small group of vervet monkeys (Cercopithecus aethiops) with those living in a large group and (2) vervets and patas monkeys (Erythrocebus patas). Although females in the large vervet group travelled farther and stopped to eat more often than females in the small vervet
group, these differences resulted from foraging in Acacia drepanolobium habitat. In A. xanthophloea habitat, females in the large group travelled less far, travelled shorter distances between foods, and stopped as often as
females in the small group. Greater foraging costs of females in larger vervet groups may be offset by access to home ranges
of better quality. Compared to patas, vervets travelled shorter distances, moved shorter distances between food sites, stopped
less often, and had longer feeding bouts, suggesting that foods of vervets are denser and larger, overall, than foods of patas.
When vervets foraged in A. drepanolobium habitat, also the habitat of patas, their foraging behavior became more like that of patas. Vervets travelled farther, stopped
more often, and spent less time at food sites in A. drepanolobium habitat than in A. xanthophloea habitat, suggesting that foods are smaller and less usurpable in A. drepanolobium habitat. Distance between foods, a component of food distribution, did not increase, however. The critical variable underlying
usurpability of foods may be food site depletion time, a temporal measure.
Received: 14 March 1997 / Accepted after revision: 19 October 1997 相似文献
36.
Exaggerated male eye span influences contest outcome in stalk-eyed flies (Diopsidae) 总被引:3,自引:0,他引:3
Evolution of male weapons or status signals has been hypothesized to precede evolution of female mating preferences for those
traits. We used staged male fights among three species of Malaysian stalk-eyed flies (Diptera: Diopsidae) to determine if
elongated eye span, which is preferred by females in two sexually dimorphic species, influences contest outcome. Extreme sexual
dimorphism, with large males possessing longer eye span than females, is shared by Cyrtodiopsis whitei and C. dalmanni. In contrast, C. quinqueguttata exhibits a more ancestral condition – short, sexually monomorphic eye stalks. Videotape analysis of 20-min paired contests
revealed that males with larger eye span and body size won more fights in the dimorphic, but not monomorphic, species. To
determine if males from the dimorphic species use eye span directly to resolve contests, we competed male C. dalmanni from lines that had undergone artificial selection for 30 generations to increase or decrease eye span. We found that eye
span, independently of body size, determines contest outcome in selected-line males. Furthermore, in both dimorphic species,
the average encounter duration declined as the eye span difference between contestants increased, as expected if males use
eye span to assess opponent size. The number of encounters also increased with age in dimorphic, but not monomorphic, species.
Selected-line males did not differ from outbred males in either fight duration or number of encounters. We conclude that exaggerated
male eye stalks evolved to influence both competitive interactions and female mating preferences in these spectacular flies.
Received: 20 July 1998 / Received in revised form: 2 February 1999 / Accepted: 12 March 1999 相似文献
37.
Sibling aggression, hatching asynchrony, and nestling mortality in the black kite (Milvus migrans) 总被引:3,自引:0,他引:3
Javier Viñuela 《Behavioral ecology and sociobiology》1999,45(1):33-45
In siblicidal species, hatching asynchrony could act to reduce sibling rivalry or promote the death of last-hatched chicks.
The pattern of hatching asynchrony was experimentally altered in the black kite Milvus migrans. Hatching asynchrony in control broods was intermediate between those of experimentally synchronised and asynchronised broods.
Sibling aggression and wounds on the chicks were more commonly observed early in the nestling period and in synchronous nests.
Serious injuries were observed on last-hatched chicks in asynchronous nests, as were observations of intimidated or crushed
chicks. Sibling aggression was related to food abundance, but some chicks died at an early age in nests with abundant food
(cainism). Cainism was more commonly found in asynchronous nests. For species with facultative siblicide, moderate hatching
asynchrony could be a compromise between reducing sibling rivalry and avoiding large size differences between sibs that would
result in cainism. Female black kites preferentially fed the smallest chicks and exhibited behaviours to reduce sibling aggression,
contrary to observations in other siblicidal species. In a highly opportunistic forager such as the black kite, a strategy
may exist to protract the life of all the chicks in the brood, waiting for unpredictable situations of food overabundance.
This would induce the appearance of a parent-offspring conflict over brood reduction, reflected in the existence of a possible
anticipated response by some of the chicks (cainism) and in the appearance of special behaviours by the parents to selectively
feed smaller chicks or reduce sibling aggression. In this facultatively siblicidal species, cainism does not seem to be the
final stage of an evolutionary trend favouring the raising of high-quality chicks, but a manifestation of a parent-offspring
conflict over brood size.
Received: 9 March 1998 / Accepted after revision: 8 August 1998 相似文献
38.
In our introduction to this special issue, we explain why understanding the social and situational context around workplace mistreatment is important. We then provide summaries of the six articles in this special issue and conclude by identifying three key themes—social interpretation, recursive nature of mistreatment, and beyond the dyad—and some important directions for future research. 相似文献
39.
Avian sibling aggression plays an important role in controlling food distribution among nest mates. The food-amount hypothesis
predicts that the amount of food obtained by siblings acts as a proximate cue controlling their level of aggression. The importance
of this cue to cattle egrets (Bubulcus ibis) in Oklahoma was evaluated by studying parental feeding rates, food distribution among nestlings, and nestling aggression
in three-chick broods [A-(oldest), B-, and C-chicks]. We compared nests in which siblicide occurred to nests where all three
chicks survived (nonsiblicide nests). Relative to nonsiblicide nests, siblicide nests received decreasing amounts of food
as the day of siblicide approached. Similarly, aggression levels of all three chicks in siblicide nests increased significantly
compared with nonsiblicide nests, with most of the aggressive behavior involving B- and C-chicks. As a result, on a per-day
basis, food amount and aggression exhibited a strong, negative correlation, thus providing support for the food-amount hypothesis.
Though the total amount of food delivered to siblicide nests declined on the days prior to siblicide, the amount of food received
by A-chicks in these nests did not. Relative to nonsiblicide nests, A-chicks in siblicide nests received an increased share
(percent of volume) of the food delivered at the expense of C-chicks, with the percent remaining the same for B-chicks. The
percentage of food B-chicks received the day after siblicide increased significantly from that received the day before siblicide,
with no change occurring in either the amount or percentage of food received by A-chicks; clearly, B-chicks were the beneficiary
of their aggressive actions that resulted in the death of C-chicks. We provide evidence supporting the hypothesis that aggression
is proximately linked to food amount, possibly by a relatively simple cue such as hunger.
Received: 25 November 1994/Accepted after revision: 10 February 1996 相似文献
40.
Jürgen Heinze Diethe Ortius Manfred Kaib Bert Hölldobler 《Behavioral ecology and sociobiology》1994,35(2):75-83
Colonies of the slave-making ant, Harpagoxenus sublaevis, may simultaneously contain workers of several Leptothorax slave species. We observed aggressive interactions among slave-makers, between slavemakers and slaves, and among slaves in 11 mixed colonies. The first two types of aggression appear to be correlated with reproductive competition for the production of males. Aggressive interactions among slaves, however, occurred mainly between slaves belonging to different species. In two colonies, in which one slave species clearly outnumbered the other, the majority attacked and finally expelled all nestmates belonging to the minority species. Our observations thus suggest that in Harpagoxenus colonies a homogeneous colony odor is not always achieved and that heterospecific slaves may occasionally be mistaken for alien ants. Gas chromatographic analyses of ants from mixed colonies similarly show that cuticular hydrocarbon profiles may differ strongly between heterospecific nestmate slaves. 相似文献