A multibiomarker approach was developed to evaluate the juvenile European flounder responses to a complex mixture of 9 polycyclic aromatic hydrocarbons (PAHs) and 12 polychlorinated biphenyls (PCBs). Exposure was performed through contaminated food pellets displaying: (1) PAH and PCB levels similar to those detected in the heavily polluted Seine estuary, respectively in sediments and in flatfish and (2) ten times these concentrations. Several biomarkers of the immune system (e.g., lysozyme concentration and gene expression of complement component C3 and TNF-receptor), DNA damage (e.g., Comet assay), energetic metabolism (e.g.,?activity of cytochrome C oxidase), detoxification process (e.g., cytochrome P450 1A1 expression level: CYP1A1; betaine homocysteine methyl transferase expression level: BHMT) were investigated after 14 and 29 days of contamination, followed by a 14-days recovery period. After 29 days of contamination, the detoxification activity (CYP1A1 expression level) was positively correlated with DNA damages; the increase of the BHMT expression level could also be related to the detoxification process. Furthermore, after the recovery period, some biomarkers were still upregulated (i.e., CYP1A1 and BHMT expression levels). The immune system was significantly modulated by the chemical stress at the two concentration levels, and the lysozyme appeared to be the most sensitive marker of the mixture impact. 相似文献
To understand the consequences of the invasion of the nonnative rainbow trout Oncorhynchus mykiss on the native marble trout Salmo marmoratus, we compared two distinct headwater sectors where marble trout occur in allopatry (MTa) or sympatry (MTs) with rainbow trout
(RTs) in the Idrijca River (Slovenia). Using data from field surveys from 2002 to 2009, with biannual (June and September)
sampling and tagging from June 2004 onwards, we analyzed body growth and survival probabilities of marble trout in each stream
sector. Density of age-0 in September over the study period was greater for MTs than MTa and very similar between MTs and
RTs, while density of trout ≥age-1 was similar for MTa and MTs and greater than density of RTs. Monthly apparent survival
probabilities were slightly higher in MTa than in MTs, while RTs showed a lower survival than MTs. Mean weight of marble and
rainbow trout aged 0+ in September was negatively related to cohort density for both marble and rainbow trout, but the relationship
was not significantly different between MTs and MTa. No clear depression of body growth of sympatric marble trout between
sampling intervals was observed. Despite a later emergence, mean weight of RTs cohorts at age 0+ in September was significantly
higher than weight of both MTs and MTa. The establishment of a self-sustaining population of rainbow trout does not have a
significant impact on body growth and survival probabilities of sympatric marble trout. The numerical dominance of rainbow
trout in streams at lower altitudes seem to suggest that while the low summer flow pattern of Slovenian streams is favorable
for rainbow trout invasion, the adaptation of marble trout to headwater environments may limit the invasion success of rainbow
trout in headwaters. 相似文献
Because Tachia guianensis (Gentianaceae) is a “non-specialized myrmecophyte” associated with 37 ant species, we aimed to determine if its presence alters the ant guild associated with sympatric “specialized myrmecophytes” (i.e., plants sheltering a few ant species in hollow structures). The study was conducted in a hilly zone of a neotropical rainforest where two specialized myrmecophytes grow at the bottom of the slopes, another at mid-slope, and a fourth on the hilltops. Tachia guianensis, which occurred everywhere, had its own guild of associated ant species. A network analysis showed that its connections with the four other myrmecophytes were rare and weak, the whole resulting in a highly modular pattern of interactions with one module (i.e., subnetwork) per myrmecophyte. Three ant species parasitized three out of the four specialized myrmecophytes (low nestedness noted), but were not or barely associated with T. guianensis that therefore did not influence the parasitism of specialized myrmecophytes. 相似文献
Precipitation chemistry measurementsobtained by the Canadian Air and PrecipitationMonitoring Network (CAPMoN) and the U.S. NationalAtmospheric Deposition Program/National Trends Network(NADP/NTN) have been examined using more than 7 yrof collocated data from two sites, namely, Sutton,Quebec, Canada and State College, Pennsylvania, U.S.A.In the case of the CAPMoN data, weeklyprecipitation-weighted mean concentrations, totalsample depths and total standard gauge depths werecomputed from daily data and compared to thecorresponding weekly sampling data of the NADP/NTNnetwork. Seasonal and annual precipitation-weightedmean concentrations and deposition values were alsocomputed for both networks and compared. Statisticallysignificant between-network biases were found to existin the weekly results for most of the measuredvariables, particularly standard gauge depth, sampledepth, pH, H+, NO3-,NH4+,Na+; the NADP/NTN values were consistently lowerthan those of CAPMoN with the exception of pH andNa+. The magnitude of the biases was less than35% of the median CAPMoN weekly value for the 7 yr. For most of the measured parameters, thevariability of the between-network differencesrepresented less than 20% of the median CAPMoN weeklyvalue. Both the between-network biases andvariabilities were functions of several physicalparameters, the most dominant being the sample depthand the ionic concentration. For seasonal and annualdeposition values, statistically significantbetween-network biases were found for H+,SO42-, NO3-,Ca2+,NH4+ for both periods; for Mg2+ andK+ for seasonal data; and Cl- for yearlydata, with the NADP/NTN deposition values being lowerthan those of CAPMoN. The relative biases ranged from7 to 37%. Part of the between-network bias in thedeposition estimates was directly attributable to astrong bias in the standard gauge depths of the two networks. 相似文献
In this paper, we propose a simple oligopoly game model to represent the interactions between coalitions of countries in deploying carbon dioxide removal (CDR) strategies in a steady-state net-zero emission climate regime that could take place by the end of the twenty-first century. The emission quotas and CDR activities obtained in the solution of this steady-state model could then be used as a target for end-of-period conditions in a dynamic integrated assessment analysis studying the transition to 2100. More precisely, we analyze a steady-state situation where m coalitions exist and behave as m players in a game of supplying emission rights on an international emission trading system. The quotas supplied by a coalition must correspond to the amount of CO2 captured through CDR activities in the corresponding world region. We use an extension of the computable general equilibrium model GEMINI-E3 to calibrate the payoff functions and compute an equilibrium solution in the noncooperative game.
Intraspecific competition is a pervasive phenomenon with important ecological and evolutionary consequences, yet its effect in natural populations remains controversial. Although numerous studies suggest that in many cases populations across all organisms are limited by density-dependent processes, this conclusion often relies on correlative data. Here, using an experimental approach, we examined the effect of intraspecific competition on population regulation of the ant Aphaenogaster senilis. In this species females are philopatric while males disperse by flying over relatively long distances. All colonies were removed from 15 experimental plots, except for one focal colony in each plot, while 15 other plots remained unmanipulated. After the first reproductive season, nest density in the experimental plots returned to a level nonsignificantly different from that in the control plots, which was not expected if the populations were indeed regulated by density-independent phenomena. In both the control plots and the experimental plots colonies remained overdispersed throughout the experiment, suggesting colony mutual exclusion. Nests outside the plots rapidly extended their foraging span, but we did not detect any significant inward migration into the experimental plots. Experimental reduction in density did not significantly affect the focal colonies' biomass, measured just before the first reproductive season. However, the ratio of males to workers-pupae biomasses was smaller in experimental plots, suggesting that colonies there had redirected part of the resources normally allocated to male production to the production instead of new workers. Microsatellite analysis indicated that, after the reproductive season, many colonies in the experimental plots were headed by a young queen that was the mother of the brood but not of the old workers, indicating that reduction in colony density stimulated fission of the remaining colonies. Finally, at the end of the experiment, 14 months after experimental reduction in density, colonies that derived from fission were smaller in the experimental than in the control plots, suggesting that the former had undergone fission at a smaller size than in control plots, which presumably allowed them to colonize the emptied areas. We conclude that colonies adjust resource allocation and colony fission to the degree of intraspecific competition. 相似文献
The recognition of food-provisioning parents is crucial for fledglings of many bird species. Vocalizations are the most commonly
used cues in avian parent–offspring communication, and it has been shown in several species that fledglings respond specifically
to their parents' contact calls. However, fledglings occasionally also react to unrelated adults. Such responses may reflect
recognition errors or alternatively a strategy of fledglings to obtain food or other direct benefits from unrelated adult
birds. In a playback experiment, we tested whether zebra finch Taeniopygia guttata fledglings perceive variation in adult call signatures to recognize their parents and whether the propensity to respond to
unrelated individuals is related to the gender of adults and to signal properties of male and female calls. Male calls are
learnt and show high intra-sexual variation, which may improve the accurate recognition of the father's individual signature.
In contrast, calls of adult females are innate, show lower intra-sexual variation such that the mother's call is more likely
to be confused with another female call. We demonstrate that fledglings are able to recognize their parents. In addition,
fledglings reacted more strongly to unrelated females compared with unrelated males. Our findings suggest that responses to
unrelated adults may reflect recognition errors and indicate the importance of variation in identity signals for individual
recognition processes in parent–offspring communication. 相似文献
Preservation of small natural areas is not in itself a sufficient measure to maintain the integrity of the ecosystems for
which they were initially set aside. Intense pressure from recreational use is just one of the many human-caused stresses
that may degrade natural areas. Therefore, land-use planning and management from an ecological perspective is necessary to
assess, ensure, and in some cases increase, the ecological integrity of protected natural areas. An ecosystem management approach
for small protected natural areas with high recreational use is presented, based on three interrelated components: an ecological
evaluation procedure of ecosystems, the implementation of management interventions on ecosystems, and the development of a
monitoring scheme of ecosystem components. The ecological evaluation procedure combines two concepts: the biotic value of
vegetation and wildlife and the abiotic fragility of the soils. This combined evaluation process results in the creation of
a sensitivity map that can be used as a management tool for planners and managers. Management interventions, the second component
of the management approach, are derived from concepts of ecological succession. Intentional human interventions are used to
maintain the ecological integrity of ecosystems or in some cases to restore degraded sites. For the third component, only
the basic principles of the monitoring program will be discussed. A pilot project in one of the Montreal urban community protected
areas is presented to illustrate aspects of the proposed ecosystem management approach. 相似文献
In many ants, young queens disperse by flying away from their natal nest and found new colonies alone (independent colony
founding, ICF). Alternatively, in some species, ICF was replaced by colony fission, in which young queens accompanied by workers
found a new colony at walking distance from the mother nest. We compared the queen morphology of Cataglyphis floricola, which disperses by fission, with that of its most likely living ancestor, Cataglyphis emmae, which disperses by ICF. As in other species, the transition from ICF to fission is associated with queen miniaturization.
Interestingly, C. floricola presents two types of small queens: brachypters (with short non-functional wings) and ergatoids (worker-like apterous queens).
Ergatoids are, on average, 2.8 mg lighter and have half the number of ovarioles than brachypters, which limits the advantage
for a colony to produce ergatoids instead of brachypters. Furthermore, more ergatoids are produced than brachypters, but their
individual survival rate is lower. During colony fission, 96% of the cocoons containing brachypters but only 31% of those
containing ergatoids are transferred to the daughter nests where, after emergence, they compete for becoming the next queen.
The remaining queen cocoons, which stay in the mother queen's nest, are eliminated by workers upon emergence, probably to
maintain monogyny. This waste of energy suggests that producing ergatoids instead of brachypters is unlikely to increase colony
efficiency. We argue that the evolution of ergatoids could derive from a selfish larval strategy, developing into worker-like
queens in spite of the colony interest. 相似文献
Regional Environmental Change - Climate change and a growing population around the Mediterranean Rim are increasing the need for water and, consequently, the pressure on resources in terms of both... 相似文献