Environmental variability can destabilize communities by causing correlated interspecific fluctuations that weaken the portfolio effect, yet evidence of such a mechanism is rare in natural systems. Here, we ask whether the population dynamics of similar sympatric species of a seabird breeding community are synchronized, and if these species have similar exceptional responses to environmental variation. We used a 24‐year time series of the breeding success and population growth rate of a marine top predator species group to assess the degree of synchrony between species demography. We then developed a novel method to examine the species group – all species combined – response to environmental variability, in particular, whether multiple species experience similar, pronounced fluctuations in their demography. Multiple species were positively correlated in breeding success and growth rate. Evidence of “exceptional” years was found, where the species group experienced pronounced fluctuations in their demography. The synchronous response of the species group was negatively correlated with winter sea surface temperature of the preceding year for both growth rate and breeding success. We present evidence for synchronous, exceptional responses of a species group that are driven by environmental variation. Such species covariation destabilizes communities by reducing the portfolio effect, and such exceptional responses may increase the risk of a state change in this community. Our understanding of the future responses to environmental change requires an increased focus on the short‐term fluctuations in demography that are driven by extreme environmental variability. 相似文献
Immunity to malaria is believed to wane with time in the absence of exposure to Plasmodium falciparum infection, but immunoepidemiological data on longevity of immunity remain controversial. We quantified serum cytokines and chemokines by suspension array technology as potential biomarkers for durability of immunity in immigrants with clinical malaria after years without parasite exposure. These were compared to serum/plasma profiles in naïve adults (travelers) and semi-immune adults under continuous exposure, with malaria, along with immigrant and traveler patients without malaria. Immigrants had higher levels of IL-2, IL-5 and IL-8 compared to semi-immune adults with malaria (P≤0.0200). Time since immigration correlated with increased IL-2 (rho=0.2738P=0.0495) and IFN-γ (rho=0.3044P=0.0282). However, immigrants did not show as high IFN-γ concentrations as travelers during a first malaria episode (P<0.0001). Immigrants and travelers with malaria had higher levels of IFN-γ, IL-6, and IL-10 (P<0.0100) than patients with other diseases, and IL-8 and IL-1β were elevated in immigrants with malaria (P<0.0500). Therefore, malaria patients had a characteristic strong pro-inflammatory/Th1 signature. Upon loss of exposure, control of pro-inflammatory responses and tolerance to P. falciparum appeared to be reduced. Understanding the mechanisms to maintain non-pathogenic effector responses is important to develop new malaria control strategies. 相似文献
This study was focused on species of Peziza belonging to the “P. ammophila” complex, using both morphological and molecular approaches. Molecular and morphological analyses showed that several taxa are hidden under the name “ammophila” and, as a consequence, two additional species and one form are established: P. hellenica sp. nov., P. oceanica sp. nov. and P. ammophila f. megaspora f. nov. On the basis of the data that we have, these taxa seem to be related to some geographical areas; P. ammophila appears to be prevalent in northern, central and southern Europe, its f. megaspora is distributed in France and in the Netherlands, P. hellenica comes from Greece and P. oceanica from New Zealand. A cryptic species, not yet circumscribed satisfactorily, is described as P. deceptiva ad int. Moreover, the problem concerning the identification of P. ammophila is raised, the species is epitypified with a sequenced collection from Sicily (Italy) and a key to the species of the complex is provided. 相似文献
Early social conditions are vital for the establishment of future social interactions. Less, however, is known about how differences in early social conditions contribute to the process of individual recognition and subsequently in the decision of associating and exploring behaviours. In this study, we address this gap in the Trinidadian guppy Poecilia reticulata and test the prediction that fish would show a higher tendency to recognize and associate with individuals of similar phenotype. This prediction was tested by comparing the likelihood of association and latency to explore a novel area in males and females when in the presence of individuals that were familiar (reared together but from different populations), from the same population of origin (from the same population but deprived of interaction with each other), or were unfamiliar (different population and have never interacted). Both early social conditions and population of origin (phenotype matching) affected the tendency to shoal and explore. Females, but not males, exhibited identical preference to associate either with unfamiliar females as with familiar females from a different population. Importantly, female preference did not occur with unfamiliar individuals from a different population. In contrast with our prediction, tendency to shoal did not predict exploration propensity. Males always start exploration before the group whenever unfamiliar males composed the group. Females on the other hand only moved to the novel area after seeing the group doing so, revealing sexual dimorphism in exploratory behaviour. Our results provide evidence for a familiarity and phenotypic matching recognition mechanism at the population level and also highlight the importance of accounting for differences between sexes when investigating the effects of early social conditions. 相似文献
The present study evaluated biofilm growth in AISI 316L stainless steel tubes for seawater-cooled exchanger-condensers that had four different arithmetic mean surface roughness values ranging from 0.14 μm to 1.2 μm. The results of fluid frictional resistance and heat transfer resistance regarding biofilm formation in the roughest surface showed increases of 28.2% and 19.1% respectively, compared with the smoothest surface. The biofilm thickness taken at the end of the experiment showed variations of up to 74% between the smoothest and roughest surfaces. The thermal efficiency of the heat transfer process in the tube with the roughest surface was 17.4% greater than that in the tube with the smoothest surface. The results suggest that the finish of the inner surfaces of the tubes in heat exchanger-condensers is critical for improving energy efficiency and avoiding biofilm adhesion. This may be utilised to reduce biofilm adhesion and growth in the design of heat exchanger-condensers. 相似文献
Argentina is a world leader in regards to regulation and adoption of genetically modified (GM) crops. As a consequence, the regulatory aspects of gene editing applied to agriculture were considered proactively by the Argentinian regulators, who implemented simple but solid pioneering regulatory criteria for gene edited crops. At present, the Argentine regulatory system is fully able to establish if a gene-edited crop should be classified (and handled) either as a GM crop or a conventional new variety. To this end, the concept of “novel combination of genetic material” derived from the Cartagena Protocol on Biosafety is of decisive importance. After some pilot cases that have been managed under this criteria, now applicants appreciate the ease, speed and predictability of the regulation. Moreover, it has been considered by other countries in the course of developing their own regulations, thus acting also as a harmonization factor for the safe and effective insertion of these technologies in the global market.