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101.
Damien Denis Jean-Sébastien PierreJoan van Baaren Jacques J.M. van Alphen 《Ecological modelling》2011,222(9):1604-1613
Adult parasitoid females lay their eggs in or on host insects. Most species are incapable of de novo lipogenesis as adults, and lipids accumulated during the larval stage are allocated either to egg production or to adult survival. Lipid consumption increases with distance covered by the parasitoids and thus with the distance between available hosts within a habitat. Temperature should affect parasitoid fitness because it changes the constraint imposed by a limited reserve of lipids and because it influences behaviour. Climate change involves both an increase in average temperature and an increased frequency of extreme weather such as heat waves. We investigated how the predicted increase of temperature will affect parasitoid fitness and how this depends on habitat parameters (spatial distribution of hosts and lipid cost of habitat exploitation). We studied optimal behaviour and calculated fitness at different temperatures and in different habitats using a stochastic dynamic programming model for pro-ovigenic parasitoids (which mature all their eggs before becoming adult). We show that an increase in temperature decreases fitness of parasitoids adapted to lower temperatures. This decrease in fitness depends on habitat quality. In field conditions (assuming small costs of intra-patch foraging), the loss of fitness should be larger in habitats with high inter-patch distance and in habitats with a more aggregated distribution of hosts. The foraging behaviour of parasitoids is also affected; at higher temperature we show that intra-patch foraging becomes less efficient, and patch residence times are longer. 相似文献
102.
Jacques Marsot Laurent Claudon 《International journal of occupational safety and ergonomics》2013,19(1):13-23
As a marked increase in the number of musculoskeletal disorders was noted in many industrialized countries and more specifically in companies that require the use of hand tools, the French National Research and Safety Institute (INRS) launched in 1999 a research project on the topic of integrating ergonomics into hand tool design, and more particularly to a design of a boning knife.After a brief recall of the difficulties of integrating ergonomics at the design stage, the present paper shows how 3 design methodological tools—Functional Analysis, Quality Function Deployment and TRIZ—have been applied to the design of a boning knife. Implementation of these tools enabled us to demonstrate the extent to which they are capable ofresponding to the difficulties ofintegrating ergonomics into product design. 相似文献
103.
104.
Julien Thébault Laurent Chauvaud Jacques Clavier Renaud Fichez Eric Morize 《Marine Biology》2006,149(2):257-267
The periodicity of striae formation in the tropical scallop Comptopallium radula (Indo-West Pacific Ocean) was investigated with an in situ marking technique, using the calcein fluorochrome. To minimize scallop stress caused by excessive handling, in situ benthic chambers were used for marking experiments. Once marked, scallops (shell height range: 38.4–75.8 mm) remained on site in a large benthic enclosure and were collected at regular time intervals to count new striae formed after marking, over a period of 3 months. A 3-h exposure period with calcein (150 mg l−1) was sufficiently long to create a detectable mark in nearly all shells. It was, however, impossible to count the striae in 48.2% of the shells (mainly large specimens) because of a very small growth after marking. Lack of significant mortality during the experiments indicated that tested calcein concentrations were not lethal. A decrease in shell growth rate was observed after marking but the respective impacts of calcein toxicity and changes in environmental conditions could not be discriminated. Our results suggest that in situ calcein marking inside benthic chambers is suitable for shell growth studies of scallops, provided the latter are not too old. After marking, the juvenile C. radula formed an average of one stria every 2.1 days in summer. Reports of 2-day periodicity in biological rhythms are rare. Striae formation in C. radula may be controlled by an endogenous oscillator, synchronized by an environmental cue acting as a zeitgeber, such as seawater temperature or sea level pressure, both of which exhibit 2-day variations in the Pacific Ocean. As in many other scallop species, C. radula forms striae periodically under natural conditions, but this study shows that in pectinid juveniles, this periodicity can deviate from a daily cycle. These results suggest that C. radula shells have tremendous potential for recording environmental conditions during periods ranging from months to a few years and with a resolution of 2 days. 相似文献
105.
Hora RR Ionescu-Hirsh A Simon T Delabie J Robert J Fresneau D Hefetz A 《Die Naturwissenschaften》2008,95(1):55-60
In the ectatommine ant Ectatomma tuberculatum, the visual appearance of queens changes after mating and ovarian development in that their cuticle turns from shiny to matte.
In this study, we have shown that this change seems to be caused by 15-fold accumulation of hydrocarbons, in particular heptacosane
that covers the multiple grooves present on the cuticular surface creating a wax coat in mated fully fertile queens. Analyses
of the scrapped wax revealed that it is composed largely of heptacosane. Peak-by-peak comparison of the cuticular hydrocarbon
(CHC) composition of mated, virgin with developed ovaries and virgin with nondeveloped ovaries revealed significant differences
between the queen groups. Although the total amount of the CHC of virgin queens with developed ovaries was not higher than
virgin queens that did not have developed ovaries, the composition showed a shift toward the mated queen. While it is possible
that the large accumulation of hydrocarbons may give extra physical and chemical protection to queens, we propose that the
switch in the relative abundance of heptacosane and nonacosane and perhaps of other components is indicative of being a mating
and fertility cue. This is the first report in social insects where external chemical changes are accompanied by changes in
visual appearance. 相似文献
106.
Alain Dejean Céline Leroy Bruno Corbara Régis Céréghino Olivier Roux Bruno Hérault Vivien Rossi Roberto J. Guerrero Jacques H. C. Delabie Jérôme Orivel Raphaël Boulay 《Die Naturwissenschaften》2010,97(10):925-934
Myrmecophytes offer plant-ants a nesting place in exchange for protection from their enemies, particularly defoliators. These obligate ant–plant mutualisms are common model systems for studying factors that allow horizontally transmitted mutualisms to persist since parasites of ant–myrmecophyte mutualisms exploit the rewards provided by host plants whilst providing no protection in return. In pioneer formations in French Guiana, Azteca alfari and Azteca ovaticeps are known to be mutualists of myrmecophytic Cecropia (Cecropia ants). Here, we show that Azteca andreae, whose colonies build carton nests on myrmecophytic Cecropia, is not a parasite of Azteca–Cecropia mutualisms nor is it a temporary social parasite of A. alfari; it is, however, a temporary social parasite of A. ovaticeps. Contrarily to the two mutualistic Azteca species that are only occasional predators feeding mostly on hemipteran honeydew and food bodies provided by the host trees, A. andreae workers, which also attend hemipterans, do not exploit the food bodies. Rather, they employ an effective hunting technique where the leaf margins are fringed with ambushing workers, waiting for insects to alight. As a result, the host trees’ fitness is not affected as A. andreae colonies protect their foliage better than do mutualistic Azteca species resulting in greater fruit production. Yet, contrarily to mutualistic Azteca, when host tree development does not keep pace with colony growth, A. andreae workers forage on surrounding plants; the colonies can even move to a non-Cecropia tree. 相似文献
107.
Madagascar provides some of the rare examples where two or more primate species of the same genus and with seemingly identical
niche requirements occur in sympatry. If congeneric primate species co-occur in other parts of the world, they differ in size
in a way that is consistent with Hutchinson’s rule for coexisting species, or they occupy different ecological niches. In
some areas of Madagascar, mouse lemurs do not follow these “rules” and thus seem to violate one of the principles of community
ecology. In order to understand the mechanisms that allow coexistence of sympatric congeneric species without obvious niche
differentiation, we studied food composition of two identical sized omnivorous mouse lemur species, Microcebus griseorufus and M. murinus with the help of stable isotope analyses (δ
15N and δ
13C). The two species are closely related sister species. During the rich season, when food seems abundant, the two species
do not differ in their nitrogen isotope composition, indicating that the two species occupy the same trophic level. But they
differ in their δ
13C values, indicating that M. griseorufus feeds more on C4 and CAM (Crassulacean-acid-metabolism) plants than M. murinus. During the lean season, M. murinus has lower δ
15N values, indicating that the two species feed at different trophic levels during times of food shortage. Hybrids between
the two species showed intermediate food composition. The results reflect subtle differences in foraging or metabolic adaptations
that are difficult to quantify by traditional observations but that represent possibilities to allow coexistence of species. 相似文献
108.
Jacques Henry 《Disasters》2013,37(2):293-316
This paper proposes an inductive analysis of the decision as to whether to return or to relocate by persons in the State of Louisiana, United States, who evacuated after Hurricanes Katrina and Rita in August and September 2005, respectively. Drawing on interviews with evacuees in these events and extensive fieldwork in the impacted area, the paper seeks to identify the folk dimensions of the decision‐making process, assess their arrangements, and situate the process in the larger context of risk and resilience in an advanced society. It suggests that, despite the material and emotional upheaval experienced by affected persons, the decision‐making process is a rational endeavour combining a definite set of tightly interconnected factors, involving material dimensions and substantive values that can act in concert or in conflict. In addition, it indicates that there are significant variations by geographic areas, homeownership, and kind of decision. Some theoretical implications, practical measures, and suggestions for future research are examined. 相似文献
109.
Lynda Aissani Florent Jabouille Jacques Bourgois Patrick Rousseaux 《Process Safety and Environmental Protection》2012,90(4):295-303
The life cycle of a product is generally characterized by the main following stages: raw materials acquisition, manufacturing, processing and formulation, distribution and transportation, use, re-use, maintenance, recycle and waste management. As regards the process, the following stages are usually distinguished: raw materials acquisition, process manufacture, use and dismantling at the end of the lifetime. Considering the life cycle concept in a risk analysis approach requires the adjustment of the classic risk analysis methodology. In order to build up this new methodology called LCRA (Life Cycle Risk Assessment), we relied on the LCA (Life Cycle Assessment) methodology, which allows the assessment of the potential environmental impacts throughout the life cycle of a system. Once these adjustments made, this new methodology LCRA is explained and applied to two energy pathways (or life cycles): hydrogen (produced from the biomass) and gasoline pathways. 相似文献
110.
Antoine Carlier Bénédicte Ritt Clara F. Rodrigues Jozée Sarrazin Karine Olu Jacques Grall Jacques Clavier 《Marine Biology》2010,157(11):2545-2565
Cold seep communities in the Mediterranean Sea have only been discovered two decades ago, and their trophic ecology has been
the subject of very few studies. We investigated the benthic food web of two deep chemosynthesis-based ecosystems on the Napoli
and Amsterdam mud volcanoes (MVs) in the eastern Mediterranean Sea (~2,000 m depth). Seeping methane has been detected at
the surface of both MVs during pioneering cruises and has been hypothesised to be assimilated by benthic fauna as observed
in other oceans’ margins. Given the extreme oligotrophic character of the eastern Mediterranean Sea, we a priori expected
that chemosynthetic food sources, especially methane-derived carbon (MDC), played a major trophic role in these deep seep
communities relative to what has been observed in other seep systems worldwide. We aimed at unravelling the trophic relationships
on Napoli and Amsterdam MVs through the analysis of carbon, nitrogen and sulphur isotopes both in the dominant benthic invertebrates
including the small endofauna (300 μm < size < 1 cm) and in the sedimented organic matter. In particular, we assessed the
fraction of MDC in the tissue of several heterotrophic and symbiotic species. Low mean δ34S and δ13C values (0.4 ± 4.8‰ and −31.6 ± 5.7‰, respectively) obtained for mega- and macrofauna suggested that the investigated benthic
food webs are virtually exclusively fuelled by carbon of chemosynthetic origin. A few grazer invertebrates (δ34S up to 11‰) depart from this trend and could complement their diet with sedimented and decayed phytoplanktonic organic matter.
Faunal δ13C values indicated that the oxidation of sulphur is likely the predominant energetic pathway for biosynthesis on both MVs.
Nevertheless, mytilid bivalves and small capitellid, ampharetid and spionid polychaetes were 13C-depleted (δ13C < −37‰) in a way indicating they assimilated a significant portion of MDC. For these later heterotrophic species, MDC ranged
between 21 and 31% (lower estimates) and 97 and 100% (upper estimates). However, our results highlighted that the origin of
assimilated carbon may be complex for some symbiotic species. The vestimentiferan tubeworm Lamellibrachia sp., which exclusively depends on its sulphur-oxidising endosymbionts, showed a ~20‰ inter-individual δ13C variability on a very small spatial scale (<1 m) at the summit of Napoli MV. This mostly reflects the variable isotopic
composition of pore-water-dissolved inorganic carbon (DIC) and evidenced that tubeworms (and subsequently their endosymbionts)
uptake DIC derived from multiple methane oxidation processes in varying proportions. The lower and upper MDC estimates for
the vestimentum of Napoli’s individuals were 11–38 and 21–73%, respectively. Finally, data on trophic ecology of Napoli and
Amsterdam MVs clearly corroborate previous geophysical results evidencing the spatial heterogeneity of Mediterranean MV environmental
conditions. 相似文献