Search results for "ECR"
showing 10 items of 3689 documents
Micropredation on sea urchins as a potential stabilizing process for rocky reefs
2012
Rocky reefs can shift from forest, a state dominated by erect algae with high biodiversity, to barren, an impoverished state dominated by encrusting algae. Sea urchins, abundant in barrens, are usually held responsible for the maintenance of this state. Predation by large fish can revert the barren state to forest by controlling sea urchin populations. However, the persistence of a community state sometimes seems to be independent from the presence of such large predators, suggesting the existence of other, unknown mechanisms ensuring their stability. Theoretical studies suggest that the settler stage of sea urchins is determinant for maintaining a given rocky reef state. In this study, we …
Assessing the importance of nursery areas of European hake (Merluccius merluccius) using a body condition index
2017
Abstract In this study, we analysed the variability of reserve storage in juvenile European hake (Merluccius merluccius) off the western coasts of Italy (Central Mediterranean Sea). Reserve storage was measured by the hepatosomatic index (HSI), in relation to environmental and population covariates. HSI has been proved to be a consistent measure of energy storage in gadoids, thus reflecting quantity and quality of food availability for growth. Generalized Additive Models for Location, Scale and Shape (GAMLSS) were used to model the effect of depth, bottom temperature, bottom currents, fish density and fish body size on HSI of juvenile European hake. The results revealed that reserve storage…
Mating Status of an Herbivorous Stink Bug Female Affects the Emission of Oviposition-Induced Plant Volatiles Exploited by an Egg Parasitoid
2019
Insect parasitoids are under selection pressure to optimize their host location strategy in order to maximize fitness. In parasitoid species that develop on host eggs, one of these strategies consists in the exploitation of oviposition-induced plant volatiles (OIPVs), specific blends of volatile organic compounds released by plants in response to egg deposition by herbivorous insects. Plants can recognize insect oviposition via elicitors that trigger OIPVs, but very few elicitors have been characterized so far. In particular, the source and the nature of the elicitor responsible of egg parasitoid recruitment in the case of plants induced with oviposition by stink bugs are still unknown. In …
Burial behaviour by dealates of the termite Pseudacanthotermes spiniger (Termitidae, Macrotermitinae) induced by chemical signals from termite corpses
2011
In order to maintain healthy colonies, termite workers dispose of the cadavers of dead nest mates by cannibalism, burial, or necrophoresis. However, when multiple reproductives found a new colony by pleometrosis, there are no worker castes at the early stages of the foundation to eliminate or isolate the corpses. In this study, we showed that in young pleometrotic colonies, reproductives of Pseudacanthotermes spiniger had the ability to perform this task. Because of the claustral conditions, and the potential inability of the dealates to feed on their own, their behaviour was restricted to the burial of the cadaver within the initial chamber. This burial behaviour, previously not reported i…
Local Recruitment in the Greater Flamingo: A New Approach Using Capture- Mark-Recapture Data
1997
International audience; Although the establishment of new individuals in the breeding component of a population is an essential feature of population regulation, only a few attempts have been made to test biological hypotheses about recruitment. Most previous studies rely on ad hoc calculations or are flawed with unwarranted assumptions about survival. We use a recently developed approach, based on capture-mark-recapture, in which analysis of local recruitment is similar to a time-reversed analysis of survival. The basic data set consists of capture histories viewed in reverse order, with initial capture at year of birth, and subsequent observations corresponding to years when the animal ha…
Who is fishing on what stock: population-of-origin of individual cod (Gadus morhua) in commercial and recreational fisheries
2018
AbstractAtlantic cod (Gadus morhua) in Skagerrak are structured into distinct ecotypes or stock components that have been severely depleted over the past decades. To improve our understanding of how local commercial and recreational fisheries influence cod stocks, we investigated whether these user groups target different stock components of cod. Cod were sampled from the recreational rod and line fishery and from commercial shrimp trawlers catching cod as by-catch. Based on a large set of single nucleotide polymorphisms (SNPs), we defined a subset of 27 semi-diagnostic SNPs designed to discriminate between two cod stock components: “inner fjord” cod and “North Sea” cod, designated by their…
In vivoanalysis of the lumenal binding protein (BiP) reveals multiple functions of its ATPase domain
2007
International audience; The endoplasmic reticulum (ER) chaperone binding protein (BiP) binds exposed hydrophobic regions of misfolded proteins. Cycles of ATP hydrolysis and nucleotide exchange on the ATPase domain were shown to regulate the function of the ligand-binding domain in vitro. Here we show that ATPase mutants of BiP with defective ATP-hydrolysis (T46G) or ATP-binding (G235D) caused permanent association with a model ligand, but also interfered with the production of secretory, but not cytosolic, proteins in vivo. Furthermore, the negative effect of BiP(T46G) on secretory protein synthesis was rescued by increased levels of wild-type BiP, whereas the G235D mutation was dominant. U…
Are there so many congeneric species of chironomid larvae in a small stream?
2018
The co-occurrence of larvae of congeneric chironomid species is common in natural stream assemblages, and raises the problem of finding mechanisms to explain the co-existence of species with similar ecological requirements. In this contribution, we explored the co-occurrence of chironomid larvae belonging to congeneric species within four genera of chironomids: Cricotopus, Eukiefferiella, Orthocladius and Rheocricotopus (with 2, 7, 2 and 4 species, respectively) in the headwaters of a small Mediterranean calcareous stream. Due to the intrinsic, natural spatial and temporal variability in these habitats, we studied three different sites at two different seasons within the annual hydrological…
Costs and Benefits of Experimentally Induced Changes in the Allocation of Growth versus Immune Function under Differential Exposure to Ectoparasites
2010
Background Ecological immunology has focused on the costs of investment in immunocompetence. However, understanding optimal resource allocation to immune defence requires also identification of its benefits, which are likely to occur only when parasites are abundant. Methodology We manipulated the abundance of parasitic hen fleas in blue tit (Cyanistes caeruleus) nests, and supplemented their hosts, the nestlings, with methionine (a sulphur amino acid enhancing cell-mediated immunity) during day 3–6. We found a significant interaction between these two experimental factors on the development of immune defences and growth rates. Only in parasitized nests did methionine supplementation boost …
Could male tergal secretions be considered as a nuptial gift in the Madeira cockroach?
2008
International audience; Many male insects provide somatic nuptial gifts that may strongly influence reproductive fitness, ensuring effective copulation or mediating paternal resource benefits in offspring. Although the courtship feeding behaviour on tergal gland secretions has been described in numerous cockroaches, studies on the function of these so-called nuptial gifts are lacking in this group. In this study, we examined, in the Madeira cockroach, Leucophaea maderae, the functional significance of tergal secretions by manipulating their availability on the back of males. We tested whether male tergal secretions function as a form of mating effort, and/or as a form of paternal investment…