Search results for "amphipod"
showing 10 items of 126 documents
Anxiété et manipulation parasitaire chez un invertébré aquatique : approches évolutive et mécanistique
2020
Trophically transmitted parasites induce changes in their host’s phenotype. These changes are supposed to increase transmission probability to definitive hosts through the predation of intermediate hosts. This phenomenon is known as ‘parasite manipulation’ has been hypothesized to be an adaptive trait of parasites for a long time. As manipulation involves predator-prey interactions, it is therefore necessary to understand how antipredatory behaviours are modulated by exogenous (predation pressure) and endogenous (infection, emotional state) factors. We tried to go into this phenomenon in depth, in amphipods, by responding toseveral questions : (1) what is the extent of the multidimensionali…
Status of Corynosoma (Acanthocephala: Polymorphidae) based on anatomical, ecological, and phylogenetic evidence, with the erection of Pseudocorynosom…
2006
The possession of genital spines has been considered as a key taxonomic trait to differentiate Corynosoma from other genera of the Polymorphidae. However, Corynosoma currently consists of 2 groups of species with clear ecological and morphological divergences: the "marine" group (with ca. 30 species) infects mammals and piscivorous birds in the marine realm, whereas the "freshwater" group (with ca. 7 species) infects waterfowl in continental waters. Species from these groups differ in shape of body and neck, trunk spination, lemnisci length and shape, testes arrangement, and number and shape of cement glands. We tested whether species from these 2 groups formed a monophyletic assemblage bas…
The ‘killer shrimp’Dikerogammarus villosus(Crustacea, Amphipoda) invading Alpine lakes: overland transport by recreational boats and scuba-diving gea…
2013
The alien freshwater amphipod of Ponto-Caspian origin, Dikerogammarus villosus, also known as the killer shrimp, is recognized as being one of the worst invasive alien species in Europe, representing a major conservation problem. Recently, the species has been reported to invade lakes in the Alps in putative association with overland transport linked with recreational activities. This study provided a method to assess risk associated with this overland transport and an opportunity to set up a rationale for effective preventive conservation management. A field survey of 60 lakes encompassing all the Alpine area has revealed the presence of killer shrimp in 12 lakes. Subsequent multivariate d…
Males do not always switch females when presented with a better reproductive option
2014
8 pages; International audience; Paired individuals are expected to leave their current partner for newly encountered ones of higher quality. In such cases, animals should therefore be able to compare the quality of their current partner to the quality of a new prospective mate next to the couple. We tested this prediction in Gammarus pulex, an amphipod species where paired males have been described to switch females before copulation. Contrary to expectations, a majority of males remained paired to their current female when presented to an unpaired female of higher quality. In fact, males did not seem to compare the quality of the 2 females before switching. They rather based their decisio…
Evolutionary histories of symbioses between microsporidia and their amphipod hosts : contribution of studying two hosts over their geographic ranges.
2019
Title: Evolutionary histories of symbioses between microsporidia and their amphipod hosts : contribution of studying two hosts over their geographic ranges.Keywords: Symbioses, Phylogeny, Phylogeography, Amphipods, Host-Parasite, MicrosporidiaAbstract: Microsporidia are obligate endoparasites, exploiting their hosts with either vertical or horizontal transmission. While the former may promote co-speciation and host-specificity, the latter may promote shifts between host species. Freshwater amphipods are hosts for many microsporidian species, but no general pattern of host specificity and co-diversification is known.In my PhD work microsporidian infections, identified with SSU rDNA, were ass…
No room for males in caves: Female-biased sex ratio in subterranean amphipods of the genus Niphargus.
2021
Sex allocation theory predicts that the proportion of daughters to sons will evolve in response to ecological conditions that determine the costs and benefits of producing each sex. All else being equal, the adult sex ratio (ASR) should also vary with ecological conditions. Many studies of subterranean species reported female-biased ASR, but no systematic study has yet been conducted. We test the hypothesis that the ASR becomes more female-biased with increased isolation from the surface. We compiled a data set of ASRs of 35 species in the subterranean amphipod Niphargus, each living in one of three distinct habitats (surface-subterranean boundary, cave streams, phreatic lakes) representing…
The legacy of a vanished sea: a high level of diversification within a European freshwater amphipod species complex driven by 15 My of Paratethys reg…
2016
16 pages; International audience; The formation of continental Europe in the Neogene was due to the regression of the Tethys Ocean and of the Paratethys Sea. The dynamic geology of the area and repetitious transitions between marine and freshwater conditions presented opportunities for the colonization of newly emerging hydrological networks and diversification of aquatic biota. Implementing mitochondrial and nuclear markers in conjunction with a large-scale sampling strategy, we investigated the impact of this spatiotemporal framework on the evolutionary history of a freshwater crustacean morphospecies. The Gammarus balcanicus species complex is widely distributed in the area previously oc…
Magnitude and direction of parasite‐induced phenotypic alterations: a meta‐analysis in acanthocephalans
2020
Several parasite species have the ability to modify their host's phenotype to their own advantage thereby increasing the probability of transmission from one host to another. This phenomenon of host manipulation is interpreted as the expression of a parasite extended phenotype. Manipulative parasites generally affect multiple phenotypic traits in their hosts, although both the extent and adaptive significance of such multidimensionality in host manipulation is still poorly documented. To review the multidimensionality and magnitude of host manipulation, and to understand the causes of variation in trait value alteration, we performed a phylogenetically corrected meta-analysis, focusing on a…
Investigating the emerging role of comparative proteomics in the search for new biomarkers of metal contamination under varying abiotic conditions
2016
13 pages; International audience; This study aims at investigating the potential use of comparative proteomics as a multi-marker approach of metal contamination, taking into account the potential confounding effect of water temperature. The major objective was to identify combinations of proteins specifically responding to a given metal, even if included in a metal mixture. The diagnostic approach was performed via the comparative analysis of protein expression on spot mapping provided by adult males of Gammarus pulex (Amphipoda, Crustacea) respectively exposed to arsenate (As), cadmium (Cd) or a binary mixture of these metals (AsCd) at three realistic temperatures (5, 10 and 15 °C). Proteo…
Diel Feeding Features of Juveniles of Two Sparids in the Stagnone di Marsala Coastal Sound (Western Sicily, Italy)
2001
Diet composition, feeding rhythms, gastric evacuation rates, daily rations of Diplodus puntazzo (Gmelin 1789) and Sarpa salpa (Linneo 1758) juveniles were studied in order to investigate their trophic ecology, niche breadth and overlap. These Sparids were collected in the Stagnone di Marsala (Western Sicily), in April 1997, in a 24 hour sampling period. Gastric content of 86 specimens of D. puntazzo (standard length = 31.9 ± 6.6 mm; body wet weight = 1.0 Ī 0.5 g) and of 100 specimens of S. salpa (standard length = 32.3 ± 2.9 mm; body wet weight = 0.6 Ī 0.2 g) were examined. Amphipoda and Tanaidacea were the most frequent prey items in stomach content of D. puntozzo, while Hydrozoa, Bryozoa …