Search results for "Amphipod"

Do invasive macroalgae influence biodiversity and abundance of Amphipod Crustaceans ?

2013

Amphipods are an essential element of the food web in marine coastal environments, and represent a good indicator of the health of the ecosystems. The composition of amphipod assemblage is often linked to algal coverage, in which the benthic species find refuge from predators and a great availability of food resources. Within the management and conservation of natural environments, one of the main problems is currently represented by the invasion of non-indigenous species, which modifies native communities. This research compares the amphipod fauna associated with Asparagopsis taxiformis (Delile) Trevisan de Saint-Léon, a non-indigenous red macroalga widely distributed along the west coast …

Mitochondrial DNA variation and the evolutionary history of cryptic Gammarus fossarum types.

2000

The evolutionary history of the cryptic Gammarus fossarum species complex (Crustacea, Amphipoda) in Central Europe was approached by investigating the genetic variation in populations of a natural contact zone. Nucleotide sequence variation of a 395-bp segment of the mitochondrial 16S rRNA gene was compared to that of six nuclear allozyme loci. Three major mtDNA lineages were found, the eastern clade being consistent with the former allozyme type A. The two western clades (types B and C) were not distinguished previously. Strong sequence divergence and correlation with nuclear genetic isolation in syntopic populations, however, justifies the specific status of the three G. fossarum types. T…

Biological invasion and parasitism: invaders do not suffer from physiological alterations of the acanthocephalan Pomphorhynchus laevis.

2009

SUMMARYBiological invasions expose parasites to new invasive hosts in addition to their local hosts. However, local parasites are often less successful in infecting and exploiting their new hosts. This may have major consequences for the competitive ability of hosts, and finally on the fate of the parasite-host community. In Burgundy (Eastern France), the acanthocephalan parasite,Pomphorhynchus laevis, infects 2 amphipod species living in sympatry: the nativeGammarus pulexand the invasiveGammarus roeseli. WhileP. laevisaffects the behaviour and the immunity ofG. pulex,G. roeseliseems unaffected by the infection. In this study, we examined in detail the ability of the parasite to affect the …

Overestimation of the strength of size-assortative pairing in taxa with cryptic diversity: a case of Simpson's paradox.

2015

5 pages; International audience; Size-assortative pairing is one of the most common pairing patterns observed in nature and it probably occurs in many taxa with cryptic diversity. Observed patterns of size-assortative pairing in natural populations may thus be influenced by the co-occurrence of noninterbreeding cryptic groups of individuals living in sympatry. To quantify this potential bias, we sampled amphipods from the Gammarus pulex/Gammarus fossarum crustacean species complex in rivers containing two sympatric and morphologically cryptic groups, i.e. molecular operational taxonomic units (MOTUs). Within each river, MOTUs did not interbreed and differed in mean body size. We measured th…

A network of Italian amphipodologists in the frame of MOTax (Marine Organisms Taxonomy) at the Stazione Zoologica Anton Dohrn di Napoli (Italy)

2017

Talitraits: a taxonomic backbone for talitrid amphipods’ traits

2019

Variations of vitamin D-like reactivity in the crustacean Orchestia cavimana during the molt cycle

1991

An investigation into vitamin D-like molecules has been performed on whole extracts of the terrestrial amphipod Orchestia cavimana, using a sensitive nonequilibrium assay employing 1,25-(OH)2 D receptor from calf thymus. Relatively large amounts of these secosteroid-like molecules were observed and they varied in concentration according to the stages of the molt cycle. The amplitude of these variations reaches a ratio of about 40 from the minimum in premolt to the intermolt sharp peak.

Increased susceptibility to predation and altered anti-predator behaviour in an acanthocephalan-infected amphipod.

2007

7 pages; International audience; According to the 'parasitic manipulation hypothesis', phenotypic changes induced by parasites in their intermediate hosts are effective means of increasing trophic transmission to final hosts. One obvious prediction, although seldom tested, is that increased vulnerability of infected prey to an appropriate predator should be achieved by the parasite altering the anti-predator behaviour of its intermediate host. In this study, we tested this prediction using the fish acanthocephalan Pomphorhynchus tereticollis and the freshwater amphipod Gammarus pulex. Firstly, we estimated the relative vulnerability of infected and uninfected gammarids to predation by the b…

Infection with acanthocephalans increases the vulnerability of Gammarus pulex (Crustacea, Amphipoda) to non-host invertebrate predators.

2008

SUMMARYPhenotypic alterations induced by parasites in their intermediate hosts often result in enhanced trophic transmission to appropriate final hosts. However, such alterations may also increase the vulnerability of intermediate hosts to predation by non-host species. We studied the influence of both infection with 3 different acanthocephalan parasites (Pomphorhynchus laevis, P. tereticollis, and Polymorphus minutus) and the availability of refuges on the susceptibility of the amphipod Gammarus pulex to predation by 2 non-host predators in microcosms. Only infection with P. laevis increased the vulnerability of amphipods to predation by crayfish, Orconectes limosus. In contrast, in the ab…

Host manipulation of a freshwater crustacean (Gammarus roeseli) by an acanthocephalan parasite (Polymorphus minutus) in a biological invasion context.

2006

8 pages; International audience; Several gammarid species serve as intermediate hosts for the acanthocephalan parasite Polymorphus minutus. This parasite influences gammarid behaviour in order to favour transmission to its ultimate host, generally a bird. We investigated this host manipulation in Gammarus roeseli, a gammarid species introduced in France 150 years ago which now coexists with several exotic species from different origins. In the field, vertical distribution of G. roeseli revealed a higher proportion of infected individuals close to the water's surface and the size distribution of infected gammarids revealed predation pressure on infected individuals. However, under laboratory…