Nejvíce citovaný článek - PubMed ID 22967821
Does invasive Chondrostoma nasus shift the parasite community structure of endemic Parachondrostoma toxostoma in sympatric zones?
Monogenean parasites are often co-introduced with their fish hosts into novel areas. This study confirmed co-introduction of two dactylogyrids, Dactylogyrus squameus Gusev, 1955 and Bivaginogyrus obscurus (Gusev, 1955), and a newly described gyrodactylid species, Gyrodactylus pseudorasborae n. sp. into Europe along with their fish host, the invasive topmouth gudgeon Pseudorasbora parva (Temminck & Schlegel) from East Asia. All three species were observed in the lower Dnieper and middle Danube basin regions and had slightly larger haptoral hard parts than the same parasites in their native range. While dactylogyrids occurred sporadically, we recorded regular infection by G. pseudorasborae n. sp. at relatively high prevalence and abundance. This latter species was observed in both the native and non-native range of topmouth gudgeon, and resembles Gyrodactylus parvae You et al., 2008 recently described from P. parva in China. Both species were distinguished based on genetic analysis of their ITS rDNA sequence (6.6% difference), and morphometric differences in the marginal hooks and male copulatory organ. Phylogenetic analysis of dactylogyrid monogeneans showed that B. obscurus clustered with Dactylogyrus species parasitising Gobionidae and Xenocyprididae, including D. squameus, supporting recent suggestions of a paraphyletic origin of the Dactylogyrus genus. In addition to co-introduced parasites, topmouth gudgeon was infected with a local generalist, G. prostae Ergens, 1964, increasing the number of monogeneans acquired in Europe to three species. Nevertheless, monogenean infections were generally lower in non-native host populations, potentially giving an advantage to invading topmouth gudgeon.
TITLE: Les parasites d’un envahisseur à succès : les monogènes du goujon asiatique Pseudorasbora parva, avec description d’une nouvelle espèce de Gyrodactylus. ABSTRACT: Les parasites monogènes sont souvent co-introduits avec leurs hôtes poissons dans de nouvelles zones. Cette étude a confirmé la co-introduction de deux Dactylogyridae, Dactylogyrus squameus Gusev, 1955 et Bivaginogyrus obscurus (Gusev, 1955), et d’une espèce de Gyrodactylidae nouvellement décrite, Gyrodactylus pseudorasborae n. sp. en Europe, en même temps que leur hôte poisson, le goujon envahissant Pseudorasbora parva (Temminck & Schlegel) qui vient d’Asie de l’Est. Les trois espèces ont été observées dans les régions du bas Dniepr et du bassin moyen du Danube et avaient des parties sclérifiées haptorales légèrement plus grandes que les mêmes parasites dans leur aire de répartition d’origine. Alors que les Dactylogyridae étaient rares, nous avons enregistré une infection régulière par G. pseudorasborae n. sp. à une prévalence et une abondance relativement élevées. Cette dernière espèce a été observée à la fois dans l’aire de répartition indigène et non indigène du goujon asiatique et ressemble à Gyrodactylus parvae You et al., 2008 récemment décrit chez P. parva en Chine. Les deux espèces ont été distinguées sur la base de l’analyse génétique de leur séquence ITS de l’ADNr (différence de 6,6 %) et des différences morphométriques dans les crochets marginaux et l’organe copulateur mâle. L’analyse phylogénétique des monogènes Dactylogyridae a montré que B. obscurus se regroupait avec des espèces de Dactylogyrus parasitant les Gobionidae et les Xenocyprididae, y compris D. squameus, soutenant les suggestions récentes d’une origine paraphylétique du genre Dactylogyrus. En plus des parasites co-introduits, le goujon asiatique était infecté par un généraliste local, G. prostae Ergens, 1964, portant le nombre de monogènes acquis en Europe à trois espèces. Néanmoins, les infections par les monogènes étaient généralement plus faibles dans les populations d’hôtes non indigènes, donnant potentiellement un avantage à l’invasion du goujon asiatique.
- Klíčová slova
- Bivaginogyrus, Monogenea, New species, Parasite loss, Phylogeny, Species invasion,
- MeSH
- Cyprinidae * parazitologie MeSH
- fylogeneze MeSH
- máloostní * MeSH
- nemoci ryb * epidemiologie parazitologie MeSH
- paraziti * MeSH
- Trematoda * genetika MeSH
- zvířata MeSH
- Check Tag
- mužské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
The genes of the major histocompatibility complex (MHC) are an essential component of the vertebrate immune system and MHC genotypes may determine individual susceptibility to parasite infection. In the wild, selection that favors MHC variability can create situations in which interspecies hybrids experience a survival advantage. In a wild system of two naturally hybridizing leuciscid fish, we assessed MHC IIB genetic variability and its potential relationships to hosts' ectoparasite communities. High proportions of MHC alleles and parasites were species-specific. Strong positive selection at specific MHC codons was detected in both species and hybrids. MHC allele expression in hybrids was slightly biased towards the maternal species. Controlling for a strong seasonal effect on parasite communities, we found no clear associations between host-specific parasites and MHC alleles or MHC supertypes. Hybrids shared more MHC alleles with the more MHC-diverse parental species, but expressed intermediate numbers of MHC alleles and positively selected sites. Hybrids carried significantly fewer ectoparasites than either parent species, suggesting a hybrid advantage via potential heterosis.
- MeSH
- alely * MeSH
- Bayesova věta MeSH
- biologická evoluce * MeSH
- biologické modely MeSH
- Cyprinidae genetika MeSH
- hlavní histokompatibilní komplex MeSH
- hybridizace genetická * MeSH
- hybridní efekt * genetika MeSH
- křížení genetické MeSH
- lineární modely MeSH
- selekce (genetika) * MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
BACKGROUND: Host specificity is one of the outputs of the coevolution between parasites and their associated hosts. Several scenarios have been proposed to explain the pattern of parasite distribution in parental and hybrid genotypes ranging from hybrid resistance to hybrid susceptibility. We hypothesized that host-parasite co-adaptation limits the infection of host-specific parasites in hybrid genotypes even under the condition of the high frequency of hybrids. The experimental monogenean infection in pure breeds of Blicca bjoerkna and Abramis brama and cross-breeds (the F1 generation of hybrids) under the condition of similar frequencies of pure and hybrid genotypes was investigated. We also examined the potential effect of the maternal origin of hybrids (potential co-adaptation at the level of mitochondrial genes) on monogenean abundance. METHODS: Pure breeds of two cyprinids and two cross-breeds (one with B. bjoerkna, the next with A. brama in the maternal positions) were exposed to infection by monogeneans naturally occurring in B. bjoerkna and A. brama. The experiment was run under similar frequencies of the four breed lines. RESULTS: We showed similar levels of monogenean infection in B. bjoerkna and A. brama. However, each species harboured specific monogenean fauna. Hybrids harboured all monogenean species specifically infecting one or the other species. Monogenean infection levels, especially those of Dactylogyrus specific to A. brama, were lower in hybrids. For the majority of host-specific parasites, there was no effect of the maternal origin of hybrids on monogenean abundance. Asymmetry was found in the distribution of specific parasites in favour of specialists of B. bjoerkna in the monogenean communities of hybrids. CONCLUSIONS: Our results indicate that the maternal mtDNA of hybrids is not an important predictor of host-specific monogenean infection, which may suggest that mitochondrial genes are not strongly involved in the coadaptation between monogeneans and their associated hosts. The asymmetry of species-specific parasites suggests similarity between the molecular components of the immune mechanisms in hybrids and B. bjoerkna. Our results revealed a difference between the degree of host-parasite coadaptation in specific parasites of A. brama and the degree of host-parasite coadaptation in specific parasites of B. bjoerkna and their associated hosts.
- Klíčová slova
- Coadaptation, Cyprinid fish, Host specificity, Hybridization, Monogenean infection,
- MeSH
- Cyprinidae genetika parazitologie MeSH
- fylogeneze MeSH
- fyziologická adaptace MeSH
- genotyp MeSH
- hostitelská specificita * MeSH
- infekce červy třídy Trematoda * MeSH
- interakce hostitele a parazita MeSH
- mitochondriální geny * MeSH
- nemoci ryb parazitologie MeSH
- ryby MeSH
- Trematoda MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
BACKGROUND: Recently, human intervention enabled the introduction of Barbus barbus from the Rhône River basin into the Barbus meridionalis habitats of the Argens River. After an introduction event, parasite loss and lower infection can be expected in non-native hosts in contrast to native species. Still, native species might be endangered by hybridization with the incomer and the introduction of novel parasite species. In our study, we aimed to examine metazoan parasite communities in Barbus spp. populations in France, with a special emphasis on the potential threat posed by the introduction of novel parasite species by invasive B. barbus to local B. meridionalis. METHODS: Metazoan parasite communities were examined in B. barbus, B. meridionalis and their hybrids in three river basins in France. Microsatellites were used for the species identification of individual fish. Parasite abundance, prevalence, and species richness were compared. Effects of different factors on parasite infection levels and species richness were tested using GLM. RESULTS: Metazoan parasites followed the expansion range of B. barbus and confirmed its introduction into the Argens River. Here, the significantly lower parasite number and lower levels of infection found in B. barbus in contrast to B. barbus from the Rhône River supports the enemy release hypothesis. Barbus barbus × B. meridionalis hybridization in the Argens River basin was confirmed using both microsatellites and metazoan parasites, as hybrids were infected by parasites of both parental taxa. Trend towards higher parasite diversity in hybrids when compared to parental taxa, and similarity between parasite communities from the Barbus hybrid zone suggest that hybrids might represent "bridges" for parasite infection between B. barbus and B. meridionalis. Risk of parasite transmission from less parasitized B. barbus to more parasitized B. meridionalis indicated from our study in the Argens River might be enhanced in time as higher infection levels in B. barbus from the Rhône River were revealed. Hybrid susceptibility to metazoan parasites varied among the populations and is probably driven by host-parasite interactions and environmental forces. CONCLUSIONS: Scientific attention should be paid to the threatened status of the endemic B. meridionalis, which is endangered by hybridization with the invasive B. barbus, i.e. by genetic introgression and parasite transmission.
- Klíčová slova
- Biological invasion, Cyprinid fish, Hybridization, Metazoan parasite communities,
- MeSH
- biodiverzita * MeSH
- chiméra klasifikace genetika růst a vývoj parazitologie MeSH
- Cyprinidae klasifikace genetika růst a vývoj parazitologie MeSH
- mikrosatelitní repetice MeSH
- parazitární zátěž MeSH
- paraziti klasifikace izolace a purifikace MeSH
- řeky MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Geografické názvy
- Francie MeSH
Two cyprinid species, Parachondrostoma toxostoma, an endemic threatened species, and Chondrostoma nasus, an invasive species, live in sympatry in southern France and form two sympatric zones where the presence of intergeneric hybrids is reported. To estimate the potential threat to endemic species linked to the introduction of invasive species, we focused on the DAB genes (functional MHC IIB genes) because of their adaptive significance and role in parasite resistance. More specifically, we investigated (1) the variability of MHC IIB genes, (2) the selection pattern shaping MHC polymorphism, and (3) the extent to which trans-species evolution and intergeneric hybridization affect MHC polymorphism. In sympatric areas, the native species has more diversified MHC IIB genes when compared to the invasive species, probably resulting from the different origins and dispersal of both species. A similar level of MHC polymorphism was found at population level in both species, suggesting similar mechanisms generating MHC diversity. In contrast, a higher number of DAB-like alleles per specimen were found in invasive species. Invasive species tended to express the alleles of two DAB lineages, whilst native species tended to express the alleles of only the DAB3 lineage. Hybrids have a pattern of MHC expression intermediate between both species. Whilst positive selection acting on peptide binding sites (PBS) was demonstrated in both species, a slightly higher number of positively selected sites were identified in C. nasus, which could result from parasite-mediated selection. Bayesian clustering analysis revealed a similar pattern of structuring for the genetic variation when using microsatellites or the MHC approach. We confirmed the importance of trans-species evolution for MHC polymorphism. In addition, we demonstrated bidirectional gene flow for MHC IIB genes in sympatric areas. The positive significant correlation between MHC and microsatellites suggests that demographic factors may contribute to MHC variation on a short time scale.
- MeSH
- alely MeSH
- Bayesova věta MeSH
- Cyprinidae klasifikace genetika MeSH
- fylogeneze MeSH
- geny MHC třídy II * MeSH
- molekulární evoluce * MeSH
- ohrožené druhy * MeSH
- polymorfismus genetický MeSH
- rekombinace genetická MeSH
- zavlečené druhy MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
BACKGROUND: Host specificity varies among parasite species. Some parasites are strictly host-specific, others show a specificity for congeneric or non-congeneric phylogenetically related host species, whilst some others are non-specific (generalists). Two cyprinids, Cyprinus carpio and Carassius gibelio, plus their respective hybrids were investigated for metazoan parasites. The aim of this study was to analyze whether interspecies hybridization affects host specificity. The different degrees of host specificity within a phylogenetic framework were taken into consideration (i.e. strict specialist, intermediate specialist, and intermediate generalist). METHODS: Fish were collected during harvesting the pond and identified using meristic traits and molecular markers. Metazoan parasite species were collected. Host specificity of parasites was determined using the following classification: strict specialist, intermediate specialist, intermediate generalist and generalist. Parasite species richness was compared between parental species and their hybrids. The effect of host species on abundance of parasites differing in host specificity was tested. RESULTS: Hybrids harbored more different parasite species but their total parasite abundance was lower in comparison with parental species. Interspecies hybridization affected the host specificity of ecto- and endoparasites. Parasite species exhibiting different degrees of host specificity for C. carpio and C. gibelio were also present in hybrids. The abundance of strict specialists of C. carpio was significantly higher in parental species than in hybrids. Intermediate generalists parasitizing C. carpio and C. gibelio as two phylogenetically closely related host species preferentially infected C. gibelio when compared to C. carpio, based on prevalence and maximum intensity of infection. Hybrids were less infected by intermediate generalists when compared to C. gibelio. CONCLUSIONS: This finding does not support strict co-adaptation between host and parasite genotypes resulting in narrow host specificity, and showed that hybrid genotypes are susceptible to parasites exhibiting host specificity. The immune mechanisms specific to parental species might represent potential mechanisms explaining the low abundance of parasites in C. gibelio x C. carpio hybrids.
