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Different Host Species (different + host_species)
Selected AbstractsAre there general rules governing parasite diversity?DIVERSITY AND DISTRIBUTIONS, Issue 3 2007Small mammalian hosts, gamasid mite assemblages ABSTRACT Parasite biodiversity varies on several scales, and in particular among different host species. Previous attempts at finding relationships between host features and the diversity of the parasite assemblages they harbour have yielded inconsistent results, suggesting strongly that any patterns might be taxon-specific. Here, we examined the potential of three host characteristics (host body mass, basal metabolic rate, and area of the geographical range) as determinants of parasite diversity in one group of ectoparasites, gamasid mites (superfamily Dermanyssoidea), using data from 63 species of small mammalian hosts. Our analyses used three measures of parasite diversity (species richness, the Shannon diversity index, and average taxonomic distinctness), and controlled for sampling effort and phylogenetic influences. Although several significant relationships were observed, they depended entirely on which diversity measure was used, or on which host taxon was investigated (insectivores vs. rodents and lagomorphs). In addition, the present results on patterns of mite diversity were not consistent with those of an earlier study involving roughly the same host taxa and the same biogeographical area, but a different group of ectoparasites, i.e. fleas. Thus, there appears to be no universal determinant of parasite diversity, and associations between host features and parasite diversity probably evolve independently in different host,parasite systems. [source] Local host ant specificity of Phengaris (Maculinea) teleius butterfly, an obligatory social parasite of Myrmica antsECOLOGICAL ENTOMOLOGY, Issue 5 2010MAGDALENA WITEK 1. Phengaris butterflies are obligatory social parasites of Myrmica ants. Early research suggested that there is a different Myrmica host species for each of the five European Phengaris social parasites, but more recent studies have shown that this was an oversimplification. 2. The pattern of host ant specificity within a Phengaris teleius metapopulation from southern Poland is reported. A combination of studying the frequency distribution of Phengaris occurrence and morphometrics on adult butterflies were used to test whether use of different host species is reflected in larval development. 3. Phengaris teleius larvae were found to survive in colonies of four Myrmica species: M. scabrinodis, M. rubra, M. ruginodis, and M. rugulosa. Myrmica scabrinodis was the most abundant species under the host plant but the percentage of infested nests was similar to other host ant species at two sites and lower in comparison to nests of M. rubra and M. ruginodis at the other two sites. Morphometric measurements of adult butterflies reared by wild colonies of M. scabrinodis and M. ruginodis showed that wing size and number of wing spots were slightly greater for adults eclosing from nests of M. ruginodis. 4. Our results suggest that P. teleius in the populations studied is less specialised than previously suggested. The results are consistent with the hypothesis that P. teleius is expected to be the least specific of the European Phengaris species, as it has the largest and best defended fourth-instar caterpillars and, as a predatory species, it spends less time in the central larval chambers of the host colonies. The fact that individuals reared by M. ruginodis had wider hind wings may suggest that P. teleius had better access to resources in M. ruginodis than in M. scabrinodis colonies. [source] Horizontal transmission of Wolbachia in a Drosophila communityECOLOGICAL ENTOMOLOGY, Issue 4 2005Eleanor R. Haine Abstract., 1.,Wolbachia bacteria are reproductive parasites of arthropods and infect an estimated 20% of all insect species worldwide. In order to understand patterns of Wolbachia infection, it is necessary to determine how infections are gained or lost. Wolbachia transmission is mainly vertical, but horizontal transmission between different host species can result in new infections, although its ecological context is poorly understood. Horizontal transmission is often inferred from molecular phylogenies, but could be confounded by recombination between different Wolbachia strains. 2.,This study addressed these issues by using three genes: wsp, ftsZ, and groE, to study Wolbachia infections in fruit- and fungus-feeding Drosophila communities in Berkshire, U.K. 3.,Identical sequences were found for all three genes in Drosophila ambigua and Drosophila tristis. This suggests horizontal transmission of Wolbachia between these two previously unstudied Drosophila species, which may be the result of the two host species sharing the same food substrates or parasites. 4.,Wolbachia infections might be lost from species due to curing by naturally occurring antibiotics and the presence of these is likely to vary between larval food substrates. 5.,It was investigated whether Wolbachia incidence was lower in fungus-feeding than in fruit-feeding Drosophila species, but no significant difference based on food substrate was found. [source] Sequence-related amplified polymorphism, an effective molecular approach for studying genetic variation in Fasciola spp. of human and animal health significanceELECTROPHORESIS, Issue 2 2009Qiao-Yan Li Abstract In the present study, a recently described molecular approach, namely sequence-related amplified polymorphism (SRAP), which preferentially amplifies ORFs, was evaluated for the studies of genetic variation among Fasciola hepatica, Fasciola gigantica and the "intermediate" Fasciola from different host species and geographical locations in mainland China. Five SRAP primer combinations were used to amplify 120 Fasciola samples after ten SRAP primer combinations were evaluated. The number of fragments amplified from Fasciola samples using each primer combination ranged from 12 to 20, with an average of 15 polymorphic bands per primer pair. Fifty-nine main polymorphic bands were observed, ranging in size from 100 to 2000,bp, and SRAP bands specific to F. hepatica or F. gigantica were observed. SRAP fragments common to F. hepatica and the "intermediate" Fasciola, or common to F. gigantica and the "intermediate" Fasciola were identified, excised and confirmed by PCR amplification of genomic DNA using primers designed based on sequences of these SRAP fragments. Based on SRAP profiles, unweighted pair-group method with arithmetic averages clustering algorithm categorized all of the examined representative Fasciola samples into three groups, representing the F. hepatica, the "intermediate" Fasciola, or the F. gigantica. These results demonstrated the usefulness of the SRAP technique for revealing genetic variability between F. hepatica, F. gigantica and the "intermediate" Fasciola, and also provided genomic evidence for the existence of the "intermediate" Fasciola between F. hepatica and F. gigantica. This technique provides an alternative and a useful tool for the genetic characterization and studies of genetic variability in parasites. [source] How two different host species influence the performance of a gregarious parasitoid: host size is not equal to host qualityJOURNAL OF ANIMAL ECOLOGY, Issue 2 2007JOHANNA HÄCKERMANN Summary 1Hyssopus pallidus Askew (Hymenoptera, Eulophidae) is a gregarious ectoparasitoid of the two tortricid moths species Cydia molesta Busck and C. pomonella L. (Lepidoptera, Tortricidae). It paralyses and parasitizes different larval instars of both species inside the apple fruit, which leads to the death of the caterpillar. 2We assessed the influence of host species characteristics and host food on the performance of the parasitoid female in terms of clutch size decisions and fitness of the F1 generation. 3A comparison of clutch size revealed that female parasitoids deposited similar numbers of eggs on the comparatively smaller C. molesta hosts as on the larger C. pomonella hosts. The number of parasitoid offspring produced per weight unit of host larva was significantly higher in C. molesta than in C. pomonella, which is contrary to the general prediction that smaller hosts yield less parasitoid offspring. However, the sex ratio was not influenced by host species that differed considerably in size. 4Despite the fact that less host resources were available per parasitoid larva feeding on C. molesta caterpillars, the mean weight of emerging female wasps was higher in the parasitoids reared on C. molesta. Furthermore, longevity of these female wasps was neither influenced by host species nor by the food their host had consumed. In addition we did not find a positive relationship between adult female weight and longevity. 5Parasitoid females proved to be able to assess accurately the nutritional quality of an encountered host and adjust clutch size accordingly. These findings indicate that host size is not equal to host quality. Thus host size is not the only parameter to explain the nutritional quality of a given host and to predict fitness gain in the subsequent generation. [source] The evolution of host-specific variation in cuckoo eggshell strengthJOURNAL OF EVOLUTIONARY BIOLOGY, Issue 8 2010C. N. SPOTTISWOODE Abstract Cuckoo eggs are renowned for their mimicry of different host species, leading to the evolution of host-specific races (or ,gentes') defined by egg colour and pattern. This study aims to test the prediction that another property of parasitic eggs, namely shell strength, might also have experienced divergent selection within cuckoo species. Host races of the common cuckoo Cuculus canorus encountering stronger host rejection have thicker-shelled eggs than those parasitising less discriminating species, as expected if egg strengthening discourages host rejection. Moreover, in the diederik cuckoo Chrysococcyx caprius, eggshell thickness was correlated across cuckoo gentes and host species, as expected if eggshell strength has been involved in coevolutionary interactions. This is the first report of host-specific differences in cuckoo egg properties other than colour and pattern and lends correlational support to the hypothesis that the strong eggshells of brood parasites are an adaptation to reduce host rejection. [source] Aquabirnaviruses isolated from marine organisms form a distinct genogroup from other aquabirnavirusesJOURNAL OF FISH DISEASES, Issue 11 2004C X Zhang Abstract A phylogenetic tree of aquabirnaviruses, including marine birnaviruses (MABV) and infectious pancreatic necrosis virus (IPNV), was developed based on the nucleotide sequences and deduced amino acid sequences of the polyprotein and VP5 genes of genomic segment A. In the polyprotein of MABV strains, the amino acid sequences were very similar, with identities of 98.3,99.7%. Twenty-one unique amino acid residues were found in the deduced amino acid sequences of the polyprotein gene of MABV strains. The phylogenetic tree based on the nucleotide sequence of genomic segment A and polyprotein sequences showed that 31 aquabirnavirus strains were clustered into seven genogroups. All MABV strains isolated in Japan and Korea were clustered into one genogroup which was distinct from other aquabirnaviruses. The seventh genogroup containing all MABV strains showed amino acid sequence similarities of 80.7,90.6% with other genogroups. In VP5, four unique residues were found in MABV strains when compared with IPNV strains. The MABV strains exhibited amino acid sequence similarities of 63.9,86.4% with IPNV strains. The amino acid sequences of VP5 were conserved among MABV strains, but differed from those of IPNV strains. The MABV strains isolated from different host species and different geographical areas were very similar to each other, suggesting that the MABV are distinct from the other genogroups. [source] Role of host identity in effects of phytogenic mounds on plant assemblages and species richness on coastal arid dunesJOURNAL OF VEGETATION SCIENCE, Issue 5 2007Magdy I. El-Bana Abstract Question: Phytogenic mounds (nebkhas) - the natural accumulation of wind-blown sediments within or around the canopies of plants - have been proposed as important structures for locally maintaining high species richness in coastal and arid ecosystems. Nebkhas are assumed to increase habitat heterogeneity, but what is the importance of the nebkha host species relative to other nebkha characteristics in determining the associated plant assemblages? Are some host species more effective in creating diversity hotspots, or does a single species-area relationship apply to all nebkhas, regardless of host species? Can the influence of the host be ascribed to its indirect effects on abiotic attributes of the nebkha complex? Methods and location: We investigated plant species richness and composition on nebkhas around six psammophytic species on Mediterranean coastal dunes of the Sinai Peninsula. Results: Plant species richness was significantly related to nebkha size by the single power function according to the general prediction of island biogeography theory, but this relationship was modified - though to a limited degree - by nebkha host species identity. Canonical Correspondence Analysis revealed that nebkha host species identity and nebkha environmental and non-environmental factors significantly explained species composition on the nebkhas, but host species identity did so to a greater extent. The latter might reflect differences in seed trapping ability or free space for colonization between host species. Conclusion: Differences in community composition and richness among nebkhas formed by different host species represent a key factor in the maintenance of plant diversity on arid coastal dunes. [source] Calotte morphology in the phylum Dicyemida: niche separation and convergenceJOURNAL OF ZOOLOGY, Issue 4 2003Hidetaka Furuya Abstract The renal sacs of a diversity of cephalopod molluscs were examined to study the morphology of dicyemid mesozoans. Most of the dicyemid species studied were found to be host specific. Typically, two or more species of dicyemids were present in each host species or each host individual. When dicyemid species co-occurred, their calotte shapes were distinctly different. The following variations in calotte shapes were usually detected within a given host individual: (1) when two species of dicyemids were present, two distinct calotte shapes, conical and discoidal, were observed; (2) when three species of dicyemids were present, three types of calotte configurations were observed, conical (two grades) and discoidal; (3) when more than four species of dicyemids were present, at least one species was characterized by its rare irregularly shaped calotte. As a rule, when more than two dicyemid species were present in a single host individual, calotte shapes were dissimilar. Calotte shapes in dicyemid species from different host species more closely resemble each other than those of dicyemids observed within the same host species. Dicyemids with conical or dome-shaped calottes are found within the convolutions or folds of the renal appendages, whereas those with flat, discoidal calottes attach to the surface of the renal appendages. In the dicyemids, calotte morphology seems to result from adaptation to the structure of host renal tissues and helps to facilitate niche separation of coexisting species. [source] Cryptic speciation and patterns of phenotypic variation of a highly variable acanthocephalan parasiteMOLECULAR ECOLOGY, Issue 19 2007M. L. STEINAUER Abstract An investigation of a parasite species that is broadly host- and habitat-specific and exhibits alternative transmission strategies was undertaken to examine intraspecific variability and if it can be attributed to cryptic speciation or environmentally induced plasticity. Specimens of an acanthocephalan parasite, Leptorhynchoides thecatus, collected throughout North America were analysed phylogenetically using sequences of the cytochrome oxidase I gene and the internal transcribed spacer region. Variation in host use, habitat use, and transmission were examined in a phylogenetic context to determine if they were more likely phylogenetically based or due to environmental influences. Results indicated that most of the variation detected can be explained by the presence of cryptic species. The majority of these species have narrow host and microhabitat specificities although one species, which also may comprise a complex of species, exhibits broad host and habitat specificity. Alternate transmission pathways only occurred in two of the cryptic species and correlate with host use patterns. Taxa that mature in piscivorous piscine hosts use a paratenic fish host to bridge the trophic gap between their amphipod intermediate host and piscivorous definitive host. One potential example of environmentally induced variation was identified in three populations of these parasites, which differ on their abilities to infect different host species. [source] Ectomycorrhizal fungal succession in mixed temperate forestsNEW PHYTOLOGIST, Issue 2 2007Brendan D. Twieg Summary ,,Ectomycorrhizal (ECM) fungal communities of Douglas-fir (Pseudotsuga menziesii) and paper birch (Betula papyrifera) were studied along a chronosequence of forest development after stand-replacing disturbance. Previous studies of ECM succession did not use molecular techniques for fungal identification or lacked replication, and none examined different host species. ,,Four age classes of mixed forests were sampled: 5-, 26-, 65-, and 100-yr-old, including wildfire-origin stands from all four classes and stands of clearcut origin from the youngest two classes. Morphotyping and DNA sequences were used to identify fungi on ECM root tips. ,,ECM fungal diversities were lower in 5-yr-old than in older stands on Douglas-fir, but were similar among age classes on paper birch. Host-specific fungi dominated in 5-yr-old stands, but host generalists were dominant in the oldest two age classes. ECM fungal community compositions were similar in 65- and 100-yr-old stands but differed among all other pairs of age classes. ,,Within the age range studied, site-level ECM fungal diversity reached a plateau by the 26-yr-old age class, while community composition stabilized by the 65-yr-old class. Simple categories such as ,early stage', ,multi stage', and ,late stage' were insufficient to describe fungal species' successional patterns. Rather, ECM fungal succession may be best described in the context of stand development. [source] The mode of interaction between Vitis and Plasmopara viticola Berk.PLANT BIOLOGY, Issue 6 2009& Curt. Abstract In order to obtain insight into host responses to grapevine downy mildew (Plasmopara viticola), we compared pathogen development on a panel of Vitis species from North America, Asia and Europe. Leaf discs from different host species were inoculated in parallel, and the colonisation of the mesophyll was visualised by aniline blue staining and quantified with respect to infection incidence and mycelial growth. In parallel, the morphology of guard cells was screened for the presence of an internal cuticular rim after staining with acridine orange and using low-temperature scanning electron microscopy. We observed three response patterns: (i) inhibition of pathogen development early after attachment of zoospores; (ii) successful colonisation of the mesophyll by the pathogen; and (iii) aberrant development, where the pathogen does not attach to guard cells, but produces hyphae on the leaf surface without formation of viable sporangiophores. Inhibition is observed in the North American and Siberian species, successful colonisation prevails in the European hosts, and surface hyphae are found on non-Siberian Asiatic species. We propose that the interaction between host and pathogen is under control of specific signals that have been subject to evolutionary diversification. [source] Genetic characterization by fluorescent AFLP of Pseudomonas savastanoi pv. savastanoi strains isolated from different host speciesPLANT PATHOLOGY, Issue 3 2007A. Sisto The genetic diversity of 71 Pseudomonas savastanoi pv. savastanoi strains isolated from different host species and from diverse geographical regions was determined by fluorescent amplified fragment length polymorphism (f-AFLP) analysis. The study was carried out using three different selective primer combinations. Strains of P. syringae pv. syringae, P. syringae pv. phaseolicola, P. syringae pv. glycinea, P. syringae pv. tagetis and P. amygdali were also included as outgroups. Based on cluster analysis of f-AFLP data, all P. savastanoi pv. savastanoi strains showed a high degree of similarity, grouping in a cluster and forming a taxon clearly separate from outgroup strains. AFLP analyses failed to support placing strains of P. savastanoi pv. savastanoi, P. syringae pv. phaseolicola and P. syringae pv. glycinea in the same species. Strains of P. savastanoi pv. savastanoi formed subclusters that correlated with the host species. Strains identified within these subclusters were related to the geographical region where the strains were isolated. Strains of P. savastanoi pv. savastanoi from olive were divided into two subclusters. Strains from oleander were differentiated from those from ash and were divided into two additional subclusters, distinct from olive strains. Three strains isolated from jasmine showed a high level of similarity among them but, at a lower Dice similarity coefficient, were linked to a subcluster including olive strains. Finally, two strains isolated from privet were similar to strains from olive and were included in the same subcluster. [source] Analyses of RAPD data for detection of host specialization in Sclerotinia homoeocarpaPLANT PATHOLOGY, Issue 2 2000T. Hsiang Upgma analysis, principal component analysis, genetic diversity analysis and genetic distance analysis of RAPD data were used to assess the extent of host specialization in 50 isolates of S. homoeocarpa from five turfgrass hosts. In upgma analysis and principal component analysis, the occurrence of host specialization was not readily apparent based on visual inspection. Genetic diversity analysis showed significant differentiation among isolates from different host species (GST = 0.34, P < 0.001). The strongest evidence for some degree of host specialization came from the statistical analysis of genetic distances among isolates. By grouping pairwise genetic distances between isolates based on their host species, and analysing for average distance within the same host species and among different host species, it was found that the average distance within species was less than among species (P < 0.0001). An analysis of molecular variance of the genetic distances among isolates found that 32.3% of the total variation was attributable to host species. It is concluded that these isolates of S. homoeocarpa showed a weak level of host specialization, which was not readily apparent by upgma or principal component analyses, but was revealed by genetic diversity analysis and statistical analysis of genetic distances among isolates. Inoculation tests on different host species and tests using a greater number of isolates are required to confirm the extent of specialization. [source] Divergent host plant adaptation drives the evolution of sexual isolation in the grasshopper Hesperotettix viridis (Orthoptera: Acrididae) in the absence of reinforcementBIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY, Issue 4 2010TONY GRACE Early stages of lineage divergence in insect herbivores are often related to shifts in host plant use and divergence in mating capabilities, which may lead to sexual isolation of populations of herbivorous insects. We examined host preferences, degree of differentiation in mate choice, and divergence in cuticular morphology using near-infrared spectroscopy in the grasshopper Hesperotettix viridis aiming to understand lineage divergence. In Kansas (USA), H. viridis is an oligophagous species feeding on Gutierrezia and Solidago host species. To identify incipient mechanisms of lineage divergence and isolation, we compared host choice, mate choice, and phenotypic divergence among natural grasshopper populations in zones of contact with populations encountering only one of the host species. A significant host-based preference from the two host groups was detected in host-paired feeding preference studies. No-choice mate selection experiments revealed a preference for individuals collected from the same host species independent of geographic location, and little mating was observed between individuals collected from different host species. Female mate choice tests between males from the two host species resulted in 100% fidelity with respect to host use. Significant differentiation in colour and cuticular composition of individuals from different host plants was observed, which correlated positively with host choice and mate choice. No evidence for reinforcement in the zone of contact was detected, suggesting that divergent selection for host plant use promotes sexual isolation in this species. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 100, 866,878. [source] The Beta-Binomial Model for Host Specificity among Organisms in Trophic InteractionsBIOMETRICS, Issue 3 2000Ola H. Diserud Summary. In this paper, we present a new stochastic model where the host specificity among organisms in trophic interactions in a community, say parasite-host interactions, is estimated by a beta-binomial model. The expected proportion of the host species in a community that a given parasite species is utilizing is modeled as a realization from an inhomogeneous Poisson process, where the rate of this process is assumed to be proportional to a beta probability distribution. The observed number of host species utilized by the parasites is then binomially distributed with the number of trials equaling the number of different host species in the sample. When the degree of polyphagy is estimated by the parameters of the beta-binomial model, quantities like community host specificity and the expected total number of parasite species that will utilize the host species in the community can be predicted as functions of the number of host species available. The predictions can then be applied in analysis of, e.g., symbiotic interactions among organisms, local species richness, and community structure. [source] | |||||||||||||||||||||||||