Search results for "Host"
showing 10 items of 1982 documents
The role of local adaptation in the relationship between an endangered root hemiparasite Euphrasia rostkoviana, and its host, Agrostis capillaris
1999
We experimentally studied the role of local adaptation and the co-evolutionary relationship between an annual, endangered root hemiparasite Euphrasia rostkoviana and its main host Agrostis capillaris. According to our hypothesis, the existence of local adaptation in hemiparasites should be observable in better hemiparasite performance when attached to A. capillaris hosts originating from Euphrasia populations. After one month of growth, the height and the number of leaves of hemiparasites were not affected by the origin of their hosts. The differences in growth were due to between population effects. The situation remained constant after three months. Hemiparasite biomass was not affected b…
Continental-scale patterns of pathogen prevalence: a case study on the corncrake
2014
Pathogen infections can represent a substantial threat to wild populations, especially those already limited in size. To determine how much variation in the pathogens observed among fragmented populations is caused by ecological factors, one needs to examine systems where host genetic diversity is consistent among the populations, thus controlling for any potentially confounding genetic effects. Here, we report geographic variation in haemosporidian infection among European populations of corncrake. This species now occurs in fragmented populations, but there is little genetic structure and equally high levels of genetic diversity among these populations. We observed a longitudinal gradient…
Population structure of a parasitic plant and its perennial host
2002
Characterization of host and parasite population genetic structure and estimation of gene flow among populations are essential for the understanding of parasite local adaptation and coevolutionary interactions between hosts and parasites. We examined two aspects of population structure in a parasitic plant, the greater dodder (Cuscuta europaea) and its host plant, the stinging nettle (Urtica dioica), using allozyme data from 12 host and eight parasite populations. First, we examined whether hosts exposed to parasitism in the past contain higher levels of genetic variation. Second, we examined whether host and parasite populations differ in terms of population structure and if their populati…
About the Influences of Some Major Biotic Drivers on the Population Dynamics in Host-parasite Systems: Interpretative Lessons from an Extended Nichol…
2020
Population dynamics within host-parasite systems in insects is governed by a series of factors, both endogenous and exogenous. Among them, five factors may be considered as major drivers: the respective inherent rates of increase of the host and of the parasite, the level of resource available to the host, the respective immigration rates of the host and of the parasite. While only the first two (the inherent rates of increase of host and parasite) are considered in the original Nicholson and Bailey model, an extended version of the model includes also the other three parameters, thus providing a broader (although still schematic) approach to the host-parasite population dynamics. A brief a…
Seasonal population dynamics of Zeuxapta seriolae (Monogenea: Heteraxinidae) parasitising Seriola dumerili (Carangidae) in the Western Mediterranean.
2013
We examined the seasonal and yearly population dynamics of the monogenean pathogen Zeuxapta seriolae on juvenile fish from wild populations of Seriola dumerili. The study is based on bimonthly monitoring between April, 2005 and April, 2007 off Majorca, and newly obtained monogenean population data for juvenile fish from three additional localities in the Western Mediterranean (off Alicante, Corsica and Sardinia). We documented the highest intensities and abundances of Z. seriolae, with mean abundance values similar to or higher than those reported in the single case of wild fish mortalities reported to date. There was a recurrent pattern of seasonal change in infection with Z. seriolae in t…
On the infracommunity structure of adult cestodes in freshwater fishes.
1990
The distribution–co-occurrence and exchange of adult cestode species in two fish communities (the Bothnian Bay and Lake Yli-Kitka both in Finland) was studied. Coexistence of two or more mature cestode species in the same fish host population was zero for all fish species studied (33) except pike in the Bothnian Bay and whitefish in the lake. It was found that 60% of the fish species studied in the Bothnian Bay and 80% of the fish species studied from Lake Yli-Kitka harboured only 1 mature cestode species. Exchange of adult cestode species between the different fish species in these two fish communities was found to be as rare as coexistence. The infra-community structure of adult cestodes …
Population structure and incidence of the stolbur phytoplasma vectorHyalesthes obsoletus(Cixiidae) among geographic regions in Switzerland
2013
The dissemination of stolbur phytoplasma (16Sr-XIIA group)-induced yellows diseases depends on the dispersal biology and host plant fidelity of the planthopper vector Hyalesthes obsoletus (Hemiptera: Cixiidae). We analysed the degree of these two properties in H. obsoletus by studying its population genetic structure and stolbur infection rates relative to the two major host plants, Convolvolus arvensis and Urtica dioica, in order to infer relevant divisions for stolbur epidemiology in Swiss viticultural regions. Three regional populations with the potential to determine stolbur epidemiology in distinct ways were identified. First, populations associated with U. dioica in northern Switzerla…
Host‐parasite relationships between two seal populations and two species of Corynosoma (Acanthocephala) in Finland
1988
Ringed seals (Phoea hispida botnica), from the Bothnian Bay, north-eastern Baltic Sea were examined for acanthocephalan parasites in 1977-1982, and specimens from Lake Saimaa in south-eastern Finland (P. h. saimensis) were examined in 1980-1981. The two seal stocks have been isolated from Arctic stock for 11,000 years and from each other for 8,000 years. Corynosoma strumosum and C. semerme were found in the Baltic seals, but only C. strumosurn in those from the lake. Eighty two of the ringed seals caught in the Bothruan Bay were infected with both Corynosoma species, one with a single infection of C. strumosum and one with C. semerme inautumn. The total number of C. semerme increased in rel…
Ecological study of the wood mouse helminth community in a burned Mediterranean ecosystem in regeneration five years after a wildfire
2007
AbstractParasites are used as biological tags in environmental impact studies. However, terrestrial systems in general and small mammals in particular are rarely considered in these ecological studies. Based on the effects of a wildfire which occurred in the Spanish Serra Calderona Natural Park — a typical Mediterranean ecosystem — the regeneration process of the wood mouse population and its helminth community is analysed. A total of 217 individuals of Apodemus sylvaticus were studied in a five year period, from the second to the fifth post-fire year: 152 mice originating from the burned area and 65 from the control — non-burned — area. The helminth community for both burned and non-burned…
Differences in parasite susceptibility and costs of resistance between naturally exposed and unexposed host populations
2009
It is generally assumed that resistance to parasitism entails costs. Consequently, hosts evolving in the absence of parasites are predicted to invest less in costly resistance mechanisms than hosts consistently exposed to parasites. This prediction has, however, rarely been tested in natural populations. We studied the susceptibility of three naïve, three parasitized and one recently isolated Asellus aquaticus isopod populations to an acanthocephalan parasite. We found that parasitized populations, with the exception of the isopod population sympatric with the parasite strain used, were less susceptible to the parasite than the naïve populations. Exposed but uninfected (resistant) isopods f…