scholarly journals Host specificity and the probability of discovering species of helminth parasites

Parasitology ◽  
2005 ◽  
Vol 130 (6) ◽  
pp. 709-715 ◽  
Author(s):  
R. POULIN ◽  
D. MOUILLOT

Different animal species have different probabilities of being discovered and described by scientists, and these probabilities are determined to a large extent by the biological characteristics of these species. For instance, species with broader geographical ranges are more likely to be encountered by collectors than species with restricted distributions; indeed, the size of the geographical range is often the best predictor of a species' date of description. For parasitic organisms, host specificity may be similarly linked to the probability of a species being found. Here, using data on 170 helminth species parasitic in freshwater fishes, we show that host specificity is associated with the year in which the helminths were described. Helminths that exploit more host species, and to a lesser degree those that exploit a broader taxonomic range of host species, tend to be discovered earlier than the more host-specific helminths. This pattern was observed across all helminth species, as well as within the different helminth taxa (trematodes, cestodes, nematodes and acanthocephalans). Our results demonstrate that the parasite species known at any given point in time are not a random subset of existing species, but rather a biased subset with respect to the parasites' biological properties.

Parasitology ◽  
2003 ◽  
Vol 126 (5) ◽  
pp. 473-480 ◽  
Author(s):  
R. POULIN ◽  
D. MOUILLOT

The host specificity of a parasite is not merely a function of how many host species it can exploit, but also of how closely related these host species are to each other. Here, a new index of host specificity is proposed, one that takes into account the average taxonomic or phylogenetic distance between pairs of host species used by a parasite. The index is derived from measures of taxonomic distinctness used in biodiversity studies. It is easy to compute and interpret, ranging from a minimum value of 1 when all host species are members of the same genus, to a maximum of 5, when all host species belong to different classes. The variance of this measure can also be computed, and provides additional information on the taxonomic or phylogenetic structure of the host assemblage. Using data on helminth parasites of Canadian freshwater fishes, we show that the new index, unlike the mere number of known host species, is independent of study effort i.e. the number of published records of a parasite. Although the index and the number of known hosts are not entirely independent statistically, each captures a different aspect of host specificity. For instance, although acanthocephalans infect significantly more host species than trematodes, cestodes or nematodes, there is no difference in the average index value among these 4 helminth taxa, suggesting that the average taxonomic distances between the host species of a parasite do not vary among these higher taxa. We recommend the use of our new index in future comparative studies of host specificity, in particular when the focus is on the evolutionary history of parasites and of their past colonizations of host lineages.


Zootaxa ◽  
2008 ◽  
Vol 1721 (1) ◽  
pp. 1 ◽  
Author(s):  
FABIANO M. VIEIRA ◽  
JOSÉ L. LUQUE ◽  
LUIS C. MUNIZ-PEREIRA

Ninety-five helminth parasite species totaling 480 records (including 60 new host and geographical records) in 21 species of wild carnivore mammals from Brazil were listed. Nineteen undetermined helminth species and 4 undetermined host species were also included. Information about the site of infection of parasites, localities, references and a host-parasite list were included herein.


2019 ◽  
Vol 94 ◽  
Author(s):  
A. Spickett ◽  
K. Junker ◽  
G. Froeschke ◽  
V. Haukisalmi ◽  
S. Matthee

Abstract Currently, descriptive information on the host range and geographic distribution of helminth parasites associated with naturally occurring rodents in South and southern Africa is scant. Therefore, we embarked on a countrywide study to: (1) identify gastrointestinal helminths and their host range, and (2) provide baseline data on the geographic distribution of helminths across the country. Altogether, 55 helminth taxa were recovered from at least 13 rodent species (n = 1030) at 26 localities across South Africa. The helminth taxa represented 25 genera (15 nematodes, nine cestodes and one acanthocephalan). Monoxenous nematodes were the most abundant and prevalent group, while the occurrence of heteroxenous nematodes and cestodes was generally lower. The study recorded several novel helminth–host associations. Single-host-species infections were common, although multiple-host-species infections by helminth species were also recorded. Monoxenous nematodes and some cestodes were recovered countrywide, whereas heteroxenous nematodes were restricted to the eastern regions of South Africa. The study highlights the as yet unexplored diversity of helminth species associated with naturally occurring rodent species and provides initial data on their geographical distribution in South Africa.


Zootaxa ◽  
2009 ◽  
Vol 2123 (1) ◽  
pp. 1-45 ◽  
Author(s):  
LUÍS C. MUNIZ-PEREIRA ◽  
FABIANO M. VIEIRA ◽  
JOSÉ L. LUQUE

Using available records, unpublished information retrieved from the Helminthological Collection of the Oswaldo Cruz Institute (CHIOC) and published reports, a checklist of the recorded helminth parasites of endangered vertebrates from Brazil was generated. A total of 772 records and 186 helminth species (6 Acanthocephala, 83 Nematoda, 23 Cestoda, 64 Trematoda, 10 Monogenea) in 76 host species (7 Actinopterygii, 8 Chondrichthyes, 1 Amphibia, 10 Reptilia, 22 Aves, 28 Mammalia) from Brazil were listed in the present work, including 39 undetermined helminth species and 10 new host records. This is the first compilation of the helminth parasites of threatened vertebrates in Brazil and in the Neotropics.


1998 ◽  
Vol 46 (5) ◽  
pp. 473 ◽  
Author(s):  
I. Beveridge ◽  
N. B. Chilton ◽  
P. M. Johnson ◽  
L. R. Smales ◽  
R. Speare ◽  
...  

The occurrence of gastrointestinal helminth parasites in 40 Macropus agilis, 12 M. antilopinus, 39 M. dorsalis, 28 M. giganteus, 29 M. parryi, 30 M. robustus and 26 Wallabia bicolor from north and central Queensland was examined. A total of 124 morphologically defined species of helminth was encountered, comprising 103 species of strongyloid nematodes, 6 species of trichostrongyloid nematodes, 2 species of spiruroid nematodes, 4 species of oxyuroid nematodes, 7 species of anoplocephalid cestodes and 2 species of digenetic trematodes. Helminth communities in each macropodid host species exhibited a high level of diversity, and were dominated numerically by strongyloid nematodes. A high proportion of the helminth species was restricted to a single host species and there was a low level of similarity between helminth communities in different host species. Similarities that did occur were not apparently related to the phylogenetic relationships between hosts and are best explained by host switching between hosts sharing overlapping habitats and feeding preferences. There was poor separation of the helminth species into ‘core’, ‘secondary’ and ‘satellite’ members of communities.


2016 ◽  
Vol 94 (11) ◽  
pp. 761-765 ◽  
Author(s):  
K.M. Campião ◽  
O.T. Dias ◽  
R.J. Silva ◽  
V.L. Ferreira ◽  
L.E.R. Tavares

Sympatric hosts are exposed to similar ecological conditions, particularly if they are closely related phylogenetically and share some physiological and behavioral traits. We studied the sympatric frogs Leptodactylus chaquensis Cei, 1950 and Leptodactylus podicipinus (Cope, 1862) to investigate the extent to which the helminth parasite communities were influenced by host species’ characteristics or habitat location. We described and compared the helminth communities of 50 L. chaquensis and 40 L. podicipinus collected concurrently from two different study sites in Brazil’s Pantanal floodplain. Similarities in the prevalence and mean abundance of helminths were higher among allopatric populations of the same species than among sympatric populations of different species. The effects of host species, size, and habitat on helminth composition were significant. The amount of variance in the helminth community composition explained by host species and size was greater than that explained by host habitat. These results indicate that the main factors determining similarities in parasite species in this study system are the coevolutionary and biological constraints of the host species, which either limit or allow infection of the parasite species despite the host habitat.


Parasitology ◽  
2004 ◽  
Vol 130 (1) ◽  
pp. 109-115 ◽  
Author(s):  
R. POULIN

Parasites often exploit more than one host species at any stage in their life-cycle, but the extent to which these host species are used varies greatly. Parasites typically achieve their highest prevalence, intensity and/or abundance in one host species (the principal host), whereas infection levels in auxiliary hosts range from relatively high to very low. The present study examines what influences the distribution of parasite individuals among their different host species, using metazoan parasites that use freshwater fish as their definitive or only host. Specifically, I test the hypothesis that differences in relative infection levels by a parasite among its auxiliary hosts are proportional to the taxonomic distance between the respective auxiliary hosts and the parasite's principal host. Taxonomic distance among hosts is a surrogate measure of their similarity in terms of ecology, physiology and immunology. Using data on 29 parasite species and 6 fish communities, for a total of 47 parasite-locality combinations, it was found that taxonomic distance between the auxiliary hosts and the principal host had no real influence on infection levels in auxiliary hosts, measured as either prevalence, intensity or abundance. The analysis revealed differences in the degree of specialization among major groups of parasites: in terms of abundance or intensity, auxiliary hosts were less important for cestodes than for nematodes and copepods. The lack of an effect of taxonomic distance may indicate that ecological similarity among host species, arising from convergence and not from relatedness, is more important than host phylogeny or taxonomy. Although the results are based on a limited number of parasite taxa, they suggest that parasites may be opportunistic in their colonization of new hosts, and not severely constrained by evolutionary baggage.


2015 ◽  
Vol 16 (1) ◽  
pp. 1-56 ◽  
Author(s):  
Ahmet Öktener

AbstractThis new checklist is an update of helminths of freshwater fish from Turkey. The last publication of a checklist of helminth parasites of freshwater fish in Turkey was over 11 years ago (Öktener, 2003), and there have been a number of new records. This update includes additional records and allows for the correction of errors and omissions that were present in the preceding version. The revision literature indicated the occurrence of 123 parasite species which included 60 monogeneans, 20 digeneans, 20 cestodes, 11 nematodes, seven acanthocephalans, five annelids from 71 different wild fish (64 native, four transitional, three introduced fish) species from freshwater in Turkey. Parasites not identified to species level are listed separately, and not included in the resulting comments, because of reporting different host species. Cyprinidae, with 50 species, is the dominant family among the examined fish with regard to species diversity


1970 ◽  
Vol 44 (2) ◽  
pp. 169-188 ◽  
Author(s):  
Chandra Sekhar S. ◽  
William Threlfall

808 cunners,Tautogolabrus adspersus(Walbaum) were obtained from eight sampling stations around the Newfoundland coast, during the periods August-September, 19G7 and July-October, 1908. The fish were examined for metazoan parasites using conventional parasitological techniques. 22 species of parasites (10 trematode; 5 cestode; 6 nematode; 1 acanthocephalan) were recovered. This number excludes metacercariae ofCryptocotyle lingua(Creplin, 1825). 19 are new host records. Details of infections with the various species are given, each species being discussed and/or described individually. No leeches were found on this host despite the fact that it lives in. close proximity to other fish species that are heavily infested and an experiment performed to determine if leeches would move from one host species to another gave negative results.


1981 ◽  
Vol 59 (11) ◽  
pp. 2172-2176 ◽  
Author(s):  
Michael D. Rigby ◽  
William Threlfall

One hundred and fourteen muskrats (Ondatra zibethicus (L.)), collected between September 1977 and January 1979 in three areas of insular Newfoundland, were examined for helminths, with 11 species being found (7 Digenea, 2 Cestoda, and 2 Nematoda). Diplostomum mergi was recovered from a mammal for the first time. Distribution along the alimentary tract was examined and all helminths recovered preferred the proximal 60% of the small intestine, except Quinqueserialis quinqueserialis and Trichostrongylus calcaratus, which preferred the caecum. Adult and immature muskrats showed differences in the prevalence and intensity of infection and the adults also had larger concurrent infections. In only one case, namely Hymenolepis evaginata, was a parasite species more prevalent in one sex (the males). Small seasonal differences in prevalence and (or) intensity of infection were noted for some parasites and were related to differences in parasite burden of adult and immature hosts and water temperature. A difference in the occurrence of Digenea between sample areas was related to water pH and hardness.


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