Niche restriction in parasites: proximate and ultimate causes

Parasitology ◽  
1994 ◽  
Vol 109 (S1) ◽  
pp. S69-S84 ◽  
Author(s):  
K. Rohde
Keyword(s):  
Interspecific Competition ◽  
Host Species ◽  
Feeding Habits ◽  
Geographical Range ◽  
Physical Factors ◽  
Reproductive Barriers ◽  
Intermediate Hosts ◽  
Specific Chemical ◽  
Morphological Adaptations ◽  
Marine Parasites

SUMMARYHutchinson's (1957) definition of an ecological niche as a multidimensional hypervolume determined by a number of physical and biotic variables is adopted. The number of niche dimensions is very great, but as a working hypothesis it is assumed that a few are sufficient to characterize the niche of a parasite species to a high degree of accuracy. They are host species, microhabitat(s), macrohabitat(s), geographical range, sex and age of host, season, food and hyperparasites. Methods to measure niche width, in particular specificity indices, are discussed, and some examples of niche restriction are described. Proximate and ultimate causes of niche restriction are discussed, mainly using marine parasites as examples. Among proximate causes of one niche dimension, host specificity, are ecological factors restricting exposure to infection to certain host species; host-specific chemical factors that induce hatching, direct infective stages to a host and bring about settlement of a parasite; factors that lead to mortality in or on the wrong host; morphological adaptations that guarantee survival in or on the ‘correct’ host; and availability of suitable hosts. Many factors are likely to be responsible for microhabitat specificity, but have been little studied, except for some physiological and morphological adaptations to particular microhabitats. Macrohabitats and geographical range may be determined by the distribution of intermediate hosts and certain food items, and by a variety of chemical and physical factors. Hosts of different sexes may differ in feeding habits and the composition of the skin, and thus acquire parasites differentially. Hosts of different age may be differentially infected due to accumulation of parasites with age, loss of parasites due to developing resistance (or immunity), and different size and feeding habits. Among ultimate causes of niche restriction and segregation are avoidance of competition, predation and hyperparasites; facilitation of mating; reinforcement of reproductive barriers; and adaptations to environmental complexity. Few studies permit a decision on which factor or factors are responsible in particular cases. Interspecific competition may play a greater role in helminth communities of some host groups than of others, but it seems that, overall, its role has been exaggerated at least for marine parasites. Some ‘classical’ examples of microhabitat segregation explained by interspecific competition can also be explained by reinforcement of reproductive barriers. There is evidence for the importance of facilitation of mating in microhabitat restriction, and the availability of many vacant niches indicates that competition, overall, is not of great importance.

Gastric Nematode Communities in Lizards From the Great Victoria Desert, and an Hypothesis for Their Evolution

1995 ◽  
Vol 43 (2) ◽  
pp. 141 ◽  
Author(s):  
HI Jones
Keyword(s):  
Host Species ◽  
Species Abundance ◽  
Nematode Species ◽  
Geographical Range ◽  
Infection Prevalence ◽  
Intermediate Hosts ◽  
Epidemiological Evidence ◽  
Lizard Species ◽  
Evolutionary Phase ◽  
Paratenic Hosts

This study examines the biology of gastric nematodes in two communities of lizards from the Great Victoria Desert, and develops an hypothesis for their evolution. Abbreviata antarctica A. hastaspicula, A, levicauda, A. tumidocapitis, Skrjabinoptera goldmanae, Kreisiella chrysocampa, Physalopteroides filicauda, Wanaristrongylus ctenoti and W. papangawurpae were recovered from 3023 lizards of 45 species from two different habitats. Genera in the Physalopterinae (Abbreviata, Skrjabinoptera and Kreisiella) exhibited narrow host specificities, Abbreviara and Skrjabinoptera occurring as adults only in larger host species (Varanus gouldii, V. tristis and Pogona minor). P. filicauda and encysted larvae of Physalopterinae occurred widely in the smaller lizard species in all five families represented. Eight of the nine nematode species were recovered from both lizard populations, and differences in prevalence and number of host species infected are discussed in terms of core hosts providing an infective pool. Associations were derived between parameters of infection (prevalence, intensity and abundance) and host size across and within species; abundance of nematodes in Ctenotus skinks correlated with host geographical range. Epidemiological evidence is presented that suggests that termites are intermediate hosts to species of Physalopterinae, and that Orthoptera may be intermediate hosts to P.filicauda. It is suggested that species in the Physalopterinae arose in smaller lizards (where they are now represented by the morphologically primitive Kreisiella), and that they were acquired by large predatory species by host capture, and in which they are now speciating. The small lizards now act as paratenic hosts to their larvae, and the niches left vacant have been occupied by P. filicauda. It is concluded that P.filicauda is at an early non-interactive phase and that Abbreviata and Skrjabinoptera are at an evolutionary phase, and are evolving along with their hosts. Thus, the two principal nematode groups arose at different times in response to the radiation and ecology of their hosts, and are at different stages in their own evolution.

scholarly journals Do parasites adopt different strategies in different intermediate hosts? Host size, not host species, influences Coitocaecum parvum (Trematoda) life history strategy, size and egg production

Parasitology ◽  
2012 ◽  
Vol 140 (2) ◽  
pp. 275-283 ◽  
Author(s):  
R. RUIZ DANIELS ◽  
S. BELTRAN ◽  
R. POULIN ◽  
C. LAGRUE
Keyword(s):  
Host Species ◽  
Egg Production ◽  
Life History Strategy ◽  
Host Size ◽  
Life Strategy ◽  
Amphipod Species ◽  
Intermediate Hosts ◽  
Host Interactions ◽  
Resource Limitations ◽  
Coitocaecum Parvum

SUMMARYHost exploitation induces host defence responses and competition between parasites, resulting in individual parasites facing highly variable environments. Alternative life strategies may thus be expressed in context-dependent ways, depending on which host species is used and intra-host competition between parasites. Coitocaecum parvum (Trematode) can use facultative progenesis in amphipod intermediate hosts, Paracalliope fluviatilis, to abbreviate its life cycle in response to such environmental factors. Coitocaecum parvum also uses another amphipod host, Paracorophium excavatum, a species widely different in size and ecology from P. fluviatilis. In this study, parasite infection levels and strategies in the two amphipod species were compared to determine whether the adoption of progenesis by C. parvum varied between these two hosts. Potential differences in size and/or egg production between C. parvum individuals according to amphipod host species were also investigated. Results show that C. parvum life strategy was not influenced by host species. In contrast, host size significantly affected C. parvum strategy, size and egg production. Since intra-host interactions between co-infecting parasites also influenced C. parvum strategy, size and fecundity, it is highly likely that within-host resource limitations affect C. parvum life strategy and overall fitness regardless of host species.

scholarly journals Cormorant pellets as a tool for the knowledge of parasite-intermediate host associations and nematode diversity in the environment

2019 ◽  
Vol 56 (4) ◽  
pp. 296-302 ◽  
Author(s):  
L. Garbin ◽  
J. I. Diaz ◽  
A. Morgenthaler ◽  
A. Millones ◽  
L. Kuba ◽  
...  
Keyword(s):  
Prey Item ◽  
Feeding Habits ◽  
Paratenic Host ◽  
Intermediate Hosts ◽  
Good Tool ◽  
Larval Stages ◽  
Nematode Diversity ◽  
Bird Colonies ◽  
Prey Items ◽  
Host Associations

SummaryAnisakids are usually acquired through the diet. Cormorant pellets are useful to detect both parasite larval stages, and prey items which could act as intermediate hosts in the environment. The current study provides information about the feeding habits of both birds and mammals, and the diversity of parasites circulating in the environment. The objective of the study was to identify Anisakidae larvae and prey items in pellets from the Imperial shag Phalacrocorax atriceps and the Red-legged cormorant P. gaimardi, suggesting possible parasite–prey associations. A total of 92 P. atriceps’ and 82 P. gaimardi’s pellets were collected from both Punta León, and Isla Elena bird colonies, respectively, during the period from 2006 to 2010. Pellets were preserved in ethanol and hard prey item remnants, and nematode larvae were studied using standard techniques. Prey item occurrence, nematode prevalence, and mean intensity were calculated. A correspondence analysis was performed to evaluate the larvae-prey association. Contracaecum spp., Pseudoterranova spp,, Anisakis spp., Terranova spp., and Hysterothylacium spp. third-stage larvae (L3) were identifi ed in pellets. Pseudoterranova spp. and Anisakis spp. L3 predominated in the environment of Punta León, whereas Contracaecum spp. and Hysterothylacium spp. L3 predominated in the Puerto Deseado area. The highest larvae-prey association was that of Contracaecum spp. L3 with Engraulis anchoita, followed by with Odontestes sp. in P. atriceps’ pellets. Contracaecum spp. L3 were significantly related to both sprats, Sprattus fueguensis and Ramnogaster arcuatta, in P. gaimardi’s pellets. It was verifi ed that E. anchovy is the main gateway of Contracaecum spp. L3 in P. atriceps. Odonthestes sp. might act as an intermediate/paratenic host of Contracaecum spp. L3 in the area. Both sprats might play a role as intermediate/paratenic hosts of C. australe, being the main gateway into P. gaimardi in the area. Thus, pellet analysis can be postulated as a good tool for indicating parasite-host associations between anisakids, and the prey items which act as intermediate hosts.

The influence of second intermediate host species on the infectivity of metacercarial cysts of Echinoparyphium recurvatum

1999 ◽  
Vol 73 (2) ◽  
pp. 143-145 ◽  
Author(s):  
A.M. McCarthy
Keyword(s):  
Intermediate Host ◽  
Definitive Host ◽  
Host Species ◽  
Post Infection ◽  
Rana Temporaria ◽  
Biomphalaria Glabrata ◽  
Reproductive Status ◽  
Intermediate Hosts ◽  
Potential Influence ◽  
Second Intermediate Host

The potential influence of second intermediate host species on the infectivity of metacercarial cysts of Echinoparyphium recurvatum to the definitive host Anas platyrhynchos was examined experimentally. Echinoparyphium recurvatum metacercarial cysts were obtained from the following experimentally infected second intermediate hosts 14 days post expsoure to cercariae: Lymnaea peregra; Physa fontinalis; L. stagnalis;Planorbis planorbis; Biomphalaria glabrata; tadpoles of the amphibian Rana temporaria. Metacercarial cysts from each of these hosts were fed, in doses of 50 cysts per individual, to separate groups composed of between four and eight, 3-day-old A. platyrhynchos ducklings. All A. platyrhynchos were necropsied 15 days post-infection and the number, size, and reproductive status of E. recurvatum worms in the intestine was recorded. Analyses of variance on the number (transformed log (x + 1)) and size of worms revealed no significant differences in worms originating from metacercariae formed in the different second intermediate hosts (worm number P > 0.05, and worm size P > 0.05). All worms recovered were found to be gravid. It is therefore concluded that the species of second intermediate host utilized does not influence the infectivity of the metacercarial cyst of E. recurvatum, nor the subsequent establishment and reproductive status of the parasite in A. platyrhynchos.

Specificity

2021 ◽  
pp. 159-182
Author(s):  
Paul Schmid-Hempel
Keyword(s):  
Host Range ◽  
Host Species ◽  
Cross Reactivity ◽  
Geographical Range ◽  
Immune Memory ◽  
Phylogenetic Distance ◽  
Immune Priming ◽  
Number Of Factors ◽  
Ecological Filter ◽  
Immune Defences

infect a number of host species. This host range is given by an ecological filter (the possibility of encounter) and a physiological one (the capacity of establishing an infection). Host ranges typically are right-skewed, with most parasites infecting only a few, but few infecting very many hosts. There is no universally valid hypothesis that explains host range. However, a number of factors contribute to host range, such as geographical range, phylogenetic distance, host predictability, and parasite virulence. Specificity and cross-reactivity of immune defences are important mechanisms. Moreover, immune memory is based on specificity; transgenerational immune priming protects offspring when parents have already been exposed to the same or similar parasites.

scholarly journals Toxoplasma gondii antibodies and related risk factors in mammals at Sorocaba zoo, São Paulo, BrazilToxoplasma gondii antibodies and related risk factors in mammals at Sorocaba zoo, São Paulo, Brazil

2017 ◽  
Vol 38 (4Supl1) ◽  
pp. 2845
Author(s):  
Renata Bezerra Marujo ◽  
Helio Langoni ◽  
Leila Sabrina Ullmann ◽  
Maysa Pellizzaro ◽  
Ramiro Das Neves Dias Neto ◽  
...  
Keyword(s):  
Risk Factors ◽  
Toxoplasma Gondii ◽  
Feeding Habits ◽  
Univariate Analysis ◽  
Multivariate Logistic Regression Analysis ◽  
Sao Paulo ◽  
São Paulo ◽  
Intermediate Hosts ◽  
Serum Samples ◽  
Related Risk

Toxoplasmosis is a parasitic zoonosis with worldwide distribution and different wild species either are involved in maintenance of the pathogen in the environment as definitive or intermediate hosts serving as font of feeding or prey to definitive hosts. The present study aimed to investigate Toxoplasma gondii antibodies and the risk factors relating to infection in mammals at Sorocaba Zoo, state of São Paulo, Brazil. Serum samples collected from 153 animals were analyzed using the modified agglutination test (MAT; cutoff ? 25). Seropositivity was found in 62 animals (40.5%; 95% CI: 33.1-48.5%), with different titers. Significant differences were observed in relation to the ages of the animals, origin, presence of free-ranging animals in the enclosure and feeding habits, through univariate analysis (p ? 0.05). Multivariate logistic regression analysis showed that only age (p = 0.03) had significance for the study. Adult animals were 3.5 more likely to become infected than were young ones. In relation to feeding habits, herbivores (80%) and carnivores (46.5%) were the animals most affected. These results highlight the presence of T. gondii in animals at Brazilian zoos, and suggest that continuous transmission is occurring at zoos.

Observations on the suitability and importance of the domestic intermediate hosts of Echinococcus granulosus in Uttah Pradesh, India

1989 ◽  
Vol 63 (1) ◽  
pp. 39-45 ◽  
Author(s):  
M. Irshadullah ◽  
W. A. Nizami ◽  
C. N. L. Macpherson
Keyword(s):  
Life Cycle ◽  
Intermediate Host ◽  
Echinococcus Granulosus ◽  
Frequency Distribution ◽  
Host Species ◽  
Control Measures ◽  
The Other ◽  
Hydatid Cysts ◽  
Intermediate Hosts ◽  
Cyst Size

ABSTRACTThe present study investigated the suitability and importance of buffaloes, camels, sheep, goats and pigs in maintaining the life-cycle of Echinococcus granulosus in Aligarh, India. A total of 565 (36%) of 1556 buffaloes, 20 (2%) of 1208 goats, 5 (1%) of 559 pigs, 6 (6%) of 109 sheep and two of three camels were found to harbour hydatid cysts. The frequency distribution of the hydatid cysts in each intermediate host species was over-dispersed and in buffaloes cyst fertility increased with increasing cyst size. Of 2171, 95 and four buffalo, goat, and camel cysts examined 327 (15%), two (2%) and three cysts respectively were fertile. No pig or sheep cysts were found to contain protoscoleces. The unfenced buffalo abattoir and the large number of dogs allowed access to the abattoir coupled to the number of buffaloes slaughtered in comparison to the other potential hosts, indicates that the buffalo is the most significant host for maintaining the life-cycle of the parasite in this area of India. Applicable control measures for the region are suggested.

The evolution of tissue migration by parasitic nematode larvae

Parasitology ◽  
1995 ◽  
Vol 111 (3) ◽  
pp. 359-371 ◽  
Author(s):  
A. F. Read ◽  
A. Sharping
Keyword(s):  
Natural Selection ◽  
Life History Strategy ◽  
Skin Penetration ◽  
Intermediate Hosts ◽  
Nematode Larvae ◽  
Morphological Adaptations ◽  
Juvenile Habitat ◽  
Tissue Migration ◽  
Adult Habitat ◽  
Tissue Phase

SUMMARYMigration by nematode larvae through the tissues of their mammalian hosts can cause considerable pathology, and yet the evolutionary factors responsible for this migratory behaviour are poorly understood. The behaviour is particularly paradoxical in genera such as Ascaris and Strongylus in which larvae undergo extensive migrations which begin and end in the same location. The orthodox explanation for this apparently pointless behaviour is that a tissue phase is a developmental requirement following the evolutionary loss of skin penetration or intermediate hosts. Yet tissue migration is not always necessary for development, and navigation and survival in an array of different habitats must require costly biochemical and morphological adaptations. Migrating larvae also risk becoming lost or killed by the host. Natural selection should therefore remove such behaviour unless there are compensating benefits. Here we propose that migration is a selectively advantageous life-history strategy. We show that taxa exploiting tissue habitats during development are, on average, bigger than their closest relatives that develop wholly in the gastrointestinal tract. Time to reproduction is the same, indicating that worms with a tissue phase during development grow faster. This previously unsuspected association between juvenile habitat and size is independent of any effects of adult habitat, life-cycle, or host size, generation time or diet. Because fecundity is intimately linked with size in nematodes, this provides an explanation for the maintenance of tissue migration by natural selection, analogous to the pre-spawning migrations of salmon.

The occurrence of Anisakis sp. type I larvae (Oshima 1972) (Nematoda: Anisakidae) in fishes from the Gulf of Alaska and the Bering Sea

1983 ◽  
Vol 61 (1) ◽  
pp. 266-268 ◽  
Author(s):  
G. J. Munger
Keyword(s):  
Bering Sea ◽  
Feeding Habits ◽  
Gulf Of Alaska ◽  
Type I ◽  
Intermediate Hosts ◽  
Bristol Bay ◽  
The Bering Sea

Of 33 species of fish examined for Anisakis larvae, 12 (36%) were infected. Larvae were identified as Anisakis type I larvae (Oshima 1972) and were found in fish from all localities surveyed: Bristol Bay, Unimak, Chirikof, Chiniak, and Cape St. Elias. The small size and feeding habits of some fish infected suggests that small fishes or very small invertebrates rather than euphausids may be the intermediate hosts for Anisakis type I larvae.

Abundance/host size relationship in a fish trematode community

1992 ◽  
Vol 66 (3) ◽  
pp. 187-192 ◽  
Author(s):  
A. Saad-Fares ◽  
C. Combes
Keyword(s):  
Interspecific Competition ◽  
Digestive Tract ◽  
Host Species ◽  
Size Class ◽  
Host Size ◽  
Trematode Species ◽  
High Threshold ◽  
East Mediterranean ◽  
Host Growth ◽  
Single Host

ABSTRACTThe abundance of six species of trematodes: Aphanurus stossichi, Bacciger israelensis, Diphterostomum israelense, Plagioporus idoneus, Lepocreadium album and L. pegorchis, parasitic in the digestive tract of marine teleostei (Sparidae) collected near Jounieh (east Mediterranean), was analysed as a function of the host-size. In two parasite/host systems, infections were observed from the lowest size classes of the sample, with a clear tendency to an increase of abundance in older fish. In four others, parasites appear only above a rather high threshold class, young individuals never being infected. In the last three parasite/host systems, host invasion may occur early or late, but infection decreases above a well defined size class, old fishes rarely or never being infected. A given trematode species. when parasitizing several host species, shows similar abundance/host size relationships, e.g. P. idoneus in Diplodus vulgaris and Oblada melanura. When more than one species of trematode infects a single host species, curves can be markedly distinct; for instance, L. pegorchis was collected from Pagellus erythrinus below 15 cm. whereas D. israelense parasitized the same fish approximately above the same size. There is no evidence that such a replacement of one trematode by another in the course of host growth is a result of interspecific competition.

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