Body size evolution of oxyurid (Nematoda) parasites: the role of hosts

Morand, Sergé; Legendre, Pierre; Gardner, Scott Lyell; Hugot, Jean‐Pierre

doi:10.1007/bf00327912

Cited by 73 publications

(61 citation statements)

References 35 publications

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“…Morand et al (1996) hypothesized and confirmed in the case of endoparasites that long-lived hosts provide more energy and could harbor more long-lived and larger parasites. Therefore, host longevity could represent the predictability connected with specialization.…”

Section: Determinants Of Host Specificitymentioning

confidence: 69%

Specificity and Specialization of Congeneric Monogeneans Parasitizing Cyprinid Fish

et al. 2006

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Abstract. Patterns and likely processes connected with evolution of host specificity in congeneric monogeneans parasitizing fish species of the Cyprinidae were investigated. A total of 51 Dactylogyrus species was included. We investigated (1) the link between host specificity and parasite phylogeny; (2) the morphometric correlates of host specificity, parasite body size, and variables of attachment organs important for host specificity; (3) the evolution of morphological adaptation, that is, attachment organ; (4) the determinants of host specificity following the hypothesis of specialization on more predictable resources considering maximal body size, maximal longevity, and abundance as measures of host predictability; and (5) the potential link between host specificity and parasite diversification. Host specificity, expressed as an index of host specificity including phylogenetic and taxonomic relatedness of hosts, was partially associated with parasite phylogeny, but no significant contribution of host phylogeny was found. The mapping of host specificity into the phylogenetic tree suggests that being specialist is not a derived condition for Dactylogyrus species. The different morphometric traits of the attachment apparatus seem to be selected in connection with specialization of specialist parasites and other traits favored as adaptations in generalist parasites. Parasites widespread on several host species reach higher abundance within hosts, which supports the hypothesis of ecological specialization. When separating specialists and generalists, we confirmed the hypothesis of specialization on a predictable resource; that is, specialists with larger anchors tend to live on fish species with larger body size and greater longevity, which could be also interpreted as a mechanism for optimizing morphological adaptation. We demonstrated that ecology of host species could also be recognized as an important determinant of host specificity. The mapping of morphological characters of the attachment organ onto the parasite phylogenetic tree reveals that morphological evolution of the attachment organ is connected with host specificity in the context of fish relatedness, especially at the level of host subfamilies. Finally, we did not find that host specificity leads to parasite diversification in congeneric monogeneans.

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Section: Determinants Of Host Specificitymentioning

confidence: 69%

Specificity and Specialization of Congeneric Monogeneans Parasitizing Cyprinid Fish

et al. 2006

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“…Trouv e et al, 2003;Randhawa & Poulin, 2009;Benesh et al, 2013) and nematodes (e.g. Harvey & Keymer, 1991;Morand et al, 1996;Arneberg et al, 1998) show the expected positive relation between adult helminth size and definitive host body size, acanthocephalans show this pattern only weakly when corrected for phylogeny , and trematodes only when uncorrected for phylogeny (Poulin, 1997(Poulin, , 2007. Further trematode puzzles include failure to find an egg size-number trade-off (Poulin, 1997; but see Loker, 1983), and their similar growth patterns in ectotherm and endotherm definitive hosts (Poulin & Latham, 2003).…”

Section: Future Prospectsmentioning

confidence: 99%

Evolution of complex life cycles in trophically transmitted helminths. I. Host incorporation and trophic ascent

Parker

Ball

Chubb

2015

J of Evolutionary Biology

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Links between parasites and food webs are evolutionarily ancient but dynamic: life history theory provides insights into helminth complex life cycle origins. Most adult helminths benefit by sexual reproduction in vertebrates, often high up food chains, but direct infection is commonly constrained by a trophic vacuum between free-living propagules and definitive hosts. Intermediate hosts fill this vacuum, facilitating transmission to definitive hosts. The central question concerns why sexual reproduction, and sometimes even larval growth, is suppressed in intermediate hosts, favouring growth arrest at larval maturity in intermediate hosts and reproductive suppression until transmission to definitive hosts? Increased longevity and higher growth in definitive hosts can generate selection for larger parasite body size and higher fecundity at sexual maturity. Life cycle length is increased by two evolutionary mechanisms, upward and downward incorporation, allowing simple (one-host) cycles to become complex (multihost). In downward incorporation, an intermediate host is added below the definitive host: models suggest that downward incorporation probably evolves only after ecological or evolutionary perturbations create a trophic vacuum. In upward incorporation, a new definitive host is added above the original definitive host, which subsequently becomes an intermediate host, again maintained by the trophic vacuum: theory suggests that this is plausible even under constant ecological/evolutionary conditions. The final cycle is similar irrespective of its origin (upward or downward). Insights about host incorporation are best gained by linking comparative phylogenetic analyses (describing evolutionary history) with evolutionary models (examining selective forces). Ascent of host trophic levels and evolution of optimal host taxa ranges are discussed.

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“…In fact, we pointed out a significant correlation between host cell size and the final parasite size. This phenomenon, currently observed in parasitology (39)(40)(41), has been reported just once in the context of the fungal parasitism of phytoplankton (17). Chytrids, like some other parasites, feed on the contents of their host (3), and so their development and final size are closely dependent on these contents.…”

Section: Discussionmentioning

confidence: 75%

A Double Staining Method Using SYTOX Green and Calcofluor White for Studying Fungal Parasites of Phytoplankton

Gerphagnon

Latour

Colombet

et al. 2013

Appl Environ Microbiol

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We propose a double staining method based on the combination of two fluorochromes, calcofluor white (CFW; specific chitinous fluorochrome) and SYTOX green (nucleic acid stain), coupled to epifluorescence microscopy for counting, identifying, and investigating the fecundity of parasitic fungi of phytoplankton and the putative relationships established between hosts and their chytrid parasites. The method was applied to freshwater samples collected over two successive years during the terminal period of autumnal cyanobacterial blooms in a eutrophic lake. The study focused on the uncultured host-parasite couple Anabaena macrospora (cyanobacterium) and Rhizosiphon akinetum (Chytridiomycota). Our results showed that up to 36.6% of cyanobacterial akinetes could be parasitized by fungi. Simultaneously, we directly investigated the zoosporic content inside the sporangia and found that both the host size and intensity of infection conditioned the final size and hence fecundity of the chytrids. We found that relationships linking host size, final parasite size, and chytrid fecundity were conserved from year to year and seemed to be host-chytrid couple specific. We concluded that our double staining method was a valid procedure for improving our knowledge of uncultured freshwater phytoplankton-chytrid couples and so of the quantitative ecology of chytrids in freshwater ecosystems. Many phytoplankton species are susceptible to fungal parasitism. In freshwater lakes, the main parasitic zoosporic fungi belong to the Chytridiomycota (i.e., chytrids). Recent advances in molecular biology have revealed unsuspected fungal diversity in the small size fraction (0.6 to 5 m) (1), which comprises the dissemination form (i.e., zoospores). Microscopic studies of the reproductive stages of chytrids (i.e., the sporangium) have also revealed the wide diversity of chytrid species in the pelagic zone occurring in lakes throughout the year (2). Chytrids, like some other parasites, are completely dependent on their host for their nourishment and their development, which results in the death of their host (3). Previous studies focused on the impact of fungal parasitism on phytoplankton dynamics and have highlighted the fact that fungal parasitism has had a real impact on the decline of several eukaryotic phytoplankton species, showing that fungal parasitism is potentially implicated in the phytoplankton succession (4-10).The prevalence and intensity of infection constitute the two parameters classically used to estimate the ecological impacts of fungal parasitism on phytoplankton (11, 12). However, it has been recognized that zoospores are an important source of carbon in freshwater ecosystems and act as a real link between inedible host algae and higher trophic levels (4,8). It is therefore surprising to find that the accurate quantification of chytrid fecundity (i.e., number of zoospores per sporangium), a key parameter in chytrid life cycles, is often omitted in field studies. As far as we are aware, no study has directly investigated the cl...

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Body size evolution of oxyurid (Nematoda) parasites: the role of hosts

Cited by 73 publications

References 35 publications

Specificity and Specialization of Congeneric Monogeneans Parasitizing Cyprinid Fish

Specificity and Specialization of Congeneric Monogeneans Parasitizing Cyprinid Fish

Evolution of complex life cycles in trophically transmitted helminths. I. Host incorporation and trophic ascent

A Double Staining Method Using SYTOX Green and Calcofluor White for Studying Fungal Parasites of Phytoplankton

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