Life History Covariation in Intestinal Nematodes of Mammals

Skorping, Arne; Read, Andrew F.; Keymer, A. E.

doi:10.2307/3545079

Cited by 104 publications

(103 citation statements)

References 48 publications

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“…This indicates that delaying reproduction is associated with large body size. Because large body size is correlated with high fecundity, a fecundity advantage is thus associated with delaying maturity as pointed out by Skorping et al (1991) and Keymer et al (1991). A similar correlation between mortality rate and age at maturity (or prepatent period) is found in both free-living and parasitic nematodes (Morand 1996b).…”

Section: Discussionmentioning

confidence: 92%

“…Some studies have tried to explain the variation of life-history according to r-K theory (Esch et al 1977) while others have emphasised the importance of trade-offs between fecundity and reproductive lifespan (Wharton 1986). The studies of Keymer et al (1991) and Skorping et al (1991) investigate the selective pressures driving the evolution of life-history traits of parasitic nematodes. Morand (1996b) investigated the evolution of life-history traits in free-living, plant, insect and vertebrate parasite nematodes.…”

Section: Discussionmentioning

confidence: 99%

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

et al. 1996

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Studying the diversification of body size in a taxon of parasites allows comparison of patterns of variation observed in the parasites with patterns found in free-living organisms. The distributions of body size of oxyurid nematodes (obligate parasites of vertebrates and invertebrates) are lognormally right-skewed, except for male oxyurids in invertebrates which show left-skewed distributions. In these parasitic forms, speciose genera do not have the smallest body sizes. Parasite body size is positively correlated with host body size, the largest hosts possessing the largest parasites. This trend is shown to occur within one monophyletic group of oxyurids, those of Old World primates. Comparative methods are used to take account of the effects of phylogeny. The use of multiple linear regression on distance matrices allows measurements of the contribution of phylogeny to the evolution of body size of parasites. Evolution of body size in female pinworms of Old World primates appears to be dependent only on the body size of their hosts. The tendency of parasite body size to increase with host body size is discussed in the light of the evolution of life-history traits.

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Section: Discussionmentioning

confidence: 92%

Section: Discussionmentioning

confidence: 99%

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

et al. 1996

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“…Furthermore, the transmission success is likely to depend on its density within the host (for microparasites) or on its size (for macroparasites). As is the case for invertebrates in general (Peters 1983), the fecundity of many helminth parasites, for example, increases with their size (Roberts 1961;Loker 1983;Skorping et al 1991;Morand 1996) and a large size may be achieved most easily in association with a large host (Orr & Hopkins 1969;Poulin 1995). We therefore extended previous models by adding sub-lethal effects to the description of the host2parasite interaction; the parasite reduces the rate at which the host grows and, in turn, the host's size limits the growth and the fitness of the parasite.…”

Section: Introductionmentioning

confidence: 99%

Sub-lethal effects of pathogens can lead to the evolution of lower virulence in multiple infections

Schjørring

Koella²

2003

Proc. R. Soc. Lond. B

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According to current evolutionary dogma, multiple infections generally increase a parasite's virulence (i.e. reduce the host's reproductive success). The basic idea is that the competitive interactions among strains of parasites developing within a single host select individual parasites to exploit their host more rapidly than their competitors (thereby causing an increase in virulence) to ensure their transmission. Although experimental evidence is scarce, it often contradicts the theoretical expectation by suggesting that multiple infections lead to decreased virulence. Here, we present a theoretical model to explain this contradiction and show that the evolutionary outcome of multiple infections depends on the characteristics of the interaction between the host and its parasite. If we assume, as current models do, that parasites have only lethal effects on their host, multiple infections indeed increase virulence. By contrast, if parasites have sub-lethal effects on their host (such as reduced growth) and, in particular, if these effects feed back onto the parasites to reduce their rate of development, then multiplicity of infection generally leads to lower virulence.

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“…Skorping et al (1991) and more recently Morand (1996) analysed life history trade-offs in 66 and 30 nematode species, including both parasitic and free-living species. These studies showed that prepatent period was positively correlated with female body length, and that prepatent period was negatively correlated with female adult mortality rate.…”

Section: Introductionmentioning

confidence: 99%

Host–parasite coevolution: comparative evidence for covariation of life history traits in primates and oxyurid parasites

Sorci

Morand

Hugot³

1997

Proc. R. Soc. Lond. B

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SUMMARYThe environmental factors that drive the evolution of parasite life histories are mostly unknown. Given that hosts provide the principal environmental features parasites have to deal with, and given that these features (such as resource availability and immune responses) are well characterized by the life history of the host, we may expect natural selection to result in covariation between parasite and host life histories. Moreover, some parasites show a high degree of host specificity, and cladistic analyses have shown that host and parasite phylogenies can be highly congruent. These considerations suggest that parasite and host life histories may covary. The central argument in the theory of life history evolution concerns the existence of trade-offs between traits. For parasitic nematodes it has been shown that larger body sizes induce higher fecundity, but this is achieved at the expense of delayed maturity. As high adult mortality would select for reduced age at maturity, the selective benefit of increased fecundity is expressed only if adult mortality is low. Parasite adult mortality may depend on a number of factors, including host longevity. Here we tested the hypothesis concerning the positive covariation between parasite body size (which reflects parasite longevity) and host longevity. To achieve this goal, we used the association between the pinworms (Oxyuridae, Nematoda) and their primate hosts. Oxyurids are highly host specific and are supposed to be involved in a coevolutionary process with their hosts. We found that female parasite body length was positively correlated with host longevity after correcting for phylogeny and host body mass. Conversely, male parasite body length and host longevity were not correlated. These results confirm that host longevity may represent a constraint on the evolution of body size in oxyurids, at least in females. The discrepancy between female and male oxyurids is likely to depend on the particular mode of reproduction of this taxon (haplodiploidy), which should result in weak (or even null) selection pressures to an increase of body size in males.

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Life History Covariation in Intestinal Nematodes of Mammals

Cited by 104 publications

References 48 publications

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

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

Sub-lethal effects of pathogens can lead to the evolution of lower virulence in multiple infections

Host–parasite coevolution: comparative evidence for covariation of life history traits in primates and oxyurid parasites

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