Causes of inter-individual variation in reproductive strategies of the parasitic nematode Graphidioides subterraneus

Rossin, María Alejandra; Poulin, Robert; Timi, Juan T.; Malizia, Ana I.

doi:10.1007/s00436-005-1400-0

Cited by 16 publications

(20 citation statements)

References 24 publications

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“…Concerning clutch size variation in laying females we found that the number of laid eggs was partly explained by body size (females with larger thorax and wider abdomen laid more eggs), as expected from the generally accepted relationship between body size and fecundity (Fox and Czesak 2000;Branquart and Hemptinne 2000;Rossin et al 2005). However, we also found a negative relationship between abdomen length and number of laid eggs.…”

Section: Discussionsupporting

confidence: 62%

“…The aims of our study are: (1) to provide basic information on the reproductive anatomy and fecundity of C. hemapterus, (2) to assess the validity of an experimental method to estimate fecundity in this species, (3) to explore whether the general relationship between body size and fecundity (Fox and Czesak 2000;Branquart and Hemptinne 2000;Rossin et al 2005) is applicable in C. hemapterus.…”

Section: Introductionmentioning

confidence: 99%

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Reproductive anatomy and fecundity estimation of the haematophagous ectoparasite Carnus hemapterus

Valera

Zídková

2011

Parasitol Res

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The dynamics of host-parasite interactions depends to a large extent on the effect of host responses on parasite fitness. An increased research effort is currently being invested in the study of host influence on parasite fitness both at a population and at an individual level even though basic information (e.g. the reproductive anatomy of parasites) is frequently missing. Here, we study for the first time the reproductive system of the diptera Carnus hemapterus, a 2-mm long, highly mobile haematophagous fly parasitizing nestlings of a broad variety of bird species. Although this species is poorly known, it is being increasingly used for the study of host-parasite interactions. We also assess the reliability of a method to estimate fecundity based on the number of laid eggs per gravid female and analyse the effect of body size on fecundity estimates. Our results show that carnid flies are synovigenic, so that both the number of laid eggs at a given moment and the egg load represent only a fraction of the true potential fecundity. Moreover, laid eggs are probably a fraction of the number of mature eggs ready to be laid since females withheld seemingly mature eggs at oviposition. A high proportion of pregnant females did not lay eggs, and the number of eggs laid per pregnant female varied remarkably. The latter is explained partly by a positive relationship with body size (thorax length and abdomen width). Caution is needed when using the number of laid eggs as a shortcut estimation of fecundity in C. hemapterus. We propose some improvements to the method for assessing Carnus fertility.

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Section: Discussionsupporting

confidence: 62%

Section: Introductionmentioning

confidence: 99%

Reproductive anatomy and fecundity estimation of the haematophagous ectoparasite Carnus hemapterus

Valera

Zídková

2011

Parasitol Res

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“…For example, a myriad of factors affect the reproductive resources available to individual parasites, such as host suitability, host diet and intra-and inter-specific competition (Boddington & Mettrick, 1981;Holland, 1984;Dobson, 1986;Crompton et al, 1988;Shostak & Scott, 1993;Marcogliese, 1997). Parental quality may be translated into variation in egg size or quantity, traits known to vary intraspecifically in parasites (Rossin et al, 2005;Herreras et al, 2007). Fine-tuned, adaptive parental effects can evolve when the adult environment gives cues about the environment of larval parasites.…”

Section: Introductionmentioning

confidence: 99%

Parental effects on the larval performance of a tapeworm in its copepod first host

Benesh

2013

J of Evolutionary Biology

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Parents can influence the phenotype of their offspring through various mechanisms, besides the direct effect of heredity. Such parental effects are little explored in parasitic organisms, perhaps because in many parasites, per capita investment into offspring is low. I investigated whether parental identity, beyond direct genetic effects, could explain variation in the performance of the tapeworm Schistocephalus solidus in its first intermediate host, a copepod. I first determined that two breeding worms could be separated from one another after~48 h of in vitro incubation and that the isolated worms continued producing outcrossed eggs, that is, rates self-fertilization did not increase after separation. Thus, from a breeding pair, two sets of genetically comparable eggs can be collected that have unambiguous parental identities. In an infection experiment, I found that the development of larval worms tended to vary between the two parental worms within breeding pairs, but infection success and growth rate in copepods did not. Accounting for this parental effect decreased the estimated heritability for development by nearly half. These results suggest that larval performance is not simply a function of a worm's genotype; who mothered or fathered an offspring can also affect offspring fitness, contradicting the perhaps na€ ıve idea that parasites simply produce large quantities of uniformly low-quality offspring.

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“…A phenotypic tradeoff between propagule number and propagule size within a given population is considered to occur when these two traits are negatively correlated but very often this pattern is not observed in nature (Roff 1992, 2002, Stearns 1992, Bernardo 1996. Indeed, it has not been found in the two parasite populations studied to date (Rossin et al 2005, Timi et al 2005, but note that failure to reveal phenotypic tradeoffs does not necessarily ensure their absence. In a seminal paper, van Noordwijk and de Jong (1986) developed a model to illustrate how individual differences in acquisition and allocation of resources can explain why underlying tradeoffs may go unnoticed.…”

mentioning

confidence: 99%

Phenotypic tradeoffs between egg number and egg size in three parasitic anisakid nematodes

Herreras¹,

Montero²,

Marcogliese³

et al. 2007

Oikos

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Phenotypic tradeoffs between number and size of eggs were tested in three component populations of three marine anisakid nematodes: Anisakis simplex , Pseudoterranova decipiens and Contracaecum osculatum . Body and uterine volumes (as proxies of female size), and egg number, mean egg volume and clutch volume (as descriptors of reproductive output) were measured in 50 females of each species. Evidence of a phenotypic tradeoff was detected only in A. simplex ; the first time that has been found in a parasite population. Comparison of feasible values inferred from the van Noordwijk and de Jong's model and current data showed that interindividual variation in egg size was narrower than expected in the three populations. Structural constrictions in response to optimal allocation rules might account for this pattern. In P. decipiens and C. osculatum variation in egg size was the lowest and independent of female size, suggesting that the tradeoff is absent, rather than being present but masked by unaccounted variables. Spatial constrictions imposed by uterine size seemed to play an important role determining the emergence of the tradeoffs. So factors accounting for the tradeoff in A. simplex are probably constructional rather than physiological. Individual variability in investment in clutch volume was similar to previous studies but variation in allocation between number and size of eggs was much smaller than that reported previously. Perhaps differences in life-history strategies might explain this because the nematodes studied are either semelparous or short-lived iteroparus organisms whereas previous data derive from long-lived iteroparous ones. Despite the perception that parasites live in resource-rich habitats, the present study indicates that patterns relating number and size of eggs might not differ much from those observed in free-living populations and thus the same range of factors would operate in both types of organisms.The reproductive output of any individual can be partitioned into two components, propagule number and propagule size. The relationship between them is still poorly known in parasites, where only two studies concerning Graphidioides subterraneus , a parasitic nematode of rodents (Rossin et al. 2005), and Lernanthropus cynoscicola, a copepod parasite on fish (Timi et al. 2005), have been carried out at population level. Because both components compete directly for the limited energy budget and/or for the limited space within a mother, a tradeoff between them is expected. Previous studies (including the two of parasites mentioned above) have used correlations between number and size of eggs in order to test for the occurrence of this phenotypic tradeoff. It has been argued that this approach is of limited value because (1) it is impossible to infer causation from correlation, (2) environmental variation may mask or accentuate the correlation, and (3) phenotypic correlations do not demonstrate genetic control of the tradeoffs (Reznick 1985, Lessells et al. 1989. However, when selection acts on...

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Causes of inter-individual variation in reproductive strategies of the parasitic nematode Graphidioides subterraneus

Cited by 16 publications

References 24 publications

Reproductive anatomy and fecundity estimation of the haematophagous ectoparasite Carnus hemapterus

Reproductive anatomy and fecundity estimation of the haematophagous ectoparasite Carnus hemapterus

Parental effects on the larval performance of a tapeworm in its copepod first host

Phenotypic tradeoffs between egg number and egg size in three parasitic anisakid nematodes

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