Pairing Probability of Schistosomes Related to Their Distribution Among the Host Population

Morand, Serge; Pointier, Jean‐Pierre; Borel, G.; Thèron, André

doi:10.2307/1939595

Cited by 33 publications

(31 citation statements)

References 13 publications

(21 reference statements)

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“…Average worm counts per mouse (Table 1) did not significantly differ between strains (Welch two-sample t-test p ≥ 0.5 for all comparisons). As has been reported previously (Mitchell et al, 1990; Morand et al, 1993), the observed sex ratio of worms was biased toward males. The lower male worm sex ratio observed in the CF1 strain was not significant (Pearson’s Chi-squared test p > 0.1 for CF1 vs. all other strains).…”

supporting

confidence: 88%

Host Mouse Strain Is Not Selective for a Laboratory Adapted Strain of Schistosoma mansoni

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Liu

Prasad

et al. 2011

Journal of Parasitology

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We genotyped pooled adult worms of Schistosoma mansoni from infected CF1, C57BL/6, BALB/c, and BALB/c interferon gamma knockout mice in order to investigate if mouse strain differences selected for parasite genotypes. We also compared differentiation in eggs collected from liver and intestines to determine if there was differential distribution of parasite strains in the vertebrate host that might account for any genotype selection. We found that mouse strains with differing immune responses did not differ in resistance to infection and did not select for parasite genotypes. S. mansoni genotypes were also equally distributed in tissues and there was no difference between adult and egg allele frequencies. Differing immune responses in these mouse strains does not significantly affect the degree or the nature of host resistance to schistosomes.

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supporting

confidence: 88%

Host Mouse Strain Is Not Selective for a Laboratory Adapted Strain of Schistosoma mansoni

Blank

Liu

Prasad

et al. 2011

Journal of Parasitology

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“…First, the presence of clones (identical MLGs) in a definitive host may affect genetic sex ratios because the sex ratio in terms of number of unique male and female MLGs may be quite different than the sex ratio observed from the total number of males and females in a host. The evolution of sex ratio in schistosomes is interesting because biased sex ratios increase sexual competition (May and Woolhouse, 1993; Morand et al, 1993; Morand and Müller-Graf, 2000) and reduce the effective number of breeders per definitive host (Criscione and Blouin, 2005). A second way in which clones can influence mating systems is that even if worm pairs remain monogamous throughout their lifetime, the occurrence of multiple individuals of the same clone can result in genetic half-sibships (Fig 2).…”

Section: Mating Systemsmentioning

confidence: 99%

Applying evolutionary genetics to schistosome epidemiology

Steinauer¹,

Blouin²,

Criscione³

2010

Infection, Genetics and Evolution

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We review how molecular markers and evolutionary analysis have been applied to the study of schistosome parasites, important pathogens that infect over 200 million people worldwide. Topics reviewed include phylogenetics and biogeography, hybridization, infection within snails, mating systems, and genetic structure. Some interesting generalizations include that schistosome species hybridize frequently and have switched definitive hosts repeatedly in evolutionary time. We show that molecular markers can be used to infer epidemiologically-relevant processes such as spatial variation in transmission, or to reveal complex patterns of mate choice. Analysis of genetic structure data shows that transmission foci can be structured by watershed boundaries, habitat types, and host species. We also discuss sampling and analytical problems that arise when using larvae to estimate genetic parameters of adult schistosome populations. Finally, we review pitfalls in methodologies such as genotyping very small individuals, statistical methods for identifying clonemates or for identifying sibling groups, and estimating allele frequencies from pooled egg samples.

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“…The majority of these parasite populations worldwide appear to have a male‐biased sex ratio, particularly in early stages of infection (Morand et al. ). Empirically, the broad agreement that male‐biased adult sex ratios can explain male monogamy is complemented by cases where female‐biased ASRs are used to explain male roaming (Berger‐Tal and Lubin ).…”

mentioning

confidence: 99%

Understanding Promiscuity: When Is Seeking Additional Mates Better Than Guarding an Already Found One?

Harts

Kokko

2013

Evolution

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Paternity protection and the acquisition of multiple mates select for different traits. The consensus from theoretical work is that mate-guarding intensifies with an increasing male bias in the adult sex ratio (ASR). A male bias can thus lead to male monogamyif guarding takes up the entire male time budget. Given that either female-or male-biased ASRs are possible, why is promiscuity clearly much more common than male monogamy? We address this question with two models, differing in whether males can assess temporal cues of female fertility. Our results confirm the importance of the ASR: guarding durations increase with decreasing female availability and increasing number of male competitors. However, several factors prevent the mating system from switching to male monogamy as soon as the ASR becomes male biased. Inefficient guarding, incomplete last male sperm precedence, any mechanism that allows sperm to fertilize eggs after the male's departure, and (in some cases) the unfeasibility of precopulatory guarding all help explain cases where promiscuity exists on its own or alongside temporally limited mate-guarding. Shortening the window of fertilization shifts guarding time budgets from the postcopulatory to the precopulatory stage. K E Y W O R D S :Male mating strategy, mate-guarding, monogamy, paternity protection, sex ratio.A simplified view of mating systems and sex differences in reproductive strategies often emphasizes sex differences in the optimal rate of mating, typically higher for males than for females (Gavrilets 2000;Arnqvist and Rowe 2005;Maklakov et al. 2005;Gavrilets and Hayashi 2006). Such a difference cannot, however, explain those monogamous situations that are based on male strategies of paternity protection, which can take the form of extensive mate-guarding (Beecher and Beecher 1979;Birkhead 1979) or mating plugs (Baer et al. 2001;Foellmer 2008;Fromhage 2012). In these cases, it appears to be in the best interest of a male to achieve high paternity with one or few females, rather than attempt maximally many matings.Clearly, paternity protection and the acquisition of multiple mates can select for different traits. In extreme cases of terminal investment, paternity protection can mean that a male foregoes all chances of finding another female (Fromhage et al. 2005). Mateguarding, which we focus on here (defined as the close association between a male and female prior to and/or after copulation for paternity assurance), does not always have to be that extreme. Still, there is often a direct trade-off involving time: guarding one female often effectively prevents a male from searching for more of them (Birkhead and Møller 1992;Dickinson 1995;Simmons and Siva-Jothy 1998;Fryer et al. 1999). It follows that if mateguarding becomes sufficiently extended over time, the mating system becomes socially monogamous (Mathews 2002; note that a socially monogamous system can be genetically monogamous too, if guarding is efficient enough).Past research has outlined a few principles of whether males should s...

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Pairing Probability of Schistosomes Related to Their Distribution Among the Host Population

Cited by 33 publications

References 13 publications

Host Mouse Strain Is Not Selective for a Laboratory Adapted Strain of Schistosoma mansoni

Host Mouse Strain Is Not Selective for a Laboratory Adapted Strain of Schistosoma mansoni

Applying evolutionary genetics to schistosome epidemiology

Understanding Promiscuity: When Is Seeking Additional Mates Better Than Guarding an Already Found One?

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