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Voordouw, Maarten

Nom
Voordouw, Maarten
Affiliation principale
Fonction
Ancien.ne collaborteur.trice
Identifiants
https://libra.unine.ch/handle/123456789/375
_
0000-0001-9384-0436

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  • Publication
    Accès libre
    Genetic variation in the primary sex ratio in populations of the intertidal copepod, Tigriopus californicus, is widespread on Vancouver Island
    (2008)
    Voordouw, Maarten 
    ;
    Stebbins, Gabe
    ;
    Robinson, H. Eve
    ;
    Perrot-Minnot, Marie-Jeanne
    ;
    Rigaud, Thierry
    ;
    Anholt, Bradley R
    Hypothesis: Genetic variation for the primary sex ratio is widespread in a copepodwith polygenic sex determination. Cytoplasmic sex ratio distorters (e.g. Wolbachia andmicrosporidians) influence the primary sex ratio in this copepod.
    Organism: The intertidal copepod, Tigriopus californicus; six populations from VancouverIsland, British Columbia.
    Study site: Quantitative genetics experiment in the laboratory. PCR and antibioticsexperiment to test for the presence of cytoplasmic sex ratio distorters.
    Results: Genetic variation for the primary sex ratio was found in five of the six populationssurveyed. The primary sex ratio was paternally transmitted. There was no evidence thatWolbachia or microsporidians influenced the primary sex ratio of T. californicus.
  • Publication
    Accès libre
    Paternal inheritance of the primary sex ratio in a copepod
    (2005)
    Voordouw, Maarten 
    ;
    Robinson, H. Eve
    ;
    Anholt, Bradley R.
    Uniparentally inherited genetic elements are under strong selection to manipulate sex determination in their host and shift the host sex ratio towards the transmitting sex. For any sex-ratio trait, lineage analysis and quantitative genetics are important tools for characterizing the mode of inheritance (biparental vs. maternal vs. paternal) thereby narrowing the field of possible sex-determining mechanisms (e.g. polygenic, sex chromosomes with meiotic drive, cytoplasmic microorganisms). The primary sex ratio of the harpacticoid copepod, Tigriopus californicus is often male-biased and is highly variable among full sib families. We found that this extra-binomial variation for the primary sex ratio is paternally but not maternally transmitted in T. californicus. Paternal transmission of the primary sex ratio has been well documented in the haplo–diploid hymenoptera but is relatively rare in diplo–diploid organisms. If the sex-ratio trait is paternally transmitted in other closely related harpacticoid copepods it would explain why male biased primary sex ratios are so common in this group.
  • Publication
    Accès libre
    Heritability of Sex Tendency in a Harpacticoid Copepod, Tigriopus californicus
    (2002)
    Voordouw, Maarten 
    ;
    Anholt, Bradley R.
    Systems with genetic variation for the primary sex ratio are important for testing sex-ratio theory and for understanding how this variation is maintained. Evidence is presented for heritable variation of the primary sex ratio in the harpacticoid copepod Tigriopus californicus. Variation in the primary sex ratio among families cannot be accounted for by Mendelian segregation of sex chromosomes. The covariance in sex phenotype between full-sibling clutches and between mothers and offspring suggests that this variation has a polygenic basis. Averaged over four replicates, the full-sibling heritability of sex tendency is 0.13 ± 0.040; and the mother-offspring heritability of sex tendency is 0.31 ± 0.216. Genetic correlations in the sex phenotype across two temperature treatments indicate large genotype-by-temperature interactions. Future experiments need to distinguish between zygotic, parental, or cytoplasmic mechanisms of sex determination in T. californicus.
  • Publication
    Accès libre
    Environmental sex determination in a splash pool copepod
    (2002)
    Voordouw, Maarten 
    ;
    Anholt, Bradley R.
    The sex-determining mechanism has important demographic and genetic consequences by virtue of its effect on the population sex ratio. Here we investigate the effect of temperature dependent sex determination (TSD) on the primary sex ratio of the harpacticoid copepod, Tigriopus californicus. At the two experimental temperatures (15° and 22°C) used in this study, the primary sex ratio is almost always biased in favour of males. Higher temperatures induce masculinization and the change in sex ratio is not caused by differential mortality of the sexes. The mean level of TSD in the population is small (proportion of males increases by ~5% between 15° and 22°C) because only one-third of the families actually exhibit a significant sex-ratio response while the rest of the population is insensitive to temperature. A comparison of the primary sex ratio and the level of TSD between two locations reveals few differences among populations. Finally, individuals still exhibited TSD after having been maintained under constant temperature conditions in the lab for several generations. In addition the proportion of temperature-sensitive individuals remained unchanged. This suggests that the observed level of TSD is not an artefact of testing field-captured individuals in a novel laboratory environment. At this point the adaptive significance of temperature-dependent sex determination in T. californicus remains unknown.