title: Sterile males in a parasitoid wasp with complementary sex determination: from fitness costs to population extinction.
abstract: BACKGROUND
  Single-locus complementary sex determination (sl-CSD), which occurs in some insects of the order Hymenoptera, imposes a heavy genetic load that can drive small populations to extinction. The core process in these species is the development of individuals homozygous at the sex-determining locus into unfit diploid males. The risk of extinction of populations with sl-CSD is theoretically much higher if diploid males are viable and capable of mating but sterile, because diploid males then decrease the reproductive output of both their parents and the females with which they mate.
  
  
  RESULTS
  In the parasitoid wasp Venturia canescens (Hymenoptera: Ichneumonidae), diploid males resembled their haploid counterparts in most respects, but their mating success was nevertheless lower than that of haploid males, especially when the two types of males were placed in competition. Furthermore, although diploid males transferred viable sperm during copulation, they sired no daughters: the females with which they mated produced only sons, like virgin females. A simulation model combining behavior, genetics and demography demonstrated that for two alternative hypotheses concerning the fertilization success of diploid sperm, the mating success of diploid males strongly affected population dynamics.
  
  
  CONCLUSIONS
  The performance of diploid males should be estimated in competitive situations. It is a crucial determinant of the probability of extinction.
authors.affiliation: INRA, UMR 1355 Institut Sophia Agrobiotech, 06903, Sophia Antipolis, France. xavier.fauvergue@sophia.inra.fr.|Université de Nice Sophia Antipolis, UMR Institut Sophia Agrobiotech, 06903, Sophia Antipolis, France. xavier.fauvergue@sophia.inra.fr.|CNRS, UMR 7254 Institut Sophia Agrobiotech, 06903, Sophia Antipolis, France. xavier.fauvergue@sophia.inra.fr.|Institut Sophia Agrobiotech, 400 Route des Chappes, BP 167, 06903, Sophia-Antipolis Cedex, France. xavier.fauvergue@sophia.inra.fr.
authors.forename: Xavier
authors.initials: X
authors.lastname: Fauvergue
authors.affiliation: Université de Lyon, Lyon F-69000, France; Laboratoire de Biométrie et Biologie Evolutive, Universite Lyon 1, CNRS, UMR 5558, F-69622, Villeurbanne, France. chuine.anna@gmail.com.
authors.forename: Anna
authors.initials: A
authors.lastname: Chuine
authors.affiliation: INRA, UMR 1355 Institut Sophia Agrobiotech, 06903, Sophia Antipolis, France. chloevayssade@gmail.com.|Université de Nice Sophia Antipolis, UMR Institut Sophia Agrobiotech, 06903, Sophia Antipolis, France. chloevayssade@gmail.com.|CNRS, UMR 7254 Institut Sophia Agrobiotech, 06903, Sophia Antipolis, France. chloevayssade@gmail.com.
authors.forename: Chloé
authors.initials: C
authors.lastname: Vayssade
authors.affiliation: INRA, UMR 1355 Institut Sophia Agrobiotech, 06903, Sophia Antipolis, France. alexandra.auguste@sophia.inra.fr.|Université de Nice Sophia Antipolis, UMR Institut Sophia Agrobiotech, 06903, Sophia Antipolis, France. alexandra.auguste@sophia.inra.fr.|CNRS, UMR 7254 Institut Sophia Agrobiotech, 06903, Sophia Antipolis, France. alexandra.auguste@sophia.inra.fr.
authors.forename: Alexandra
authors.initials: A
authors.lastname: Auguste
authors.affiliation: Université de Lyon, Lyon F-69000, France; Laboratoire de Biométrie et Biologie Evolutive, Universite Lyon 1, CNRS, UMR 5558, F-69622, Villeurbanne, France. emmanuel.desouhant@univ.lyon1.fr.
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Desouhant
mesh_terms: D000818:Animals; D004171:Diploidy; D005260:Female; D056084:Genetic Fitness; D006238:Haploidy; D007248:Infertility, Male; D008297:Male; D011157:Population Dynamics; D012098:Reproduction / Q000235:genetics; D019849:Sex Determination Processes / Q000235:genetics*; D012726:Sexual Behavior, Animal; D014863:Wasps / Q000235:genetics / Q000502:physiology*