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Cytoplasmic incompatibility in Drosophila populations: influence of assortative mating on symbiont distribution

S L O'Neill1

  • 1Department of Entomology, University of Queensland, St. Lucia, Australia.

Journal of Invertebrate Pathology
|November 1, 1991
PubMed

Insights

Cytoplasmic incompatibility in Drosophila, linked to endosymbiont infections, is rare and scattered, contradicting spread models. Mating preferences do not explain observed infection patterns in D. simulans.

Area of Science:

  • Evolutionary Biology
  • Microbial Ecology
  • Genetics

Background:

  • Cytoplasmic incompatibility (CI) is a reproductive isolation mechanism observed in Drosophila species.
  • CI is often mediated by endosymbiotic microorganisms within the host cytoplasm.
  • Previous models predicted rapid spread of CI-inducing infections in host populations.

Purpose of the Study:

  • To survey the distribution of endosymbiont infections causing CI in Drosophila simulans and Drosophila melanogaster.
  • To investigate the population genetics and mating behavior associated with CI in natural populations.
  • To reconcile observed infection patterns with theoretical models of symbiont spread.

Main Methods:

  • Field surveys of Drosophila populations across diverse geographical locations.
  • Microscopic examination and/or molecular techniques to detect endosymbiont infections.
  • Analysis of isofemale lines to assess mating preferences between infected and uninfected individuals.

Main Results:

  • Infected populations of D. simulans and D. melanogaster were found to be rare and patchily distributed.
  • The observed distribution contradicts models predicting rapid and widespread dissemination of CI-inducing infections.
  • No consistent assortative mating preferences were detected between infected and uninfected D. simulans in polymorphic populations.

Conclusions:

  • The prevalence and distribution of endosymbiont infections in Drosophila are more complex than predicted by simple deterministic models.
  • Factors beyond basic incompatibility, such as host-symbiont interactions and population structure, likely influence infection dynamics.
  • Further research is needed to understand the ecological and genetic factors maintaining polymorphism in natural populations.

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