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User:Hu.ben/Cytoplasmic incompatibility

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Symptoms

Cell biology

Evolutionary implications

CI, as described by Werren [1], results in selection pressure on uninfected females, as infected females can mate both with uninfected males and infected males, but uninfected females cannot mate with infected males. As Wolbachia are only transmitted by females this mechanism promotes the spread of Wolbachia and therefore keeps Wolbachia from dying out because of incomplete transmission.


Population Genetics

The invasion of a population with CI-inducing Wolbachia bacteria can have different effects on the population's dynamics. At low prevalence of Wolbachia the probability for an uninfected female to lose progeny because of mating with an infected male is fairly low. This loss of uninfected individuals can be outweighed by the production of uninfected ones due to the incomplete transmission of Wolbachia. If the prevalence of CI-inducing Wolbachia is high enough, the probability for an uninfected female to mate with an infected male is high and it is thus preferable to the female's fitness to be infected. Therefore, there exists an invasion threshold for the spread of Wolbachia in an uninfected population, which depends on the transmission rate of the infection and the portion of incompatible progenies which survive until they can sexually reproduce. Below this threshold the invaders will die out, above this threshold the prevalence will reach a stable equilibrum. Typical thresholds in real populations are around 10% (See Fine[2] and Stouthamer et al. [3]).

As described by Stouthamer the invasion threshold may be reached in two ways[3].

  • In small populations a small number of infected individuals is sufficient to reach the invasion threshold
  • In bigger populations the division of the population into small subpopulations that only exchange a small number of individuals in each generation, can lead to an invasion of this subpopulation.

Speciation

It is speculated that CI can lead to "rapid speciation"[1] when there are two populations of one species that are infected by different Wolbachia strains. These two populations then might be bidirectionally incompatible, which might lead to speciation.

References

  1. ^ a b Werren, J (1997). "Biology of Wolbachia", Annual Review of Entomology 42: 587-609
  2. ^ Fine, P (1978). "On the Dynamics of Symbiote-Dependent Cytoplasmic Incompatibility in Culicine Mosquitoes", Journal of Invertebrate Biology 30:10-18.
  3. ^ a b Stouthamer, R (1999). "WOLBACHIA PIPIENTIS: Microbial Manipulator of Arthropod Reproduction", Annual Review of Microbiology 53: 71-102.

(1) http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6T9H-3VYTMKV-4&_user=964000&_rdoc=1&_fmt=&_orig=search&_sort=d&_docanchor=&view=c&_rerunOrigin=scholar.google&_acct=C000049508&_version=1&_urlVersion=0&_userid=964000&md5=b84e56c4da12ae4a89c306545f8e26f9

(2) http://jcs.biologists.org/cgi/content/abstract/119/17/3655

(3) http://www.sciencemag.org/cgi/content/abstract/296/5570/1124

(4) http://arjournals.annualreviews.org/doi/abs/10.1146%2Fannurev.ento.42.1.587

(5) http://www.nature.com/nrmicro/journal/v6/n10/abs/nrmicro1969.html

(6) http://arjournals.annualreviews.org/doi/abs/10.1146%2Fannurev.micro.53.1.71

(7) http://arjournals.annualreviews.org/doi/abs/10.1146/annurev.genet.41.110306.130354

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