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Evolution of sex allocation in protozoan pathogens

Reference	BB/C509915/1
Principal Investigator / Supervisor	Professor Andrew Read
Co-Investigators / Co-Supervisors	Professor Sarah Reece, Professor Stuart West
Institution	University of Edinburgh
Department	Inst for Immunology and Infection Resrch
Funding type	Research
Value (£)	183,094
Status	Completed
Type	Research Grant
Start date	10/10/2005
End date	09/10/2008
Duration	36 months

Abstract

The Phylum apicomplexa (Protozoa) includes some of the most serious pathogens of livestock and humans. These parasites must undergo a round of sexual reproduction to transmit to new hosts. Consequently, it is crucial that they produce the sex ratio that will maximise transmission to new hosts. Theory predicts that the sex ratio (proportion male) will be negatively correlated with the inbreeding rate. In addition, recent theory has shown that when transmission success is compromised, parasites should respond by increasing their investment in sexual stages or by producing a less female biased sex ratio than predicted by their inbreeding rate. However, data to support these predictions are weak and observed sex ratios are extremely diverse, making the application of sex allocation theory to protozoan parasites a contentious issue. Recent advances in malariology, not least new genomic information and new molecular techniques, now make it possible to exploit rodent plasmodia as experimental models for direct tests of the underlying assumptions and predictions of sex allocation theory as developed for protozoan parasites. Using a mouse-malaria experimental model, we will use clone-specific quantitative PCR, and gametocyte-specific quantitative reverse transcriptase PCR to investigate pathogen sex ratios at low densities and under immune onslaught, and to track the sex ratios of individual clones in mixed clone infections. These experiments will determine how protozoan parasites alter sex ratio in clinically and epidemiologically important ways and, for the first time, directly test whether variation in inbreeding probability (local mate competition) can explain variation in sex ratios within and between infections. Understanding how diversity is maintained in a trait like sex ratio, which is so closely linked to fitness, is a major issue in evolutionary biology.

Summary

unavailable

Committee	Closed Committee - Animal Sciences (AS)
Research Topics	Microbiology
Research Priority	X – Research Priority information not available
Research Initiative	X - not in an Initiative
Funding Scheme	X – not Funded via a specific Funding Scheme

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