CURRENT POST PostDoc CONTACT Gump Station, University of California Berkeley BP 244, 98728 Moorea, French Polynesia Phone: +689 56 52 87 / +689 26 90 18 Fax: +689 56 13 74 E-mail: s.charlat@ucl.ac.uk

BRIEF C.V.

2002-present: Post-doc at University College London / UC Berkeley, Moorea, French Polynesia
1998-2003: PhD at the University of Paris 6
1998-1999: D.E.A. at the University of Paris 11
1998: Research in Conservation biology, north-west Ecuador
1997-1998: Erasmus Student at the University of Leeds
1993-1997: DEUG, License, Maitrise in Cell Biology and Physiology at the University of Versailles & University of Paris 11

RESEARCH INTERESTS

Different replicating entities (different genes, different organisms, whatsoever...) often live together, and share common reproductive pathways. This is symbiosis. Relationships between the different actors are complex and dynamic: a never-ending game of conflict and cooperation.

I am focusing on one special case of symbiosis, where a bacterium (Wolbachia: the symbiont) inhabits the cells of larger organisms (Arthropods and Nematodes: the hosts). Wolbachia is well known for its dramatic effects on host reproduction: it can turn males to females, kill males, or cause complex patterns of sterility. In many cases, Wolbachia misdeeds appear to be good for females and bad for males, which makes sense from an evolutionary perspective, because only females transmit the bacterium across generations (through the egg cytoplasm). Males are dead ends.

The diversity of Wolbachia effects is amazing: it illustrates many of the possible evolutionary trajectories of symbiosis. I am personally working on the following issues:

1. The evolution of Wolbachia compatibility types. Cytoplasmic Incompatibility can occur in crosses between males and females bearing different Wolbachia strains. In other words, different Wolbachia strains can harbor different “compatibility types”. What evolutionary processes underlie this diversity? How fast do compatibility types diverge when isolated in different host species? I have been using a combination of theoretical and empirical approaches to address this issue.

2. The evolutionary consequences of sex-ratio distorters. The South Pacific butterfly Hypolimnas bolina is infected by a male-killing Wolbachia: infected females’ sons die before hatching. In this system, the prevalence of the male-killer varies from 0 to 99.9% between islands, resulting in drastic variation of sex-ratio in natural populations. Using a comparative approach (comparing different populations harboring different sex-ratio) I am trying to identify the ecological and evolutionary consequences of male-rareness on the butterfly reproductive biology.

REFERENCES

Main publications: 

Charlat, S., Engelstädter, J., Dyson, E.A., Hornett, E.A., Duplouy, A., Tortosa, P., Davies, N., Roderick, G.K. Wedell, N. & Hurst, G.D.D.
Competing selfish genetic elements in the butterfly Hypolimnas bolina.
Current Biology, in press.

Hornett, E.A., Charlat, S., Duplouy, A.M.R., Davies, N. Roderick, G.K., Wedell, N. & Hurst, G.D.D.  Evolution of Male Killer Suppression in a Natural Population.
PLoS Biology 4: e283.   [ pdf ]

Engelstädter, J., Charlat, S., Pomiankowski, A. & Hurst, G.D.D. 2006.
The evolution of cytoplasmic incompatibility types: Integrating segregation, inbreeding, and outbreeding.
Genetics 172: 2601-2611.

Engelstädter, J. & Charlat, S. 2006.
Outbreeding selects for spiteful cytoplasmic elements.
Proceedings of the Royal Society of London B, 273, 923-929.

Charlat, S., Hornett, E.A., Dyson, E.A., Ho, P.P.Y., Loc, N.T., Schilthuizen, M., Davies, N., Roderick, G.K. & Hurst, G.D.D. 2005.
Is extreme male-killer prevalence a local or common event in the butterfly Hypolimnas bolina? A survey across Indo-Pacific populations.
Mol. Ecol., 14, 3525-3530.   [ pdf ]

Charlat, S. Calmet, C. Andrieu, O. & Merçot, H. 2005.
Exploring the evolution of Wolbchia compatibility types: a simulation approach.
Genetics, 170, 495-507.   [ pdf ]

Charlat, S., Riegler, M., Baures, I., Poinsot, D., Stauffer, C. & Merçot, H. 2004.
Incipient evolution of Wolbachia compatibility types.
Evolution, 58:1901-1908.   [ pdf ]

Zabalou, S. Charlat, S. Nirgianaki, A. Lachaise, D. Merçot, H. & Bourtzis, K. 2004.
Natural Wolbachia infections in the Drosophila yakuba species complex do not induce cytoplasmic incompatibility but fully rescue the wRi modification.
Genetics, 167:827-834.   [ pdf ]

Charlat, S. Ballard, J.W.O. & Merçot, H. 2004.
What maintains noncytoplasmic incompatibility inducing Wolbachia in their hosts: a case study from a natural Drosophila yakuba population.
Journal of Evolutionary Biology, 17:322-330.   [ abstract ]   [ full text ]

Riegler, M. Charlat, S. Stauffer, C. & Merçot, H. 2004.
Wolbachia transfer from Rhagoletis cerasi to Drosophila simulans: investigating the outcomes of Host-symbiont coevolution.
Applied Environmental Microbiology, 70:273-279.   [ pdf ]

Charlat, S. Le Chat, L. & Merçot., H. 2003.
Characterization of non-Cytoplasmic Incompatibility inducing Wolbachia in two continental African populations of Drosophila simulans.
Heredity, 90: 49-55.   [ abstract ]   [ full text ]

Charlat, S. Bonnavion, P. & Merçot., H. 2003.
Wolbachia segregation dynamics and levels of Cytoplasmic Incompatibility in Drosophila sechellia.
Heredity, 90:157-61.   [ abstract ]   [ full text ]

Charlat, S., Nirgianaki, A., Bourtzis, K. & Merçot, H. 2002.
Evolution of Wolbachia-induced cytoplasmic incompatibility in Drosophila simulans and D. Sechellia.
Evolution, 56:1735-1742.   [ pdf ]

Charlat, S. Calmet, C. & Merçot, H. 2001.
On the mod resc model and the evolution of Wolbachia compatibility types.
Genetics, 159:1415-1422.    [ pdf ]

Charlat, S. Thatcher, O.R., Hartmann, N, Patel, Y., Saillan, M. & Vooren, E. 2000.
Survey of Alouatta palliata at the Bilsa biological reserve, north-west Ecuador.
Neotropical Primates, 8:40-44.   [ pdf ]

Reviews:

Merçot, H. & Charlat, S. 2004.
Wolbachia infections in Drosophila melanogaster and D. simulans: Polymorphism and levels of cytoplasmic incompatibility.
Genetica, 120: 51–59.   [ pdf ]

Charlat, S. Hurst, G.D.D. & Merçot, H. 2003.
Evolutionary consequences of Wolbachia infections.
Trends in Genetics, 19:217-23.    [ pdf ]

Poinsot, D. Charlat, S. & Merçot, H. 2003.
On the mechanism of Wolbachia-induced cytoplasmic incompatibility: confronting the models to the facts.
BioEssays, 25:259-265.   [ pdf ]

Charlat, S. & Merçot, H. 2000.
Wolbachia trends.
Trends in Ecology and Evolution, 15:438-440.   [ pdf ]

Book Chapters:

Charlat, S., Bourtzis, K. & Merçot, H. 2001.
Wolbachia-induced cytoplasmic incompatibility.
In Symbiosis (Seckbach, J. ed). Kluwer Academic Publisher, Dordrecht, pp 621-644.   [ pdf ]

Veneti, Z., Reuter, M. , Montenegro, H.,  Hornett, E. A.,  Charlat, S. and Hurst, G.D.D. 2005.
Interactions between inherited bacteria and their hosts: The Wolbachia paradigm.
Pp. 119-142 In McFall Ngai, M., Ruby, E.G. & Henderson, B. (eds.) The influence of bacterial communities on host biology. C.U.P..

Short notes and Comments:

Charlat, S. & Merçot, H. 2002.
True parthenogenesis induction or successful feminization?
Trends in Genetics, 18:70-71.   [ pdf ]

Charlat, S. & Merçot, H. 2001.
Wolbachia and recombination.
Trends in Genetics, 17:493.   [ pdf ]

Charlat, S. & Merçot, H. 2001.
Cytoplasmic incompatibility and maternal-haploid.
Trends in Genetics, 17:440-441.   [ pdf ]

Charlat, S. & Merçot, H. 2001.
Did Wolbachia cross the border?
Trends in Ecology and Evolution, 16:540-541.   [ pdf ]

Charlat, S. & Merçot, H. 2001.
Wolbachia, mitochondria and sterility.
Trends in Ecology and Evolution, 16: 431-432.   [ pdf ]