Population Genetics

Research Interests

Evolutionary biology, theoretical ecology, population genetics, bacterial evolution, evolution of resistance to antibiotics, plasmid evolution.

Please visit our website here

Group Members

Ana Rita Ponce	Postdoc
	Tel: 21 446 4640
Rui Silva	External Masters Student
	Tel: 21 440 7900

Research Project

Evolution of Bacteria: the role of the interactions with neighboring bacterial communities and plasmids.

Bacterial evolution, including the evolution of traits such as antibiotic resistance and virulence, while being caused by the evolution of certain genes, it can also be influenced by interactions with the rest of the bacterial community. Here, "bacterial community" means other bacteria of the same or of different species, as well as their plasmids, transposons and other accessory elements typically found in bacteria. With this project, we are focusing in antibiotic resistance and in the following questions: why are plasmids present in so many bacterial communities?; How can plasmids adapt to bacteria (and vice-versa)? Given the intensity of antibiotic usage around the world, how can we still find antibiotic-susceptible bacteria?

Funding

SFRH/BPD/14820/2003
Evolution of Bacteria: the role of the interactions with neighboring bacterial communities and plasmids

Research Project

Population genetics of adaptation in Escherichia coli

All natural populations have to adapt to new environments. Knowledge of the genetics of adaptation should provide the centerpiece of a unified theory of evolution. Despite its extreme importance, the process of adaptation is far from being understood. For example: What is the rate at which positive Darwinian selection occurs in a natural population? What is the distribution of fitness effects throughout the adaptive process? Does adaptation involve the fixation of mutations with small or large effects? are some of the questions that we try to adress in this project.

Funding

POCTI/BSE/46856/2002
Population genetics of adaptation in Escherichia coli

Collaborators

Instituto Gulbenkian de Ciência, Oeiras, Portugal
We are collaborating with Dr. Isabel Gordo and Dr. Lisete Fernandes

University of Cornell, Ithaca, NY
We are collaborating with Dr Doris Bachtrog

Research Project

Mutator Dynamics in Escherichia coli

The proportion of mutators observed in surveys of natural populations is some orders of magnitude higher than expected under a simple mutation/selection equilibrium model. For example, certain viruses, bacteria and cancer cells have abnormal high mutation rates. This mutator phenotype is a two-edged sword: it confers the potential for faster adaptation but also the short time cost of deleterious mutations. However, understanding how mutators can rise in frequency is still an unsolved problem. The aim of this project is to contribute for the understanding of this.

Collaborators

Institute Necker - INSERM - Paris, France
Ivan Matic

Publications

Dionisio, F., Gordo, I. (2007). Controlling excludability in the evolution of cooperation Evolutionary Ecology Research (in press)

Combadão,J., Campos, P.R.A., Dionisio, F and Gordo, I. S. (2007). Small-World networks decrease the speed of Muller's ratchet Genetical Research (in press)

Dionisio, F., Gordo, I. (2006). The Tragedy of the Commons, the Public Goods Dilemma, and the meaning of Rivalry and Excludability in Evolutionary Biology. Evolutionary Ecology Research 8 :321-332

Campos, P.R.A., Combadão, J., Dionisio, F. and Gordo, I. (2006). Muller’s ratchet in random graphs and scale-free networks. Physical Review E 74 :042901

Gordo, I. & Dionisio, F. (2005). A non-equilibrium model for estimating the parameters of deleterious mutations. Physical Review of E 71,03190 Also published in the Virtual Journal of Biological Physics Research 9 (7)

Dionisio, F. (2005). Plasmids survive despite their cost and male-specific-phages due to heterogeneity of bacterial populations Evolutionary Ecology Research 7 :1089-1107

Dionisio, F., Conceição, I.C., Marques A.C.R., Fernandes, L. and Gordo, I. (2005). The evolution of a conjugative plasmid and its ability to increase bacterial fitness Biol. Lett. 1 :250-252

Dionisio, F., Matic, I., Radman, M., Rodrigues, O. R., Taddei, F. (2002). Plasmids spread faste in heterogeneous bacterial communities. Genetics 162(4) :1525-1532

Vulic, M., Dionisio, F. et al. (1997). Molecular Keys to Speciation: DNA Polymorphism and the Control of Genetic Exchange in Enterobacteria. Proc Natl Acad Sci 94 :9763-9767