Abstracts (first author)

Talk 

Deadly antibiotics and evolutionary rescue via horizontal gene transfer

Author(s): Jalasvuori M, Ojala V, Mattila S

Summary:

Evolution has caused one of the most concrete problems in the modern world by selecting for drug resistant bacteria. When bacteria are exposed to lethal levels of antibiotics, it has been assumed that there needs to be a pre-existing mutation for resistance within the population in order for the bacterial strain to survive the drug treatment. However and given that majority of resistance genes are carried by mobile genetic elements such as conjugative plasmids that can move between bacterial cells, it is possible that the resistance gene pre-exist in another bacterium which then rescues susceptible bacteria via horizontal gene transfer. We investigated whether bacteria may survive lethal antibiotic selection by acquiring resistance genes horizontally, and, if so, could this process be somehow prevented. Indeed and contradictory to previous paradigm, we demonstrate that the resistance does not need to pre-exist within the population as some bacteriosidic antibiotics cannot kill susceptible bacteria when the surrounding bacterial community carries mobile elements with resistance genes. Moreover, we show that viruses specifically infecting bacteria with mobile elements can both prevent the spread of resistances to other bacteria and to lead to the loss of resistance conferring elements from the population. Altogether these results suggest that the composition of bacterial community along with their viruses can play a defining role in the evolution antibiotic resistances.



Abstracts (coauthor)

Summary:

Dispersal is a fundamental characteristic of organisms -- it determines the spatial, genetic, and demographic structure of population and is necessary for the persistence of any species. However, from the perspective of the individual, dispersal often carries substantial costs that can come in the currencies of energetics, time, risk and opportunities. Often the dispersal strategy favored by individuals will not be the strategy that would be ‘best’ for the population (best in terms of maximizing size or distribution). This leads to one of two results 1) individuals disperse less than is best for the population (“inertia”) or 2) individuals disperse more than is best for the population (“hypermobility”). Models of dispersal are often constructed to avoid edge effects, however, the real world is full of edges. A major risk of dispersal, the possibility of landing in unfavorable habitat, becomes exacerbated in habitats that are not only potentially fragmented but also have sharp boundaries (e.g., an archipelago). One might therefore predict inertia to be a problem in worlds of small size where most habitat is near an edge. Here we construct a model to address these questions. We find that small worlds, small patch carrying capacities, and high dispersal mortality all lead to inertia whereas large worlds, large patch carrying capacities, and low dispersal mortality lead to hypermobility. We also show that although heterogeneity in individual dispersal behavior can increase long-distance dispersal events, this is not guaranteed to be so. In a subset of parameter space heterogeneity actually decreases the probability of long-distance dispersal, in contrast to previous thinking.

Contacts

Chairman: Octávio S. Paulo
Tel: 00 351 217500614 direct
Tel: 00 351 217500000 ext22359
Fax: 00 351 217500028
email: mail@eseb2013.com

Address

XIV Congress of the European Society for Evolutionary Biology

Organization Team
Department of Animal Biology (DBA)
Faculty of Sciences of the University of Lisbon
P-1749-016 Lisbon
Portugal

Website

Computational Biology & Population Genomics Group 
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