Environmental genomics
Comparing the genomes of species which are relatively close but who live in different places will help understanding how an organism’s genome interacts with its environment.
Thanks to the great diversity of marine habitats and ecosystems, an extremely rich and varied fauna and flora is present in the ocean. In order to find out about all the species present in different environments such as the hydrothermal, upwelling zones, metagenomics (http://www.bioteach.ubc.ca/Biodiversity/Metagenomics/) has been invented allowing direct sequencing of the species present in seawater by the “shotgun” method. Metagenomics is the biology of mixed genomes or populations of organisms and enable having a representation of the different species that are present in seawater.
This technique allows overcoming the problems researchers had in raising some species. In fact, this method is direct and doesn’t require knowing which the optimal conditions of growth for each organism are.
Environmental Genomics can also help defining, confirming or invalidating the position of species in the evolutionary tree of life. In fact, sometimes very different species look so much alike that scientists used to believe they were closely related. The comparison of their genome allows revealing these unsuspected differences.
A species which looks very much alike the other ones of the group it has been put into but who in fact is very different genetically is called a cryptic species.
The technique which allows this genetic characterisation of species is called “barcoding” which is based on the presence of molecular markers which are conserved in species belonging to the same group.
Environmental genomics can change the way we think about adaptation and the way ecosystems evolve.
In fact, the capacity of organisms to get adapted to the changes in their environment depends on the plasticity of their genome. For example, a mutation in a gene can provoke the production of a protein that confers more resistance to pollutants. The mutation will be maintained if the individual is living in a polluted environment and will be transferred to more individuals of its population by reproduction. Comparing the genomes of closely related species living under different conditions, one under stress provoked by pollution and the other in a clean environment will allow finding out which kinds of mutations have appeared that enable the stressed species to survive.
This can help to understand how these species can be better adapted to their environment and help predict what will become of them with the global changes that are expected and already starting to be observed today.
Contributed by Stephanie Ries
