Daily Newsletter March 16, 2012
Today's Topic: Bacterial Evolution
As we have discussed this week, bacterial evolution is slightly different from Eukaryotic evolution. Natural selection is the same; what changes is the inheritance patterns. Hardy-Weinberg equilibrium (equation)does not hold for haploid organisms, and we can not follow inheritance through Mendelian genetics.
So, how does it compare to Eukaryotic evolution? Can we use information from bacterial evolution to inform eukaryotic evolution? The answer is YES.
Bacteria are a simple system to use in labs. The genome is smaller than eukaryote, and they grow faster. This means faster replication. As you may remember, the greatest risk of mutation is in the replication event. Outside of replication, you mutate only due to chemical or extreme environmental conditions. Replication errors are the main source of mutation. So why is mutation important? It is the foundation for all variation (allelic variation within a gene).
First off, as the article demonstrates, we can use bacterial models to show us how a beneficial mutation arises, and how long it takes for such a mutation to occur. It takes a sequence of multiple mutations to make a beneficial variation, and most of the time the mutations just lead to neutral results. There is also the loss of individuals who had negative mutations. In therms of time frame, we are looking at 10's of thousands of generations. Can this be compared to mutation rates in eukaryotic cells? Yes. It helps us to understand how we get radical phenotypic variations among individuals of a population or species.
Second, we can use bacteria as models for genomic comparisons. Looking for similarities and differences in a genome is laborious, but can be done. Using a simple system, such as bacteria, allows researchers to test procedures and hypotheses, as well as building algorithms to run the mathematical comparisons. In other words, we can create research systems in bacteria that we could transfer to studying eukaryotic genomes.
Take some time and look around the internet. Look at bacterial evolutionary studies. What do you find? What interests you? Provide references for what you find interesting, and talk about it. Ultimately, your question is: How do studies in bacterial evolution inform our understanding of bacteria?
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