Evolution and Evolvability

Evolution does not operate with a goal in mind. Selecting for individuals with traits advantageous for a particular environment, organisms adapt to their habitat over time by means of natural selection changing the genetic frequencies of populations over time. Researchers at the university of Pennsylvania for the first time have found evidence that organisms that have a greater capacity for changing in environments far better in rapidly changing environments; natural selection has acted on evolvability. Dustin Brisson, an assistant professor in the school of arts and sciences departments stated that "what we were asking is whether the ability of an organism to evolve is a trait that natural selection can pick." Organisms such as "pathogens face a very strong selection pressure from the hosts immune system" and will die if they do not adapt.

Using this concept the Lyme disease bacteria, Borrelia burgdorferi, was focused on. This organism possesses the protein essential for establish long term infection, VIsE. Preceded by "cassettes", normally not expressed or made into proteins, these can recombine with VIsE to alter the expressed protein and challenge host immune defenses. Diversity in "cassettes" offer a window into past natural selection for a more evolvable VIsE giving organisms with greater diversity among them a selective advantage to evolve antigenically. Researchers evaluated 12 strains of B. burgdorferi for signs that natural selection had acted to increase the diversity of the cassettes and found evidence in favor of evolution for more diversity amount the cassettes. Together with genetically diverse cassettes, leading to more genetically diverse expression of the protein VIsE, results provide evidence that evolvability was the target of natural selection. With climate change and  mass extinction in mind knowledge of evolvability that can be studied can be an asset to population management.

http://www.sciencedaily.com/releases/2013/11/131114193434.htm

http://rsbl.royalsocietypublishing.org/content/5/1/44.full