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Beyond Darwin: Ways to Evolve New Functions (Sidebar)

EXPERTS IN SEVERAL DIVERSE FIELDS – including physics, biochemistry, genetics, evolutionary developmental biology, and mathematical biology – gathered at the latest Kavli Futures Symposium to understand how new functions, such as nerve signaling or the ability to elude the immune system, evolve in organisms. Understanding this process isn’t just academically interesting; one day researchers may be able to use the information they’ve gleaned about how evolution works to develop new vaccines or other biotechnology products. Here’s a brief wrap-up of the types of questions these researchers are trying to answer, and what they’ve learned so far.

How does novelty evolve?

How does a species develop traits that didn’t exist before? Experiments and modeling are revealing that, while evolution follows a limited number of pathways—the pathways of least resistance— there are many different mutational pathways that can be taken to create the same new trait or function, or to create new traits or functions yet to be seen in nature.

How did complex organs such as the nervous system evolve?

Researchers are seeking answers to this question by comparing the gene activity patterns of primitive animals to that of the first animals to develop nerves. From these investigations, researchers are uncovering that the nervous system evolves and becomes more complex by using the same genes found in lower organisms, but duplicating them or regulating their activity differently, so they can be put to new uses.

Primitive sponges, for example, have many of the basic building blocks needed to form the signal-transmitting synapses between nerve cells, but don’t put these proteins to use in this way. Instead the same proteins are used for other functions. Researchers have identified a core genetic network that regulates the development of the nervous system, and are exploring how exactly that regulation sculpts some tissues into nerves or brains. Investigations into how cell types change as one moves up the evolutionary tree of life is also helping uncover how complexity evolves.

What fosters evolution of new functions?

Researchers are trying to find the answer to this question in a variety of ways, with many efforts focused on proteins, which are the workhorses of the cell. Studies are revealing that evolution is fostered by certain proteins, called heat shock proteins, which become active when animals are exposed to higher than normal temperatures. Heat shock proteins help the animal continue to function at that higher temperature by preventing the breakdown of proteins misformed due to the excessive heat. This results in more variation in proteins occurring that could eventually lead to new traits. In addition, some mutations make certain proteins more stable so they can be further modified by new mutations. This is what enables the flu virus to be resistant to flu vaccines. Researchers hope to put these findings to use in their protein engineering and directed evolution efforts.

How do you get an enzyme to evolve?

Enzymes acts as a catalyst to cause a specific biochemical reaction in a living organism. Researchers are trying to determine how they evolve by using new lab-on-a-chip technologies, which enable investigators to screen billions of enzyme variants in just a few hours at a cost of only a few dollars, and are expected to be of enormous benefit for directed evolution. When investigators used this technology to repetitively screen and select particularly active enzymes in yeast after the genes that generate the enzymes had been mutated, they substantially boosted the activity rates of these enzymes.