Molecular evolution is in part a process of evolution at the scale of DNA, RNA, and proteins. Molecular evolution emerged as a scientific field in the 1960s as researchers from molecular biology, evolutionary biology and population genetics sought to understand recent discoveries on the structure and function of nucleic acids and protein. Some of the key topics that spurred development of the field have been the evolution of enzyme function, the use of nucleic acid divergence as a "molecular clock" to study species divergence, and the origin of noncoding DNA. Recent advances in genomics, including whole-genome sequencing, high-throughput protein characterization, and bioinformatics have led to a dramatic increase in studies on the topic. In the 2000s, some of the active topics have been the role of gene duplication in the emergence of novel gene function, the extent of adaptive molecular evolution versus neutral processes of mutation and drift, and the identification of molecular changes responsible for various human characteristics especially those pertaining to infection, disease, and cognition.
In order for evolution to occur, three different processes are required and must be met:
- 1. Generation of a diverse population
- 2. Selection of members based on criterion of fitness
- 3. Reproduction to enrich the population in more-fit members
Nucleic acids are such molecules that are capable of undergoing all three processes. Combinatorial chemistry is the concept of rapidly producing an abundant amount of a specific molecule of interest. Because of this process, diverse populations of nucleic acid molecules can be synthesized. A common example of this process involves attempting to create an RNA molecule that specifically binds ATP and other nucleotides. First, a randomized pool of RNA sequences, called apimers, are placed into an ATP affinity column. Some RNA molecules are then found bounded to ATP. These molcules are released from the affinity column by adding excess ATP. This collection of molecules are allowed to replicate into DNA by using the enzyme reverse transcriptase. Once transcribed into DNA, the molecules undergo PCR, and ultimately transcribe back into RNA.