The diversity and the unity of life are equally meaningful and striking aspects of our Earth (Dobzhansky, 1973). Although an astounding 1.2 million species have already been identified, it is estimated that another 8.7 million are yet, to be discovered and classified (Mora et al., 2011). By understanding what unifies us –our genes, our understanding of the organisms we share our planet with will continue to grow.
Genomic sequencing is the process of determining the precise order of nucleotides within a DNA molecule. It includes any method or technology that is used to determine the order of the four DNA bases – thiamine, adenine, guanine, and cytosine– in the strand of DNA (NHGRI, 2011). In each organism, these bases are arranged in a unique and specific sequence, and it is this sequence that is the genetic code of the organism. Genomic sequencing has had an impact on nearly every field of biological research including human genetics and genomics, plants and agriculture, microbes, medicine, viruses and infectious diseases, environmental genetics and evolutionary biology. By first examining the development of gene sequencing technology we will be able to view its role in evolutionary biology, its contribution to phylogenetics, and how it has changed our understanding of the biological tree of life.
Development of gene sequencing technology
The majority of scientific work in genetics and genomic sequencing has been done in the last 155 years. In 1859, Charles Darwin published On the Origin of Species where he proposed evolution by natural selection. Evolution is the change of inherited characteristics of biological populations over successive generations.Yet, the principals of genetics required to explain how characters are inherited were not known at the time. In 1865, Mendel’s work supplied the principals of heredity and introduced the concepts of dominant and recessive genes. It was this work, which eventually provided the missing link for understanding Darwin’s concept of evolution (Lorentz et al., 2002).
Upon reading Mendel’s work in 1900, William Bateson became a vocal supporter of Darwin’s theory of natural selection and believed that they provided a “genetic” explanation of the theory of evolution. He became the first person to use the term ‘genetics’ to describe the study of heredity. In 1953, Watson and Crick established that the structure of the DNA molecule was a double helix. Subsequently, Crick introduced a central premise of genetics – that DNA makes RNA makes proteins. The work of this time brought a new age of discovery in biology and laid the foundation for genome sequencing (Lorentz et al., 2002).
The first methods for sequencing DNA were developed in the 1970’s and the first full DNA genome – that of a bacteriophage was sequenced. In 1977, Fred Sanger and Alan Coulson developed a technique for rapid sequencing of long sections of DNA, and this would go on to transform biology as a whole by providing a...