The Big Questions by Francisco Ayala

Author:Francisco Ayala [Ayala, Francisco J.]
Language: eng
Format: epub
Publisher: Quercus
Published: 2013-07-26T16:00:00+00:00

Genes and proteins

The discipline of molecular biology came into existence in the second half of the twentieth century. Molecular biology has become the most effective way of reconstructing evolutionary phylogeny because, as pointed out in What is Molecular Evolution?, it has three advantages over the traditional methods of classification based on fossils or comparative morphology: precision, because the information is readily quantifiable; universality, because all sorts of organisms, no matter how evolutionarily distant, can be compared; and multiplicity, because organisms have thousands of genes and proteins, every one of which reflects the same evolutionary history; more and more genes and proteins can be investigated in order to achieve the desired degree of resolution in the tree.

The Universal Tree of Life represented in the figure below can only be reconstructed with the methods of molecular biology. The tree in the figure was obtained with the genes that encode ribosomal RNA molecules, because they are among the slowest evolving genes, meaning that different degrees of similarity can be detected even among the most diverse organisms, such as bacteria compared to archaea and to eukaryotes.

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