Molecular Evolution - The Driving Forces of Evolution

The Driving Forces of Evolution

Depending on the relative importance assigned to the various forces of evolution, three perspectives provide evolutionary explanations for molecular evolution.

While recognizing the importance of random drift for silent mutations, selectionists hypotheses argue that balancing and positive selection are the driving forces of molecular evolution. Those hypotheses are often based on the broader view called panselectionism, the idea that selection is the only force strong enough to explain evolution, relaying random drift and mutations to minor roles.

Neutralists hypotheses emphasize the importance of mutation, purifying selection and random genetic drift. The introduction of the neutral theory by Kimura, quickly followed by King and Jukes' own findings, led to a fierce debate about the relevance of neodarwinism at the molecular level. The Neutral theory of molecular evolution states that most mutations are deleterious and quickly removed by natural selection, but of the remaining ones, the vast majority are neutral with respect to fitness while the amount of advantageous mutations is vanishingly small. The fate of neutral mutations are governed by genetic drift, and contribute to both nucleotide polymorphism and fixed differences between species.

Mutationists hypotheses emphasize random drift and biases in mutation patterns. Sueoka was the first to propose a modern mutationist view. He proposed that the variation in GC content was not the result of positive selection, but a consequence of the GC mutational pressure.

Read more about this topic:  Molecular Evolution

Famous quotes containing the words driving, forces and/or evolution:

    As it grew darker, I was startled by the honking of geese flying low over the woods, like weary travellers getting in late from Southern lakes, and indulging at last in unrestrained complaint and mutual consolation. Standing at my door, I could hear the rush of their wings; when, driving toward my house, they suddenly spied my light, and with hushed clamor wheeled and settled in the pond. So I came in, and shut the door, and passed my first spring night in the woods.
    Henry David Thoreau (1817–1862)

    The popularity of disaster movies ... expresses a collective perception of a world threatened by irresistible and unforeseen forces which nevertheless are thwarted at the last moment. Their thinly veiled symbolic meaning might be translated thus: We are innocent of wrongdoing. We are attacked by unforeseeable forces come to harm us. We are, thus, innocent even of negligence. Though those forces are insuperable, chance will come to our aid and we shall emerge victorious.
    David Mamet (b. 1947)

    What we think of as our sensitivity is only the higher evolution of terror in a poor dumb beast. We suffer for nothing. Our own death wish is our only real tragedy.
    Mario Puzo (b. 1920)