Why is mutation a random process but natural selection not?

Answer 1

genetic drift is a change in evolution based on small mutations in genetic make up over generations

natural selection is survival of the fittest, where only the surviving species will reproduce and live on

natural selection is caused partly due to genetic drift, since the mutated species will adapt to their surroundings and therefore become the fittest species.

Answer 2

Yes, mutation is natural and continual. In Biology, mutation usually refers to changes to the DNA within a cell. Some mutations may occur due to radiation or chemicals. For example, in your skin cells, some frequencies of UV light can directly damage DNA and other frequencies can cause chemical changes in the cell producing free radicals that, in turn, damage the DNA.

But the primary cause of mutation comes from a fundamental process of all life -- replication. Most cells replicate through mitosis, a process in which one cell basically makes clone of itself, and while errors are rare and the cell is able to repair many, given the size of the human genome (6 billion base pairs in body (somatic) cells) approximately 7 simple point mutations appear in each replication. Somatic cells undergo a much more complex replication (meiosis) in order to form eggs and sperm, and this process produced around 70-100 mutations per cell.

Should you be worried? Probably not. Mutations within somatic cells could cause cell death, aging or cancer, but these are small and manageable risks. But what about heredity? By comparing human and chimpanzee DNA, we know the only about 1 in 30-60 thousand mutations that occur in sperm or egg cells are beneficial enough to be preserved in the collective human gene pool. They rest are strongly selected against and do not survive for many generations. But mutations made us what we are.

Every human carries a mutation that breaks a gene critical to building muscle in the jaw. This gene is totally non-functional (it actually has missing molecules that render it worthless), and when it was first discovered, it was thought to signal a previously unrecognized form of muscle disease. But in fact, it reduced the size of our jaw muscle by a factor of 8. Without it, our jaw muscles would squeeze the skull forcing the skull bones to fuse in only 2 or three years, and limiting the maximum size of our brain to that of a chimp or toddler. So mutations are the allies of evolution.

Answer 3

Random means " in no set numerical order " and with mutation and drift you know it can happen, just not exactly when. With natural selection you know that if the certain conditions are met then adaptive change will happen. All selection needs is a differential reproductive success against the immediate environment for organisms that vary in traits which give some an advantage over others. So, population alleles change and evolution happens, even if speciation does not.

Answer 4

Mutation is (more or less; there are examples in which mutation is less random, but still quite random) random because it is a result of the chaotic interaction of molecules at the genetic level.

Natural selection, however, is - once a certain set of variants exist - predictable, to a certain degree: it is determined by the properties of those variants and the way they interact with their environment.

Answer 5

The natural selection ''select'' the advantageous mutations.