Final answer:
Natural selection is a key mechanism of evolution, favoring individuals with beneficial mutations that increase survival and reproduction. While mutation causes random genetic variation, natural selection non-randomly increases the frequency of advantageous traits in the population over time.
Step-by-step explanation:
The process of evolution is driven by natural selection, a mechanism by which individuals with favorable traits have a higher probability of surviving and reproducing. This process begins with mutation, which introduces new genetic variation within a species. These mutations can be beneficial, neutral, or detrimental to an organism's survival. When environmental pressures act on the population, those individuals whose mutations result in traits that are advantageous for survival (adaption) tend to reproduce more successfully, passing these traits on to the next generation. Over time, the accumulation of beneficial traits can result in a population that is better suited to its environment.
Importantly, while mutation is random, natural selection itself is not random. The environment effectively 'selects' the most suitable traits through a non-random process. This means that not all mutations will be preserved through natural selection—only those that confer a survival or reproductive advantage in a given environment. Consequently, although mutations occur by chance, the overall trend of evolution is shaped by the non-random process of natural selection, leading to the preferential survival of beneficial traits.