What principle does natural selection primarily describe?

Natural selection primarily describes the concept of "survival of the fittest" in the context of evolution. This principle, introduced by Charles Darwin, explains how individuals within a population that possess advantageous traits are more likely to survive and reproduce than those with less favorable traits. Over time, these beneficial traits become more common in the population, leading to evolutionary changes.

The process is driven by environmental pressures that determine which traits are favorable, thereby influencing reproductive success. As a result, natural selection not only shapes the characteristics of populations but also drives the evolution of species over generations. This principle is a cornerstone of evolutionary biology and helps explain the diversity of life and how organisms adapt to their environments.

While genetic mutations contribute to variation in traits, and the formation of new species can result from the cumulative effects of natural selection, these concepts are not the primary focus of natural selection itself. Similarly, the growth of populations in ecosystems relates more to population dynamics and resource availability than to the mechanism by which traits are selected for or against in evolutionary contexts.