1. Natural Selection: Natural selection operates through the process of variation, inheritance, and differential survival. Individuals within a species show variation in their traits due to genetic diversity. Some of these variations may provide an advantage or disadvantage in the environment in which the species lives. In the process of natural selection, individuals with advantageous traits have a better chance of surviving and reproducing, passing on those traits to their offspring. Over time, this leads to the gradual accumulation of favorable traits within the species, making them better adapted to their environment and more likely to survive. Conversely, individuals with less favorable traits are less likely to survive and reproduce, leading to the gradual elimination of those traits from the population.
2. Adaptation: Successful adaptation is crucial for survival and reproduction. Species that can adapt to changing environmental conditions, such as changes in climate, availability of resources, or presence of predators, are more likely to survive. Adaptations can take various forms, including physiological, behavioral, or morphological changes. For instance, a species may develop thicker fur to survive cold temperatures, learn to migrate to more favorable areas, or evolve new defensive mechanisms against predators.
These factors are key components of Darwin's theory of evolution by natural selection. Survival of the fittest, as popularized by Herbert Spencer, is a simplification of Darwin's concepts. Darwin proposed a more nuanced and complex process where both natural selection and adaptation determine which species persist over time.