Define and explain the following terms: Variation and Survival of the Fittest.

(N/A) $1$. Variation: Variation refers to the differences in characteristics or traits among individuals of the same species. These variations can be morphological,physiological,or behavioral. They arise due to genetic recombination during sexual reproduction,mutations,and environmental factors. Variations are the raw material for evolution as they provide the basis for natural selection.
$2$. Survival of the Fittest: This is a core concept of Darwinian natural selection. It states that individuals who are better adapted to their environment are more likely to survive and reproduce. 'Fitness' in this context refers to reproductive success,not just physical strength. Those who survive pass on their advantageous traits to the next generation,leading to evolutionary change over time.