What does selective pressure refer to in the context of genetics?

Selective pressure refers to an environmental factor that influences the survival and reproduction rates of organisms within a population, effectively selecting for certain traits that provide an advantage in that environment. This means that individuals with favorable traits are more likely to survive and reproduce, passing those advantageous traits onto the next generation.

For example, in a population of animals, if a particular color of fur provides better camouflage from predators, individuals with that color may survive longer and produce more offspring than those without it. Consequently, the frequency of the advantageous trait increases in the population over generations due to this selective pressure.

Other options fail to capture the essence of selective pressure. The first choice implies that the environmental factor has no impact on survival, which contradicts the definition of selective pressure. The third choice states that selective pressure decreases genetic variation; however, while it can lead to reduced variation in certain traits over time, it does not directly cause a decrease in overall genetic variation. The fourth choice suggests that selective pressure affects only certain species, but in reality, it can apply to any species within a particular environment, influencing a wide range of traits across different populations.