Key Concepts of Natural Selection

Study Notes

Key Concepts of Natural Selection

Natural selection is the process where organisms better adapted to their environment tend to survive and produce more offspring. This leads to changes in the genetic makeup of a population over time.
Variation exists within populations. Individuals within a species exhibit variations in traits. These variations can be physical, behavioral, or physiological.
Inheritance of traits. Variations are often heritable, meaning they can be passed down from parents to offspring.
Overproduction of offspring. Organisms typically produce more offspring than can possibly survive. This leads to competition for limited resources.
Differential survival and reproduction. Individuals with traits better suited to their environment are more likely to survive and reproduce, passing those advantageous traits to their offspring.

Driving Forces of Natural Selection

Environmental pressures. The environment plays a crucial role in shaping the traits that are advantageous. Features like climate, food availability, and predators influence which traits are favoured.
Competition for resources. Scarcity of resources like food, water, or mates forces individuals to compete for survival. Individuals with traits that allow them to compete more effectively are more likely to survive.
Predation. Predators select against individuals that are vulnerable and less agile. Over time, populations evolve traits that make them better at avoiding predators.

Mechanisms of Natural Selection

Mutations. Random changes in DNA sequences can create new variations within a population. These mutations can be beneficial, neutral, or detrimental, influencing how well an organism is adapted to its environment.
Sexual selection. Individuals with traits that make them more attractive to mates are more likely to reproduce. This can drive the evolution of traits that seem less useful for survival, but are preferred by the opposite sex.
Genetic drift. Random fluctuations in the frequencies of alleles (different versions of a gene) can occur within a population, especially in small populations. These fluctuations can lead to changes unrelated to natural selection's influence on fitness.

Patterns of Natural Selection

Stabilizing selection: This type of selection favors the average phenotype, which can result in reduced variation within a population.
Directional selection: Favors one extreme phenotype over the others. The population shifts its average phenotype over time.
Disruptive selection: This type of selection favors both extreme phenotypes and reduces the frequency of the intermediate phenotype.

Description

Explore the fundamental principles of natural selection and how they shape the evolution of species. This quiz covers variation, inheritance, overproduction, and differential survival in populations. Test your understanding of these key concepts that drive the process of evolution.