Natural and Artificial Selection Lecture Review

Natural Selection is the process where population characteristics change over generations as individuals with specific inherited traits survive local environmental conditions and pass alleles to offspring.
A population is defined as a group of organisms of the same species living in the same area at the same time.
Example: The Grey Tit birds near Chernobyl have adapted to high levels of radiation.

Natural selection requires variation, which includes structural, functional, or physiological differences between individuals.
Helpful variations increase survival and reproduction rates, eventually becoming adaptations.
Adaptation: A structure, behavior, or physiological process (e.g., camouflage or hibernation) that aids survival and reproduction in a specific environment.
Mimicry: A type of adaptation where a harmless species resembles a harmful one. For instance, the edible Viceroy butterfly mimics the appearance of the inedible Monarch butterfly to avoid predators.

Variation arises from genetic differences created through meiosis, sexual reproduction, and mutations.
Mutations: Random changes in DNA that serve as the only source of new genetic information. To be inherited, they must occur in a gamete.
Selective Advantage: A beneficial mutation that improves an organism's chances of survival, often in a changing environment.
Example: A random mutation in bacteria (which can double their population in approximately $10\,\text{minutes}$ ) may provide a benefit that allows the entire population to survive.

Selective Pressure: Environmental conditions (living factors like predators or non-living factors) that select for or against certain characteristics.
Example: Antibiotics act as a selective pressure, favoring bacteria with resistance genes.
Natural selection is situational; it has no fixed direction, and the utility of a trait depends on the environment.
Fitness: The relative contribution an individual makes to the next generation by producing surviving offspring.
Survival of the Fittest: Describes how the fittest organisms leave the most offspring and win the struggle for survival.

Artificial Selection: Selective pressure exerted by humans to modify species for desirable traits over generations.
Examples: Dog breeding, crops, and livestock like cows bred to produce more milk.