Unit 3_Evolutionary Mechanism and Natural Selection

These vocabulary flashcards cover the fundamental principles of evolution by natural selection, types of selection, adaptations, speciation, and the mechanisms of evolution as described in the lecture notes.

Charles Darwin

Scientist who observed that different islands in the Galápagos had slightly different varieties of animals suited for their particular environment.

Natural Selection

The process of elimination where organisms with traits best adapted for the current environment survive to breed and pass on their genes.

Biological fitness

The ability of an organism to survive AND reproduce, thereby passing on its genes to the next generation.

Selection pressure

The driving force provided by nature that pushes a population toward exhibiting the characteristics that make the organism most fit.

Genetic Variation

The inherited differences in DNA within a population, caused by mutations, meiosis (crossing over), and random mate selection/fertilization.

Overproduction

The tendency of a species to produce more individuals than can survive to maturity, which increases the chance that some will survive.

Diversifying selection

Also known as disruptive selection, a type of selection where the intermediate variation is selected against and the extremes are selected for.

Stabilizing selection

A type of natural selection where the intermediate variation or average trait in the population is selected for.

Directional selection

A type of natural selection where one extreme variation or characteristic in the population is selected for, such as long-necked giraffes.

Camouflage

A type of morphological adaptation that allows an organism to blend into its environment.

Mimicry

A morphological adaptation where one species evolves to resemble another species.

Behavioral Adaptations

Learned behaviors passed to future generations, such as monkeys using tools, birds migrating, or bears hibernating.

Speciation

The evolutionary process where one species gives rise to a new, distinctly different species.

Reproductive isolation

The inability of an organism to reproduce with a related species, often leading to speciation.

Geographic barriers

Physical separations, such as rivers, volcanoes, or island isolation, that prevent populations from breeding.

Temporal barriers

A factor that causes speciation when mating is prevented due to differences in timing, such as dragonflies mating at different times of the year.

Behavioral barriers

Isolation between populations due to differences in mating calls, courtship rituals, or preferred habitat.

Physiological barriers

Reproduction prevention due to the way the body functions, such as reproductive structure incompatibility or morphological size differences.

Genetic barriers

Barriers where egg and sperm are incompatible, the offspring never develops, or the resulting offspring are sterile.

Gene Pool

The collection of all the different genes, including all versions or alleles, within a population.

Recombination

Also known as crossing over, the mechanism that leads to genetic variation by shuffling DNA during meiosis.

Gene Flow

The movement of individuals and alleles in and out of populations, through processes like migration or seed distribution.

Genetic Drift

The effect of chance events on the gene pool of a population, which includes the Founder effect and the Bottleneck Effect.

Founder effect

A type of genetic drift that occurs when a small group splinters off to start a new colony, skews the gene pool of the new population.

Bottleneck Effect

A type of genetic drift where a disaster reduces a population to a small number, causing alleles to be lost and narrowing the gene pool.