Evolution as Genetic Change

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Evolution Noun

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[ev-uh-loo-shun]

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Evolution

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A change in the allele frequencies within a population over successive generations, leading to descent with modification.

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Example: A common ancestor finch evolves into different species, each with a unique beak shape adapted to a specific food source like seeds, cacti, or insects.

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Natural Selection Noun

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[nach-er-ul suh-lek-shun]

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Natural Selection

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The process where organisms with favorable inherited traits are more likely to survive and successfully reproduce.

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Example: This diagram shows natural selection by illustrating how antibiotics kill non-resistant bacteria, allowing the few resistant bacteria to survive, reproduce, and become dominant.

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Allele Frequency Noun

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[uh-leel free-kwen-see]

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Allele Frequency

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The relative proportion of a specific allele at a particular locus in a population's gene pool.

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Example: This image shows a population of pea plants with different gene combinations (alleles). By counting the 'W' and 'w' alleles, you can calculate their frequency.

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Genetic Drift Noun

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[juh-net-ik drift]

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Genetic Drift

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Random fluctuations in allele frequencies from one generation to the next, which is more pronounced in small populations.

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Example: This diagram shows a "bottleneck event," where a random event drastically reduces a population, changing its genetic makeup by chance, which is a form of genetic drift.

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Founder Effect Noun

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[foun-der uh-fekt]

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Founder Effect

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A loss of genetic variation that occurs when a new population is established by a small number of individuals.

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Example: A small group of butterflies (founders) separates from a large, diverse parent population. By chance, the new population has a different mix of traits (colors).

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Bottleneck Effect Noun

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[bot-l-nek uh-fekt]

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Bottleneck Effect

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A sharp reduction in a population's size due to environmental events, resulting in reduced genetic diversity.

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Example: This diagram shows a random event (the bottleneck) drastically reducing a population, leaving a smaller, less genetically diverse group of survivors to form a new population.

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Gene Flow Noun

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[jeen floh]

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Gene Flow

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The transfer of genetic material from one population to another through the migration and interbreeding of individuals.

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Example: A butterfly from a population of white butterflies moves to a population of pink butterflies, introducing its genes and changing the genetic makeup of the new group.

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Mutation Noun

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[myoo-tey-shun]

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Mutation

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A permanent alteration in the nucleotide sequence of an organism's DNA, which can create new alleles.

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Example: The image shows a change in a gene's DNA sequence (mutation) which results in the creation of an abnormal protein instead of a normal one.

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Genetic Equilibrium Noun

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[juh-net-ik ee-kwi-lib-ree-um]

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Genetic Equilibrium

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A condition in which a population's allele and genotype frequencies remain constant from generation to generation.

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Example: This diagram shows how allele frequencies (p and q) from parents result in predictable and stable genotype frequencies (p², 2pq, q²) in offspring, representing a state of genetic equilibrium.

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Adaptation Noun

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[ad-ap-tey-shun]

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Adaptation

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An inherited trait that enhances an organism's ability to survive and reproduce in its specific environment.

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Example: This image shows how different color variations of stick insects are adapted to blend in with different plants, making them harder for predators to see.