Evolution Review — Study Materials Flashcards

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Mechanisms of Evolution

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The processes that change allele frequencies in populations over time. Major mechanisms include mutation, natural selection, sexual selection, gene flow, and genetic drift.

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Mutation

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A change in DNA sequence that can create new genetic variation. Mutations can be neutral, harmful, or beneficial and are the original source of new alleles in a population.

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Natural Selection

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A process where individuals with traits better suited to the environment tend to survive and reproduce more. Over generations, advantageous traits increase in frequency within the population.

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Sexual Selection

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A form of natural selection where traits increase an individual's mating success. Traits favored by sexual selection may improve reproductive success but not necessarily survival.

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Gene Flow

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Movement of alleles between populations through migration of individuals or gametes. Gene flow tends to reduce genetic differences between populations.

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Genetic Drift

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Random changes in allele frequencies due to chance events, especially important in small populations. Drift can lead to loss of genetic variation and fixation of alleles.

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Charles Lyell

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Geologist who proposed that Earth changes slowly over long periods, influencing Darwin's thinking on gradual biological change. His ideas supported the concept of deep time for evolution.

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Thomas Malthus

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Economist who noted that populations can grow faster than resources, creating competition. Darwin applied this idea to natural populations to explain the struggle for existence.

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Artificial Selection

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Human-directed breeding where desirable traits are chosen to produce offspring with selected characteristics. It provided a model for how selection can change species over time.

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Variation

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Heritable differences among individuals in a population. Variation is necessary for natural selection to act on and for evolution to occur.

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Competition

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The struggle between organisms for limited resources like food, mates, and territory. Competition leads to differential survival and reproduction among individuals.

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Fitness

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A measure of an individual's reproductive success relative to others in the population. Higher fitness means contributing more genes to future generations.

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Inheritance

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The transmission of genetic traits from parents to offspring. Only heritable traits can respond to natural selection across generations.

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Peppered Moths

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A classic example showing natural selection in response to environmental change; dark and light forms varied in frequency with pollution levels. Their changing frequencies illustrated adaptation to selection pressures.

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Fossil Record

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The preserved remains or traces of ancient organisms found in rock layers. Fossils document changes in life forms over time and can show transitional forms.

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Homologous Structures

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Body parts in different species that share a common ancestral origin but may have different functions. Homologies indicate common ancestry and divergent evolution.

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Vestigial Structures

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Anatomical features that have lost their original function in a species. Vestigial traits are evidence of evolutionary history and past adaptations.

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Comparative Embryology

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The study of similarities and differences in embryo development across species. Shared embryonic stages can indicate common ancestry.

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Comparative Biochemistry

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Comparison of DNA, RNA, and protein sequences and metabolic pathways across organisms. High molecular similarity supports close evolutionary relationships.

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Speciation

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The process by which one ancestral species splits into two or more distinct species. It often involves reproductive isolation and divergence in traits over time.

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Adaptive Radiation

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Rapid evolutionary diversification of a lineage into multiple species that occupy different ecological niches. Often occurs when new habitats or resources become available.

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Convergent Evolution

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Independent evolution of similar traits in unrelated lineages due to similar environmental pressures. Convergent species often develop analogous structures with similar functions.

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Analogous Structures

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Structures in different species that perform similar functions but evolved independently and do not share a common ancestral origin. They result from convergent evolution.