Common Ancestry

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Evolution Noun

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[ev-uh-loo-shun]

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Evolution

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The process by which living things change and adapt to their surroundings over many generations to ensure survival.

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Example: This evolutionary tree shows how different animal groups (like birds, reptiles, and mammals) branched off from a shared ancestor over time.

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Scientific Theory Noun

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[sy-en-tif-ik thee-uh-ree]

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Scientific Theory

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A well-tested, evidence-supported explanation for how a natural phenomenon works, representing the most logical scientific understanding available.

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Example: This diagram shows mantle convection driving plate tectonics. While this is a valid scientific theory, it is unrelated to the biological theory of common ancestry.

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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 beneficial genetic traits are more likely to survive, reproduce, and pass those traits on.

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Example: Different finches, descended from a common ancestor, developed unique beak shapes through natural selection to eat specific foods like insects, seeds, or fruit.

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Adaptive Radiation Noun

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[uh-dap-tiv ray-dee-ay-shun]

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Adaptive Radiation

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The rapid diversification of a group of organisms into various new forms that fill different ecological roles or niches.

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Example: A single ancestor species evolves into many new species, each adapted to a different environment or food source, like these birds with different beaks.

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Ecological Niche Noun

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[ee-kuh-loj-i-kul nich]

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Ecological Niche

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The specific role and position a species has in its environment, encompassing its interactions, diet, and habitat requirements.

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Example: An Acorn Woodpecker carves holes in a tree to store acorns, showing its unique role (niche) which includes its habitat, food, and behavior.

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Fossil Record Noun

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[fos-ul rek-erd]

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Fossil Record

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The total collection of discovered fossils which provides crucial evidence for understanding the history of life on Earth.

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Example: This diagram shows that older fossils, like coral, are found in deeper rock layers, while younger fossils, like ferns, are in shallower layers.

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Transitional Fossil Noun

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[tran-zish-uh-nul fos-ul]

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Transitional Fossil

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A fossil that displays characteristics common to both an ancestral group and its more evolved descendant group, showing evolution.

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Example: This diagram shows Archaeopteryx, a transitional fossil, with features of both its dinosaur ancestor (Compsognathus) and its modern bird descendant (chicken).

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Vestigial Structure Noun

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[ves-tij-ee-ul struk-cher]

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Vestigial Structure

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A structure or organ in an organism that has lost most or all of its original ancestral function through evolution.

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Example: A whale's skeleton contains a small pelvic bone, a remnant from land-dwelling ancestors that had legs, showing an evolutionary link to a common ancestor.

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Biogeography Noun

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[by-oh-jee-og-ruh-fee]

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Biogeography

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The scientific study of the geographic distribution of species, which provides compelling evidence for evolution and common ancestry.

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Example: Related species, like Darwin's finches, develop different traits (like beak shapes) when they are geographically separated and adapt to different environments.

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Convergent Evolution Noun

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[kun-vur-junt ev-uh-loo-shun]

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Convergent Evolution

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The process where unrelated species independently evolve similar traits as a result of adapting to similar environmental pressures.

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Example: Different ancestral lines, represented by separate arrows, independently evolve similar traits, causing them to 'converge' on a similar form or function.