The Process of Speciation

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Speciation Noun

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[spee-see-ay-shun]

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Speciation

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The evolutionary process by which populations evolve to become distinct species that are unable to interbreed and produce fertile offspring.

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Example: This image shows different finch species with unique beak shapes, a result of speciation where an ancestral species evolves into new, adapted forms.

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Gene Pool Noun

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[jeen pool]

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Gene Pool

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The total collection of genes and their different alleles that exist within a particular interbreeding population at a given time.

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Example: This diagram shows a population of frogs with different colors and then represents all their genetic variations (alleles) as a collection, defining the gene pool.

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Reproductive Isolation Noun

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[ree-pro-duk-tiv eye-so-lay-shun]

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Reproductive Isolation

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The inability of members of two populations to interbreed and produce fertile offspring, which is essential for speciation to occur.

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Example: This image shows that different flower shapes are suited for different pollinators. This physical barrier, called mechanical isolation, prevents them from interbreeding, keeping them separate species.

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Geographic Isolation Noun

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[jee-oh-graf-ik eye-so-lay-shun]

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Geographic Isolation

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A form of reproductive isolation where two populations are separated by physical barriers such as rivers, mountains, or bodies of water.

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Example: This diagram shows how finch populations on the Galapagos Islands were separated by the ocean, a geographic barrier that led to the evolution of different species.

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Temporal Isolation Noun

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[tem-per-ul eye-so-lay-shun]

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Temporal Isolation

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A form of reproductive isolation that occurs when two or more species reproduce at different times of the day or year.

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Example: In May, Species 1 is flowering and ready to reproduce, while Species 2 is still a bud, preventing them from interbreeding.

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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 traits are more likely to survive, reproduce, and pass those traits to their offspring.

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Example: Giraffes with the advantageous trait of a long neck can reach food and survive, while those with shorter necks cannot. This demonstrates survival of the fittest.

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Polygenic Traits Noun

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[pol-ee-jen-ik trayts]

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Polygenic Traits

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Traits that are controlled by two or more genes, often resulting in a continuous range of physical characteristics within a population.

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Example: The wide variety of colors, shapes, and sizes among these beetles shows variation within a population, which is often caused by polygenic traits.

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Directional Selection Noun

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[di-rek-shun-ul suh-lek-shun]

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Directional Selection

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A mode of natural selection where an extreme phenotype is favored, causing the allele frequency to shift over time in that direction.

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Example: This image shows how an environmental change caused dark moths to be better camouflaged and survive more, shifting the population's color over time.

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Founder Effect Noun

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[fown-der uh-fekt]

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Founder Effect

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A change in allele frequencies that occurs when a new population is established by a small number of individuals from a larger population.

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Example: A small group of butterflies (founders) leaves a large, diverse parent population, creating new populations with different and less varied traits by chance.

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Ecological Competition Noun

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[ee-kuh-loj-i-kul kom-pi-tish-un]

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Ecological Competition

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The struggle between two or more organisms for the same limited resources, such as food, water, or territory, within an environment.

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Example: This image shows ecological competition, where organisms struggle for resources. It compares competition within a species (intraspecific) to competition between different species (interspecific).