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Patterns of Evolution

Patterns of Evolution. Genetic Drift. Random change in allele frequency In small populations, individuals that carry a particular allele may leave more descendants than other individuals, by chance Over time, these occurrences can cause an allele to become common in a population.

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Patterns of Evolution

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  1. Patterns of Evolution

  2. Genetic Drift • Random change in allele frequency • In small populations, individuals that carry a particular allele may leave more descendants than other individuals, by chance • Over time, these occurrences can cause an allele to become common in a population

  3. Isolating Mechanisms • As new species evolve, populations become reproductively isolated from each other. • Reproductive • Behavioral • Geographic • Temporal

  4. Reproductive Isolation • When the members of two populations cannot interbreed and produce fertile offspring.

  5. Behavioral Isolation • Occurs when two populations are capable of interbreeding but have differences in courtship rituals or other reproductive strategies that involve behavior

  6. Geographic Isolation • Two populations are isolated by geographic barriers such as rivers, mountains, or bodies of water.

  7. Temporal Isolation • Two or more species reproduce at different times.

  8. Macroevolution • Refers to large-scale evolutionary patterns and processes that occur over long periods of time.

  9. Extinction • 99% of all species that have ever lived are extinct • Some mass extinctions have occurred killing off entire ecosystems. • These were believed to have occurred due to a collapsing environment. • These extinctions left room for new species to evolve.

  10. Adaptive Radiation • Occurs when a single species or a small group of species has evolved, through natural selection, into diverse forms that live in different ways. • Ex: Darwin’s finches: more than a dozen species evolved from a single species.

  11. Convergent Evolution • Adaptive radiation can cause the production of unrelated organisms that look remarkably similar • May occur when animals evolve in separate locations under similar conditions and they develop the need for similar structures. • Ex: swimming animals have a streamline body (sharks, fish, dolphins, and penguins)

  12. Divergent Evolution • When species that were similar become different. • Same as adaptive radiation.

  13. Coevolution • The process by which two species evolve in response to changes in each other over time • Ex: a flower changes color, odor, or scent over time, so the pollinator may also change

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