bio

• Natural selection


  A theory that states that organisms better suited to their environment will thrive and thus pass their genetic characteristics
• Artificial selection


  The process in which humans select organisms with desirable traits and cause them to reproduce in the next generation
• Gene flow


  Immigration or emigration or the movement of genetic information with migration of individual from one population to another
• Genetic drift


  Changes from generation to generation in allele frequencies (the percentages of a specific version of a gene) that result from random processes
• Bottleneck effect


  The result after a random occurrence causes a population to shrink rapidly and change its allele frequencies. Example: A natural disaster can cause the bottleneck effect
• Founder effect


  The result is after a small group of a population separates and forms a new population with allele frequencies different from those of the original population
• Stabilizing selection, directional and disruptive selection have in common that they all decrease genetic variation
• Mass extinction


  An event in which at least 60 percent of the species living on Earth becomes extinct at a particular time
• Sexual selection


  The method animals use to attract mates to reproduce
• Polygenic trait


  A trait controlled by two or more genes. Example: Height
• Selective pressures


  Factors that give some organisms in a population the opportunity to reproduce and deny that opportunity to others. Example: Natural selection, sexual selection
• Mutation


  Increases genetic variety in population
• Evolution would not happen without mutation as there would be no differences for natural selection
• Fossil


  The remains of a once-living organism OR a preserved footprint left behind by an animal
• Fossil record


  The orderly collection of all known fossils that have existed throughout life's history
• Index fossil


  A fossil that is found in rocks of only one particular time period. Example: Trilobite fossils
• Homologous structure


  A physically similar structure that performs different functions in different species
• Vestigial structure


  A structure in an organism that has lost all or most of the original function it had for an ancestor. Example: A whale's pelvic bone
• Organisms with similar embryonic development are often considered to have similar ancestry
• Common ancestor


  An organism from which two or more species evolved
• DNA or protein sequences are more similar for organisms thought to be more closely related, providing evidence for evolution
• Ecosystem


  A system formed by the interaction of living organisms with the nonliving physical environment
• Biodiversity


  The number and variety of living organisms in an ecosystem or geographic area
• Species


  A group of organisms whose members can produce offspring together and whose offspring are also able to reproduce
• Population


  A group of individuals of the same species living together in the same area at the same time
• Community


  A group of organisms living together in the same region who interact with one another
• Habitat


  The place where a particular plant or animal lives, and the natural processes that maintain that area
• Abiotic


  Nonliving. Example: water, soil, sunlight and climate
• Biotic


  Living. Example: animals and plants
• Biome


  A large geographic region that has consistent weather, plants, and another organism. Example: Tundra, desert, and coral reefs
• Rainforest


  Daily precipitation, warm temp and highly productive
• Taiga and tundra


  Below freezing most of the year, unproductive
• Photic zone


  The upper region of a body of water, which receives enough light for photosynthesis
• Aphotic zone


  The lower area of a body of water, which does not receive enough light to support photosynthesis
• Littoral zone


  One of the abiotic factors in an aquatic ecosystem
• Limnetic zone


  One of the abiotic factors in an aquatic ecosystem
• Benthic zone


  The lower, dark layer of a body of water consisting of water and sediment
• Estuary


  An area where freshwater and saltwater mix
• Upwelling


  Stirring of water from the benthic zone up toward the surface
• Marine ecosystem


  Abiotic conditions: salinity, temperature, nutrient variability