Ecology Midterm Review

Ecology - Midterm Review

• Ecology is the scientific study of interactions among and between organisms and their physical environment.
• Levels of organization:
  • Individual organism
  • Population (group of individuals of the same species)
  • Community (assemblage of different populations)
  • Ecosystem (organisms and their physical environment)
  • Biome (group of ecosystems)
  • Biosphere (entire planet)
• Population: A group of individuals belonging to the same species in the same area.
• Community: An assemblage of different populations living together in a defined area.
• Ecosystem: All organisms living in a place, along with their physical environment.
• Biome: A group of ecosystems that share similar climates and typical organisms.
• Biosphere: The entire planet with all organisms and physical environments.
• Biotic factors: Living things (plants, animals, bacteria, fungi).
• Abiotic factors: Non-living things (sunlight, heat, precipitation, humidity, wind, soil type).
• Primary producers (autotrophs): Organisms that make their own food through photosynthesis (plants, algae).
• Consumers (heterotrophs): Organisms that rely on other organisms for energy and nutrients (herbivores, carnivores, omnivores, scavengers, decomposers).
• Carnivores: Kill and eat other animals (snakes, dogs, cats).
• Scavengers: Consume carcasses of dead animals (vultures).
• Decomposers: Break down dead organisms (bacteria, fungi).
• Energy flow: Energy flows through an ecosystem in a one-way stream from producers to consumers.
• Food chain: A series of steps where organisms transfer energy by eating and being eaten (producers → herbivores → carnivores).
• Food web: A complex network of interconnected food chains.
• Ecological pyramids: Show the relative amount of energy or matter at each trophic level.

Ecosystem Processes

• Competition: Species compete for resources; competition shapes communities by causing species to divide resources and determine the number and kinds of species. Organisms can share the same habitat but not the same niche.
• Predator-prey relationships: Predator captures and feeds on prey.
• Symbiosis: Close relationship between two species, including parasitism (+/-), mutualism (+/+), and commensalism (+/0).
• Parasitism (+/-): One organism benefits and the other is harmed. (e.g., tapeworms)
• Mutualism (+/+): Both organisms benefit.
• Commensalism (+/0): One organism benefits, while the other is neither harmed nor helped.
• Ecological succession: a series of more-or-less predictable changes that occur in a community over time. - Primary succession: Succession in an area with no remnants of a previous community (e.g., volcanic explosions). - Secondary succession: Succession in an existing community that has been disturbed (e.g., wildfire).
• Carrying capacity: The number of organisms that the environment can support. Limiting factors determine carrying capacity.

Biodiversity and Environmental Concerns

• Biodiversity: The total of all genetically-based variation in organisms.
• Threats to biodiversity: Altering habitats, hunting, introducing invasive species, pollution.
• Conservation efforts: Protecting individual species, preserving habitats and ecosystems.
• Renewable resources: Naturally replaceable resources (e.g., water).
• Non-renewable resources: Resources not naturally replaceable (e.g., coal, oil, natural gas).
• Air pollution: Smog, acid rain, greenhouse gases (e.g., carbon dioxide), particulates.
• Acid rain: Forms from air pollutants reacting with water in the atmosphere.
• Greenhouse gases: Gases that contribute to global warming.
• Ozone depletion: Exposes humans to more UV radiation, increasing the chances of skin cancer.
• Global warming: Caused by increased carbon dioxide in the atmosphere (e.g. , burning fossil fuels, deforestation).
• Water cycle: Water continuously moves between oceans, atmosphere, and land. (Evaporation, condensation, precipitation, transpiration, accumulation, run-off)
• Nutrient cycles (Carbon, nitrogen, phosphorus): Processes by which nutrients are recycled and used by different organisms.

Evolution

• Evolution: Change in species over time; process by which organisms have descended.
• Natural selection: The process by which organisms with traits best suited to their environment are more likely to survive and reproduce and pass those traits to offspring.
• Natural variation: Differences among individuals within a species.
• Speciation: The formation of new species.
  • Allopatric speciation: Populations evolve into separate species because of geographical isolation.
  • Sympatric speciation: Populations evolve into separate species without geographic isolation.
  • Parapatric speciation: Formation of new species within the same geographic area.
• Divergent evolution (adaptive radiation): Species become more different.
• Convergent evolution: Different species evolve in similar ways because of similar selective pressures.
• Coevolution: Two or more species evolve in response to each other.
• Punctuated equilibrium: Long periods of no change in a species followed by short periods of rapid change.
• Gradualism: Species slowly evolve over long periods of time.
• Homologous structures: Structures that are similar because of common ancestry.
• Vestigial structures: Structures that have lost most or all of their original function.
• Adaptation: Characteristics that help an organism survive in its environment.