Diversity of Organisms (04:07)
Biodiversity is the variety of species within an environment, and can convey the health of an ecosystem. Climate, altitude, soil, and species can affect diversity. The equator regions with warm temperatures and soil, are diverse, while polar regions are not.
Life Functions of Organisms: Prokaryotes (03:34)
Organisms have unique processes for survival in an environment, such as digestion and reproduction. Archaea digest organic and inorganic compounds for energy, use flagella to move, and reproduce asexually. Bacteria are heterotrophs or autotrophs, and move with flagella.
Life Functions of Eukaryotes (03:30)
Protists are heterotrophs or autotrophs and reproduce alone or sexually. Fungi are heterotrophs with a cell wall made of chitin; they support plant growth and reproduce sexually or asexually. Plants are sexual or asexual autotrophs with cell walls; animals are heterotrophic and reproduce sexually.
Habitat destruction is a primary cause of species extinction. Organisms live in a habitat appropriate for their lifestyle. The Northern Spotted Owl prefers old growth forests; populations have greatly decreased.
Population Ecology (05:00)
A collection of species in a location can change with birth or death rate, and when individuals migrate to or from the location. A growth curve models this change, and when resources are limited, growth slows; carrying capacity reflects the population size that an environment can sustain.
Limiting Factors (01:25)
Population equilibrium depends on food supply, crowding, and predator or prey populations. These factors affect groups differently depending on population size. Weather and natural disasters affect an entire population regardless of size.
Communities and Ecosystems: Energy Cycle (02:58)
Ecosystems depend on flow of energy. The food chain begins with producers that capture sun energy; consumers eat, and decomposers break down dead material, releasing more nutrients. An energy pyramid demonstrates the decreasing energy available at each stage of the food chain.
Nutrient Cycles (05:58)
Nutrients cycle through an ecosystem. Producers absorb minerals and gases, herbivores eat plants, carnivores eat herbivores, and fungi and bacteria decompose. Water, carbon, nitrogen, and oxygen cycle through an ecosystem in unique ways.
Succession Patterns (01:36)
As energy and nutrients cycle in an ecosystem, the community changes over time. The first species to arrive are r-selected species, diverse fast growing plants, which are followed by k-selected plants which are more competitive, driving diversity down.
Effects of Change (02:22)
Human activity is one of the main causes of change in ecosystems. Dams and mining disrupt water flow and nutrient cycling, while conventional agriculture destroys biodiversity and pollutes. Population growth can alter an ecosystem through the food chain.
Global Issues (02:16)
Since the beginning of industrialization in the 1800s, global temperatures began rising. Humans have destroyed over 80% of forests, and emissions have caused the carbon dioxide concentration in the atmosphere to rise. With higher carbon content, sub-alpine forest will disappear, and shrubland will convert to forest.
Ways to Reduce Emissions (01:12)
To reduce their impact on the environment, people can reduce waste and recycle. They can exchange light bulbs for compact fluorescent bulbs. People should walk or bicycle instead of driving, and grow food.
Credits: Ecology (00:16)
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