ecosystems. realm of ecology organisms populations communities ecosystem biosphere
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Ecosystems
Realm of
Ecology
Organisms
Populations
Communities
Ecosystem
Biosphere
Realm of Ecology
• Species– All organisms of the same kind that are
genetically similar enough to breed in nature and produce live, fertile offspring
• Population– All the members of a species living in an area at
the same time
Realm of Ecology, cont.
• Community– All of the populations of organisms living and
interacting in a particular area
• Ecosystem– Composed of a biological community and its
physical environment
Ecosystems
• Ecosystem– A community of different species interacting
with one another and with their nonliving environment
• Can be small or large, e.g. a stream or Great Plains• Can be natural or artificial, e.g. cropfields
• All of the Earth’s ecosystems together make up the biosphere
Biodiversity
• The forms of life that can best survive the variety of conditions currently found on earth
• Types of Biodiversity– Genetic Diversity– Species Diversity– Ecological Diversity
Components of Ecosystems
• Biotic (living components)– Producers = make their own food from compounds
obtained from their environment• Photosynthesis = capturing sunlight to make sugars
• 6CO2 + 6H2O + sun C6H12O6 + 6O2
– Consumers = get their energy and nutrients by feeding on other organisms
• Aerobic respiration = uses oxygen to convert organic nutrients into carbon dioxide and water
• C6H12O6 + 6O2 6CO2 + 6H20 + energy
Types of Consumers
• Herbivores– Plant eaters– Primary consumers– Feed directly on producers
• Carnivores– Meat eaters– Feed on other consumers– Secondary and tertiary consumers
Types of Consumers, cont.
• Omnivores– Eat both plants and animals
• Scavenger– Feed on dead organisms
• Decomposers– Bacteria and fungi– Complete the final breakdown and recycling of
organic materials
Components of Ecosystem
• Biotic (living components)
• Abiotic (nonliving components)– Sunlight– Temperature– Precipitation– wind
Major components of an ecosystem in a field
Major components of a freshwater pond ecosystem
How does energy flow through ecosystems?
• Food chain– The sequence of organisms, each of which is a source
of food for the next
– Energy enters most ecosystems as high quality sunlight, which is converted to nutrients by producers. The energy is then passes on to consumers.
– As each organism uses the high-quality energy in its food to move, this energy is converted into low-quality heat (2nd law of thermodynamics)
Model of a Food Chain
Food Chain
• Trophic Level– All organisms that are the same number of
energy transfers away from the original source of energy that enters an ecosystem
• Producers = 1st trophic level• Primary consumers = 2nd trophic level• Secondary consumers = 3rd trophic level
• But real ecosystems are more complex than this …
Food Web
• Most consumers feed on more than one type of organism
• Food web = complex network of many interconnected food chains
Food Web
Energy Transfer in a Food Web
• In a food chain or web, energy is transferred from one trophic level to another, with some usable energy degraded and lost to the environment as heat.
• At each successive trophic level, some of the available biomass isn’t digested and expelled as waste
• Only a small portion of what is eaten is converted into an organism’s biomass, and the amount of usable energy available to each successive trophic level declines (80-90% is lost)
Biomass Transfer
Pyramid of Energy Flow
• A diagram representing the flow of energy through each trophic level in a food chain or web
• With each energy transfer, only a small part (typically 10%) of the usable energy entering one trophic level is transferred to the organisms at the next trophic level
Generalized pyramid of energy flow
Energy Pyramid
Energy Pyramid for Grassland