chapter 13 principals of ecology. ecology study of interactions between organisms and their...
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Ecology
• Study of interactions between organisms and their environments
• Reveals relationships between living and nonliving parts
• “ecology” termed by Ernst Haeckel to encourage scientists to study these relationships
Organisms
• An individual• Depend on others for food, shelter,
reproduction, protection• Can interact with others of same
species or different species• Can interact with abiotic factors
Populations
• Organisms of the same species that interbreed and live in the same area
• Compete for food, water, mates, etc.• Sharing resources determines
distances between populations
Communities
• Interacting populations• Includes different species that live in
the same area• Change in one population affects the
entire community
Ecosystem
• Interactions of populations and abiotic factors in a community
• 3 types–Terrestrial–Aquatic–saltwater
Biome
• Major regional or global community of organisms
• Characterized by climate conditions and plants
The living environment
• Biosphere – portion of earth that supports life– Includes land, air, fresh and salt water–Extends from highest part of
atmosphere to bottom of ocean• Biotic factors – all living factors in the
environment
The nonliving environment
• Abiotic factors – nonliving parts of the environment– Includes air currents, temperature,
moisture, light, and soil–Can determine which species survive in
a particular area
Biodiversity
• Variety of living things in an ecosystem• Amount of biodiversity depends on many
things such as temperature and moisture• Tropical rain forests account for >50% of
the world’s plants and animals• Rain forests and barrier reefs are “hot
spots” and are richly diverse
Keystone species
• Have a large effect on its ecosystem• May hold the dynamic ecosystem together• They form a complex web of life• Loss of the keystone species affects all
species in that ecosystem
Obtaining energy
• Producers (autotrophs) get their energy from nonliving sources to make their own food– Sunlight or chemicals (chemosynthesis)
• Consumers (heterotrophs) get their energy by eating other organisms
• Sun is the ultimate source of energy for all organisms
Food chains
• Links species by their feeding relationships
• Shows a sample of links that begin with a single producer
• Model used to show passage of matter and energy through the ecosystem
• Arrows indicate energy flow• No more than 5 links
Heterotrophs
• Depend on autotrophs for food• Herbivores eat only plants• Carnivores eat other animals• Omnivores eat plants and animals• Detritivores eat dead organic matter• Decomposers break down organic
matter into simpler substances
Selective eaters
• Specialists – eat primarily one specific organism or a very small variety of organisms
• Generalists – have a varying diet
Trophic levels
• Feeding steps in the passage of energy and materials
• Do not show all relationships
Food webs
• Show complex relationships in an ecosystem
• Expresses all possible relationships at each trophic level
Water (hydrologic) cycle
• Water on earth is liquid or solid; in atmosphere it’s gas
• Steps– Precipitation falls to the ground– Water flows into lakes, rivers; can be
absorbed into soil; most will feed the oceans– Some water evaporates and enters the
atmosphere; released from plants by transpiration
– Condensation produces precipitation
Oxygen cycle
• Organisms need oxygen for cellular respiration
• Plants release oxygen during photosynthesis
• Oxygen is also released by cycling of other nutrients like carbon, nitrogen, and phosphorous
Carbon forms
• Carbon dioxide in the atmosphere• Bicarbonate dissolved in water• Fossil fuels• Carbonate rocks (limestone)• Dead organic matter
Carbon cycle
• Steps–Plants use CO2 to make their food
–Animals eat plants, release CO2 when they breathe or die
–Decay with NO oxygen makes oil–Burning oil releases carbon dioxide
Nitrogen cycle
• Gaseous nitrogen makes up 78% of air• Lightning / bacteria convert nitrogen gas to
useable nitrogen for organisms (nitrogen fixation)
• Steps– Plants absorb nitrates– Animals eat plants and make proteins– Death / decay return nitrogen to soil– Breakdown of nitrates by bacteria return
nitrogen to the atmosphere
Phosphorous cycle
• Steps– Phosphorous released by weathering of rocks–Plants absorb phosphorous–Animals eat plants–Death / decay returns phosphorous to
soil and water–Phosphates can also be made into
rocks; released by erosion
Ecological pyramids
• Depict energy conversions in an ecosystem
• 1st level represents producers• Higher levels are stacked on lower
levels • Sun is energy