Ecology chapters 2-5
Ecology ( oikos: home) The scientific study of the interactions of organisms
with their environments
Factors
Abiotic and biotic factors drive natural selection
The organism that best fits the environment has the advantage to pass on it’s
genes
Key Abiotic Factors: Sunlight, Water, Temperature, Soil, Wind, Sever
Disturbances
Organisms/Environment Interaction
Organism: Single organism
Population: Single species
Community: All living organisms
Ecosystem: Abiotic & Biotic
Biome: Large group of ecosystems that share the same climate
Biosphere: Earth’s ecosystem
Ecosystem Interactions
Habitat: Area where an organism lives
Niche: An organisms role in the environment (Food, shelter, reproduction)
Biome, ecosystem, habitat, niche
Competition
Competitive exclusion principle: No two species can occupy the same niche at
the same time.
Interspecific: Competition between different species
Intraspecific: Competition between individuals of the same species
Predation Adaptations
Predation: One organism pursues and consumes another organism
Coevolution: When one organism changes the organism that depends on it must
change also.
Camouflage (crypsis)
Chemical defense (aposmatic)
Batesian mimicry
Symbiosis
Parasitism: One benefits, one is harmed
Commensalism: One benefits, other is nether helped or harmed
Mutualism: Both benefits
Energy Flow & Chemical Cycling
Energy flow: The passage of energy through an ecosystem
Energy must be added
Chemical cycling: The circular movement of materials within an ecosystem
Chemicals are recycled
Energy in an ecosystem
Autotrophs: Collects energy from sunlight or inorganic substances to produce
food
Heterotrophs: energy from consuming other organisms
Herbivore: Eats only producers (plants)
Carnivores: Eat other heterotrophs
Omnivours: Eat heterotrophs and autotrophs
Detritovors: Eat dead organisms (worms)
Decomposers: Final release of chemicals (fungus)
Trophic Structure
Food chain: The sequence of food transfer from trophic level to trophic level
Producers, primary consumers, secondary consumers, tertiary consumers,
quaternary consumers
Detritivours, decomposers
Food Chain vs Food Web
Food web: Network of interconnected food chains
Everything is dependent on other organisms
Energy Pyramid
Energy supply limits the length of the food chain
Biomass: The amount of organic matter in an ecosystem
Cycles in the Biosphere
Matter: Anything that takes up space and has mass
Nutrient: Chemicals that an organism must obtain from the environment to
sustain life
Biogeochemical cycles: Water, carbon, nitrogen phosphorus
Global Water Cycle
Driven by heat from the sun
Three major processes: Precipitation, Evaporation, Transpiration
Carbon Cycle
Cycle of photosynthesis and cellular respiration
Plants take in CO2 from the atmosphere and convert it to organic material.
Animals take in organic material and release CO2
Nitrogen Cycle
Atmospheric nitrogen can not be taken directly by animals
Certain plants and bacteria must convert it to a form animals can take in
Nitrates
Community Ecology
Range of tolerance: The variations of physical & chemical factors that
support a population
Limiting factors: Factors that sets the carrying capacity of the population
Ecological Succession
Primary succession - new environments (Volcanoes, glaciers, strip mines)
Secondary succession - communities were destroyed or displaced
Fires, farming
Climax community - forest
Climate
Regional climate influences the distribution of biological communities
Climate often determines the distribution of communities
Earth's global climate patterns are largely determined by the input of solar
energy and the planet's movement in space
Microclimate: Small-scale differences in a climate (Under a rock or log)
Climate Distribution
Earth’s tilt causes the seasons
Tropics: Between 23.50 north and 23.50 south
Temperate zone: Latitudes between tropics and arctic circle
Polar zones: North of 66.50 N & south of 66.50 S
Wind Patterns
Doldrums: Air currents rising from the equator causes area of light winds
(horse latitudes)
Trade winds: Descending air mass heading back to equator
Prevailing winds: combined effects of rising and lowering air masses
Westerlies: Winds from west to east
Ocean Currents
Greenhouse Effect
Greenhouse effect: The trapping of heat by gasses in the upper troposphere
Greenhouse gasses: Water vapor, carbon dioxide, methane, and nitrous oxide
Natural occurrence
Allowed life on Planet Earth
Excess gasses from burning fossil fuels is causing global warming
Biomes
Biomes are major terrestrial ecosystems that cover large regions of the Earth
Tropical forest, Savanna, Desert, Chaparral, Temperate grassland, Temperate
deciduous forest, Coniferous forest, Tundra,
Tropical Rain Forest
Equatorial, 11-12 hours daylight, Greater than 200 cm of rain per year, Most
complex biome, Temperature: 24oC – 27oC
Savanna
Precipitation: 50-130 cm, Temperature: 20oC-30oC, Grasses & scattered trees,
Frequent fires, Large herbivores
Desert
Regions of descending air (30o north & 30o south), Precipitation: 2-26 cm,
Temperature: high 20oC, 49oC ,low -18oC, 10oC, Warm days cold nights, Rain
Shadow,Rate of evaporation exceeds precipitation
Chaparral (shrubland)
Precipitation: 38-100 cm, Temperature: 10oC – 40oC, Dense, spiny shrubs, Cool
ocean currents, Mild rainy winters, long hot summers, Mediterranean &
southern California
Temperate Grasslands
Precipitation: 50-89 cm, Mostly treeless, cold winters, Seasonal droughts,
fires, grazing
Temperate Deciduous Forest
Precipitation: 75-150 cm, 35o to 50o latitude, Broadleaf trees (oak, beech,
hickory, maple, birch), Very cold winters, hot summers, High rain fall
Coniferous Forest
Precipitation: 30-84 cm, Cone-bearing trees (spruce, pine, fir), Taiga:
Northern (boreal) forests, Harsh winters, mild summers, Thin acidic soil,
Fire needed
Tundra
Precipitation: 15-25 cm, Permafrost, Extremely cold, Brief summer, Arctic
and alpine
Freshwater Life Zones
Littoral zone: Top shallow sunlight area from the shore to depth which rooted
plants stop growing
Limnetic zone: Open sunlight layer to the depth light can penetrate
Profundal zone: Deep open water where light cannot penetrate, low O2 levels
Benthic: Bottom of the lake
Types of Lakes
Oligotrophic: Nutrient poor lakes, Deep, Steep banks, Clear with little
sediments, Young lakes
Eutrophic: Nutrient rich lakes, Shallow, Shallow banks, Murky, Older lakes
Vertical Stratification
The photic zone is the portion of the ocean into which light penetrates
Photosynthesis occurs here
The aphotic zone is a vast, dark region of the ocean
It is the most extensive part of the biosphere
Although there is no light, a diverse and dense population inhabits this zone
Estuaries are productive areas where rivers meet the ocean
The saltiness of estuaries ranges from less than 1% to 3%
They provide nursery areas for oysters, crabs, and many fishes
They are often bordered by extensive coastal wetlands
Saltwater Life Zones
Coastal wetlands: Land areas covered with water all or part of the year
Inlets, bays, sounds, mangrove forest swamps, salt marshes
Wide fluctuations in temperature and salinity
Mangrove forest swamps
Buffers from storms, Filter water, Build new land
Marine Zonation
Neritic zone: low tide line to continental shelf
The intertidal zone is the wetland at the edge of an estuary or ocean, where
water meets land
Salt marshes, sand and rocky beaches, and tide pools are part of the
intertidal zone
It is often flooded by high tides and then left dry during low tides
Pelagic Biomes
The pelagic zone is the open ocean
It supports highly motile animals such as fishes, squids, and marine mammals
Phytoplankton and zooplankton drift in the pelagic zone
The benthic zone is the ocean bottom
It supports a variety of organisms based upon water depth and light
penetration
Coral Reefs
Coral reefs are found in warm tropical waters above the continental shelf
They support a huge diversity of invertebrates and fishes
Coral reefs are easily degraded by pollution, native and introduced predators
human souvenir hunters
Hydrothermal Vents
Openings in ocean floor that spew mineral-rich, superheated water
Primary producers are chemoautotrophic bacteria; use sulfides as energy
source
Population Characteristics
Population density: Number of organisms per unit area
Population distribution (dispersion):
Clumping (most common)
Uniform
Random
Density Factors
Density-dependent factors: Population-limiting factors whose effects depends
on population density.
Food, nest site
Density-independent factors: Abiotic factors that control population Climate,
weather
Population Growth Cycles
Boom-bust cycle: A rapid increase in population followed by a sharp decline
Usually found in a predator-pray situation
Lynx & snowshoe hares
Exponential Growth
The rate of expansion of a population under ideal conditions when the whole
population multiplies by a constant factor during constant time intervals.
Exponential growth model: Gives a picture of unregulated growth of a
population
Logistic Growth Model
A description of population growth that is slowed by limiting factors.
Population limiting factors: Environmental factors that restrict population
growth
Carrying capacity: Number of individuals that the environment can maintain
with no net increase or decrease.
World Population Growth
Overall population growth has slowed from 2.2% to 1.25%. (0.6 by 2050
predicted)
Death rate has fallen more than birth rate
~ 219,000 new people per day
97% in developing nations
China: 1.3 billion people (20%)
India: 1.1 billion people (17%)
U.S.A.: 294 million people (4.6%)
Human Population Growth
Demography: Study of population size, density, distribution, movement, birth
and death rate
Population growth rate:
Birthrate – deathrate + migration rate = PGR (%)
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Diversity
Biodiversity: The number of species in a given area
Genetic diversity: The variety of genes in the gene pool
Ecosystem diversity: The variety of ecosystems in the biosphere
Threats to Biodiversity
Background extinction: Local environmental changes cause a low number of
species to go extinct (~ 1-5 species per 1 million)
Mass extinction: Widespread sometimes global in which 25% to above 70% of the
species goes extinct
Mass depletion: Extinction rate is higher than background extinction but does
not reach mass extinction rates
Habitat destruction, Habitat fragmentation, Introduced species,
Overexploitation, Pollution
Biological magnification: The concentration of a toxin is greatly increased
the further it is passed up the food chain
Rachel Carson was one of the first to perceive the global dangers of
pesticide abuse
Carson documented her concerns in the 1962 book Silent Spring
This book played a key role in the awakening of environmental awareness
Eutrophication
Enrichment of a body of water with nutrients
Can occur naturally over long time span
Can be triggered by pollutants
Acid Precipitation
Acid rain: Sulfur & nitrogen from burning fossil fuels combine with water,
forming sulfuric and nitric acid
Mainly caused from the burning of coal for the generation of electricity,
Denatures plant enzymes, Kills fish
Conserving Biodiversity
Natural resources
Renewable resources
Nonrenwable resources
Sustainability: Using just enough resources so as not to effect the next
generation
Restoring Ecosystems
Bioremediation: Using living organisms to detoxify a polluted area
Biological augmentation: Using natural predators to a degraded ecosystem
Fixing the Problem
Focusing on hot spots
Understanding an organisms habitat
Balancing the demands for resources
Planning for a sustainable future
Buffer zones
Sustainable development
GETTING INVOLVED!!!!!!!!!!!!!