Unit 2 Living Things and their Environment
What is Ecology?
Sec. 3-1
Interactions and Interdependence
Ecology is a branch of science that studies interactions between organisms and between organisms and their environment.
Biosphere is the combined parts of Earth where all living things exist: land, water, atmosphere.
Levels of Organization
- Species are groups of individuals that can successfully breed and produce fertile offspring.
Downy Woodpeckers like the edges of the forest.
Hairy Woodpeckers live in the deep forest.
- Population is a group of individuals belonging to the same species living in a specified region.
This is a population of aphids.
- Communities are groups of different species living together and interacting in a defined region.
This is a community of ants and aphids getting energy from a plant.
- Ecosystem is a defined region where different populations interact and living together with the abiotic parts of their environment.
- Biome is a group of ecosystems with similar climates and dominant communities.
- Biotic factors are living things in an environment. Abiotic factors are nonliving things in an environment.
This cicada is a biotic factor.
These rocks are an abiotic factor.
Ecological organizationJ
Energy Flow
Sec. 3-2
Producers
- Main source of energy on Earth is the sun (less than 1% of sun’s energy is captured and used by living organisms)
- Some organisms can capture chemical energy.
- Energy is captured by autotrophs or producers.
- The producers or autotrophs are essential to the flow of energy through ecosystems.
- Organisms that capture energy to fuel the construction of simple inorganic or complex organic compounds include: plants, algae and certain bacteria
- Photosynthesis captures energy from the sun.
- On land, photosynthesis done by plants, in water algae and photosynthetic bacteria.
- Some chemosynthetic bacteria use energy in chemical bonds of inorganic molecules to produce carbohydrates.
Consumers
- Organisms that consume the producers or autotrophs for energy are heterotrophs or consumers.
- Many different types of consumers: herbivores, carnivores, omnivores, detritivores, decomposers
Feeding Relationships
- Energy flows through ecosystems from sun or inorganic compounds to autotrophs (producers) to heterotrophs (consumers)
- Energy stored by producers is passed along a food chain.
- When the chains intertwine they form a food web. Each step in a food chain or web is a trophic level.
Ecological Pyramids
- Amount of energy or matter in a food chain is represented in an ecological pyramid…3 types
- Energy Pyramid
Only 10% of energy from levels below moves up to the next trophic level.
- Biomass Pyramid
- Represents the total amount living tissue within a given trophic level.
- Pyramid of Numbers
- Based on the number of individuals at each trophic level
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Cycles of Matter
Sec. 3-3
Recycling in the Biosphere
Unlike the flow of energy, matter is recycled within ecosystems through biogeochemical cycles.
The Water Cycle
Nutrient Cycles
CARBON CYCLE
- Key ingredient of living things.
- Taken in by photosynthesis
- Released by cellular respiration
NITROGEN CYCLE
- Nitrogen is needed to make amino acids which form together to make proteins.
- 78% of nitrogen on Earth is nitrogen gas unusable because it is 2 atoms stuck together by a very strong triple bond.
- Lightning, volcanic action and certain bacteria turn nitrogen into forms that plants and animals can use.
PHOSPHOROUS CYCLE
- Phosphorous is essential part of DNA and RNA molecules.
- Not a very common in the biosphere
- Does not enter atmosphere, but stays in land, rock, soil and sediment
What Shapes an Ecosystem?
Sec. 4-2
Biotic and Abiotic Factors
- Biotic factors are all the living things within an ecological community.
- Abiotic factors are all the physical or nonliving factors in an ecological community.
- Biodiversity is all the species living within an ecological community.
- Loss or reduction of biodiversity weakens an ecosystem.
- Loss prevents recovery after disturbance
- Biotic and abiotic factors determine the growth and productivity of the biodiversity within and ecological community.
- Habitat is where the living things can grow and reproduce.
The Niche
- Niche is the range of physical and biological conditions that organisms use in order to exist.
- Includes its place in the food web, range of temperatures it can survive
Community Interactions
- Competition occurs when the same or different species vie for a natural resource.
- Competitive exclusion principle states that no 2 species can occupy the same niche at the same time.
- Predation occurs when one organism captures and feeds upon the other.
- Symbiosis occurs when 2 species live closely with one another. There are 3 types:
- Mutualism occurs when both species benefit. Example would be flowers and bees.
- Commensalism occurs when one species benefits and the other is neither harmed nor helped. Example would be barnacles on whales.
- Parasitism is when one species feeds upon another (host). Example would be a tick on your dog.
Ecological Succession
- Predictable change over time
- Altered by human disturbance such as clearing a forest or eradicating a part of the food web.
- Example….
- What if the producers are eradicated from an ecosystem?
- Herbivores?
- Predators?
- Decomposers?
- Scavengers?
- Example….
- Primary succession occurs where nothing previously existed other than abiotic factors such as rock.
Pioneer species are the first to inhabit areas of primary succession: lichens, moss
- Secondary succession occurs where living things have previously existed.
Secondary might occur after a forest fire.
Factors such as pollution or introduction of nonnative species might alter secondary succession and destroy an ecosystem.
Case of the Missing Hawk
- In 1700’s in PA, bounty offered on
crows hawks owls goshawks
S P P P
- By 1935 trees were mysteriously dying around the Reading reservoir
- close inspection…trees were ringed
- meadow mice were the culprit
- hawks (predators to the mice) were eliminated by the bounty offers from years past
The graph above shows the general relationship between populations of predator and prey.
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Biomes
Sec. 4-3
The Earth is characterized by ecologists by separate biomes. Biomes are terrestrial communities that have similar soil and climate, therefore similar plants and animals.
- Different plants tolerate various types of conditions to successfully photosynthesize and reproduce.
- Availability of water and temperatures are the limiting factors for plant growth.
- Animals move in to eat the plants that are growing. Different animals also have various tolerances to temperature and availability of water.
- Even within biomes there can be varying microclimates, based upon conditions in a small area.
Major Terrestrial Biomes
-Temperate Deciduous Forest
Where?
Precipitation?
Soil?
Dominant species?
-Temperate Grasslands
Where?
Precipitation?
Soil?
Dominant species?
-Tropical Rainforest
Where?
Precipitation?
Soil?
Dominant species?
-Tropical Savanna
Where?
Precipitation?
Soil?
Dominant species?
-Taiga
Where?
Precipitation?
Soil?
Dominant species?
-Tundra
Where?
Precipitation?
Soil?
Dominant species?
-Desert
Where?
Precipitation?
Soil?
Dominant species?
Climate change can influence the range of biomes. For example, warmer temperatures and decreased availability of water can extend deserts into temperate grasslands.
Within most biomes, there are aquatic ecosystems characterized by depth, flow, temperature, chemistry of water.
-Freshwater ecosystem
- Lotic (flowing water)
- Creek or stream
- River
- Lentic (still water)
- Pond
- Wetlands
- Lakes
-Marine ecosystems
- Estuaries
Merrimac River as it flows to the Atlantic Ocean
- Intertidal zones
Intertidal Salt Marsh west of Plum Island, MA
Plum Island, MA one week before Hurricane Sandy 2012
- Coral reefs
- Open ocean
- Benthic zone
