Ecologists study environments at different levels of organization.
• Ecology is the study of the interactions among living things, and between living things and their surroundings.
3.1 What is Ecology?
OrganismOrganism
• An organism is an individual living thing, such as an alligator.
3.1 What is Ecology?
OrganismOrganism
PopulationPopulation
• A population is a group of the same species that lives in one area.
3.1 What is Ecology?
OrganismOrganism
PopulationPopulation
Community
Community
• A community is a group of different species that live together in one area.
3.1 What is Ecology?
Organism Organism
Population Population
Community Community
Ecosystem Ecosystem
• An ecosystem includes:
1) Abiotic factors – nonliving components of an ecosystem (sunlight, precipitation, temperature, water, atmosphere etc)
2) Biotic factors – living components of an ecosystem
(organisms)
3.1 What is Ecology?
OrganismOrganism
PopulationPopulation
Community
Community
Ecosystem
Ecosystem
Biome• A biome is a major regional or global community of organisms characterized by the climate conditions and plant communities that thrive there.
3.1 What is Ecology?
OrganismOrganism
PopulationPopulation
Community
Community
Ecosystem
Ecosystem
Biome• Biosphere is the part of Earth where
life exists.
3.1 What is Ecology?
Producers provide energy for other organisms in an ecosystem.
• Producers are also called autotrophs because they make their own food.
• Photosynthesis in most producers uses sunlight as an energy source.
• Chemosynthesis in prokaryote producers uses chemicals as an energy source.
3.2 Energy Flow
Producers provide energy for other organisms in an ecosystem.
• primary productivity – the rate at which solar energy is converted into organic compounds (kcal/m2/year) through photosynthesis
• gross primary productivity – total amount of energy produced, including the energy used by the plants for their own cellular respiration
• net primary productivity – rate at which plants store energy that is not used in plant respiration; material that is actually available as food for consumers
3.2 Energy Flow
• Consumers are also called heterotrophs because they feed off of different things.– Herbivores eat only plants.– Carnivores eat only animals.– Omnivores eat both plants and animals.– Detrivores (scavengers) eat dead organic matter.– Decomposers are detritivores that break down organic matter into simpler compounds.
3.2 Energy Flow
• Trophic levels are the feeding levels which shows how energy flows in an ecosystem.
(decomposers)
(carnivores)
(carnivores)
(herbivores)
3.2 Energy Flow
• Energy is lost as heat or used by the organism through each trophic level
• Only 10% of energy is passed from one trophic level to the next = “10% Rule”
3.2 Energy Flow
KEY CONCEPT Food chains and food webs model the flow of energy in an ecosystem.
3.2 Energy Flow
A food chain is a model that shows a sequence of feeding relationships.
Algae
ZooplanktonSmall Fish
SquidShark
Algae
ZooplanktonSmall Fish
SquidShark
3.2 Energy Flow
A food web shows a complex network of feeding relationships and energy flow.
• An organism may have multiple feeding relationships in an ecosystem.
• A food web is made up of interconnected food chains.
3.2 Energy Flow
3.2 Energy Flow
KEY CONCEPT Matter and element essential for life cycle through the ecosystem.
3.3 Cycles of Matter
A biogeochemical cycle is the movement of a particular chemical through an ecosystem.
• Cycling maintains a balance in the environment.
• 4 cycles to investigate:
1) Water cycle2) Carbon cycle3) Nitrogen cycle4) Phosphorus cycle
3.3 Cycles of Matter
Water cycle• The hydrologic, or water, cycle is the circular pathway of water on
Earth.• Organisms all have bodies made mostly of water.
precipitationcondensation
transpirationevaporation
water storagein ocean
surfacerunoff
lake
groundwater
3.3 Cycles of Matter
– Carbon is the building block of life.– The carbon cycle moves carbon from the atmosphere, through the food
web, and returns to the atmosphere.– Carbon is emitted by the burning of fossil fuels.
Carbon cycle
3.3 Cycles of Matter
Carbon cycle
fossil fuels
photosynthesis
carbon dioxidedissolved in water
decompositionof organisms
respiration
carbondioxidein air
photosynthesis
combustionrespiration
Carbon cycle
3.3 Cycles of Matter
– The nitrogen cycle mostly takes place underground.– Atmospheric nitrogen (N2) makes up nearly 78% of air; but organisms
cannot use it in that form.
Nitrogen cycle
– Some nitrogen-fixing bacteria convert gaseous nitrogen into ammonia through a process called nitrogen fixationso plants can use it.
– Some nitrogen-fixing bacterialive in nodules on the roots of plants; others live freely inthe soil.
3.3 Cycles of Matter
nitrogen inatmosphere animals
denitrifyingbacteria
nitrifyingbacteria
nitrifyingbacteria
ammonium
ammonificationdecomposers
plant
nitrogen-fixingbacteria in soil
nitrogen-fixingbacteria in
roots
nitrates
nitrites
Nitrogen cycle
3.3 Cycles of Matter
– The phosphorus cycle takes place at and below ground level.– Phosphate is released by the weathering of rocks. – Phosphorus moves through the food web and returns to the soil during
decomposition.
Phosphorus cycle
3.3 Cycles of Matter
geologic upliftingrain
weathering ofphosphate from rocks
runoff
sedimentationforms new rocks
leachingphosphate in solutionanimals
plants
decomposers
phosphatein soil
Phosphorus cycle
3.3 Cycles of Matter
KEY CONCEPT Climate is a key abiotic factor that affects the biosphere.
4.1 The Role of Climate
Climate is the prevailing weather of a region.
• Climate is the long‐term pattern of weather conditions.– average temperature– precipitation– relative humidity
• Key factors shape an area’s climate.– temperature– sunlight– water– wind
4.1 The Role of Climate
Earth has three main climate zones.
• The three main zones are the polar, tropical, and temperate climates.– polar climate: the far northern and southern regions of Earth
– tropical zone: surrounds the equator
– temperate zone: the wide area in betweenthe polar and tropical zones
4.1 The Role of Climate
A habitat differs from a niche. • Habitat
– physical area in which an organism lives• Niche
– each species plays a specific role in an ecosystem – niche includes the species’ habitat, feeding habits, behaviors etc.
4.2 What Shapes an Ecosystem?
KEY CONCEPT Organisms interact as individuals and as populations.
4.2 What Shapes an Ecosystem?
Competition and predation are two important ways inwhich organisms interact.
• Competition occurs when two organisms fight for thesame limited resource.– Intraspecific competition: within the same species
– Interspecific competition:between two differentspecies
4.2 What Shapes an Ecosystem?
• Predation occurs when one organism feeds on another.as population of prey rises, there will be a corresponding rise in predator population and vice versa prey and predator species coevolve
4.2 What Shapes an Ecosystem?
Symbiosis is a biological relationship where organisms of 2 different species live in a close association
• Three types of symbiotic relationship:
1) Mutualism‐ both organisms benefit from living together ☺☺‐ ex. bacteria in digestive tract of cattle
• bacteria benefit by having food and a home• cattle benefits by being able to digest grass
4.2 What Shapes an Ecosystem?
2) Parasitism‐ one organism benefits, the other organism is harmed ☺
– ex. 1: ticks (parasite) living on other animals (host)
leech hookworm
4.2 What Shapes an Ecosystem?
2) Parasitism‐ one organism benefits, the other organism is harmed ☺
– ex. 2: wasp larvae (parasites) feed on caterpillar (host)
Organism benefits0
_
Organism is harmed
Hornworm caterpillarThe host hornworm will eventually die as its organs are consumedby wasp larvae.
Braconid waspBraconid larvae feed on their host and release themselves shortly before reachingthe pupae stage of development.
_
Parasitism+0
4.2 What Shapes an Ecosystem?
3) Commensalism‐ one organism benefits, the other organism is neither harmed nor benefits ☺
– ex. 1: epiphytes (smaller plants living on larger plants)
Spanish moss hangs on treebut does not harm the tree.
4.2 What Shapes an Ecosystem?
3) Commensalism‐ one organism benefits, the other organism is neither harmed nor benefits ☺
– ex. 2: mites living in human eyelashes
Human Our eyelashes are home to tiny mitesthat feast on oil secretions and dead skin. Without harming us, up to 20 mites may be living in one eyelash follicle.
Demodicids Eyelash mites find all they need to survive in the tiny folliclesof eyelashes. Magnified here 225 times, these creatures measure 0.4 mm in length and can be seen only with a microscope.
+
Organism benefits+
Ø
Ø Organism is not affected
Commensalism
4.2 What Shapes an Ecosystem?
Succession is the gradual, sequential replacement of plant communities in an area over time
• Two types of succession:1) Primary succession2) Secondary succession
4.2 What Shapes an Ecosystem?
Primary Succession
• occurs where life has never existed beforeex: on fresh lava flow
4.2 What Shapes an Ecosystem?
Primary Succession
1) begins with the pioneer community‐ the pioneer species are the first to colonize a habitat and change the environment so that it becomes more suitable for other species to liveex. bare rock being broken down by lichens and
mosses – beginning of soil formation
4.2 What Shapes an Ecosystem?
Primary Succession2) seral communities (intermediate communities) gradually replace pioneer communitiesex: grasses replacing lichens and mosses
shrubs replacing grasses
4.2 What Shapes an Ecosystem?
Primary Succession3) climax community gradually replaces the seralcommunities‐ the final stage of succession (most stable)‐ the community that will stay stable as long as thearea is not disturbed ex: tropical rainforest, temperate forest
4.2 What Shapes an Ecosystem?
Secondary Succession• occurs when some type of disturbance causes adisruption of the pattern of an ecosystem (fire, timberharvesting, wind, grazing and browsing)
4.2 What Shapes an Ecosystem?
Secondary Succession• damaged communities can be regenerated becausethe soil still remains • pioneer species reappear, then followed by the intermediate communities, and eventually returns to the climax community
4.2 What Shapes an Ecosystem?
Earth has six major biomes.• A biome is a major community of organisms.
4.3 Biomes
• The tundra biome is found in the far northern latitudes with long winters.– winter lasts 10 months– limited precipitation– permafrost
Barrow, Alaska
Source: National Oceanic Atmospheric Administration
4.3 Biomes
• The taiga biome is located in cooler northern climates.– boreal forest– long winters and short summers– small amount of precipitation
Source: Environment Canada
Banff, Canada
4.3 Biomes
– Deciduous trees are the dominant plant species.– The temperate rain forests have a long wet season and relatively dry summer.
• Temperate forest biomes include deciduous forests and rain forests.
– Temperate deciduous forests have hot summers and cold winters.
– Ferns and moss cover the forest floor.
4.3 Biomes
• Temperate forest biomes include deciduous forests and rain forests.– Temperate deciduous forests have hot summers and cold winters.– Deciduous trees are the dominant plant species.
Source: National Oceanic Atmospheric Administration
Burlington, Vermont
4.3 Biomes
• Desert biomes are characterized by a very arid climate.– very low amount of precipitation– four types: hot, semi-arid,
coastal, and cold
Tucson, Arizona
Source: National Oceanic Atmospheric Administration
4.3 Biomes
– Temperate grasslands are dry and warm during the summer; most precipitation falls as snow.
• Grassland biomes are where the primary plant life is grass.
– Tropical grasslands are warm through the year, with definite dry and rainy seasons.
4.3 Biomes
• Grassland biomes are where the primary plant life is grass.
Rapid City, South Dakota
Source: National Oceanic Atmospheric Administration
4.3 Biomes
• Tropical rain forest biomes produce lush forests.– warm temperature– abundant precipitation all
year
Source: World Meteorological Organization
4.3 Biomes
