EcologyChapters 34, 35, and 36
Ch 34: The BiosphereEcology is the study of the interactions of
organisms with their environment.
Levels of Organization
Ecologists study environmental interactions at several levels
From MOST complex to LEAST complex:
BiosphereEcosystemCommunityPopulationOrganism
1. BiosphereThe biosphere is the global ecosystem, the sum
of all the planet’s ecosystems. It is the MOST COMPLEX level of organization in ecology.
2. EcosystemThe next level of
organization is the ecosystem level (living and non-living components in an area).
Biotic vs. AbioticAn ecosystem includes all of the living and
non-living components in a certain area.Biotic components are living things like plants
and animals.Abiotic components are the non-living
components, such as temperature, energy, gases, water, nutrients, chemicals, rocks, and soil.
3. CommunityNext is the
community level, which is all of the organisms of different species that live in an area.
HabitatsA habitat is an environmental area in which
organisms live.Habitats include communities of organismsAbiotic factors also make up habitats (rivers, lakes,
temperature, oxygen)
4. PopulationThe next level is
population, an interbreeding group of individuals belonging to the same species and living in a particular geographic area.
5. OrganismThe lowest level of organization is the organism:
an individual living thing, such as a plant, animal, bacteria, fungus, etc.
BiomesA biome is a specific ecosystem, largely
determined by climate, vegetation, and the organisms that live there.
Aquatic BiomesSaltwater oceans cover 75% of the planet’s
surface.
Freshwater biomes include: lakes, ponds, rivers, streams, and wetlands.
Terrestrial Biomes (8)Terrestrial biomes are characterized by weather,
plants, and animals living in a certain area.
1. Tropical ForestsOccur in equatorial areas where the
temperature is warm and days are 11-12 hours long year-round.
They are one of the most complex biomes with a huge diversity of species.
2. SavannasDominated by grasses and scattered trees.
3. DesertsThe driest of all biomes, with low and
unpredictable rainfall, high temperatures, and dry air.
4. Chaparral = San DiegoRegions with dense,
spiny shrubs with tough, evergreen leaves.
Mild rainy winters and hot dry summers.
5. Temperate GrasslandsGrassy areas with few trees and long, cold
winters (Chicago)
6. Temperate Deciduous Forests
Forests with deciduous trees, cold winters and hot summers.
7. Coniferous ForestsCharacterized by
cone-bearing evergreen trees.
Also called the taiga.
The largest biome on earth.
8. The TundraBetween the taiga and permanently frozen polar
regions.
Treeless, but has permafrost: permanently frozen subsoil.
Biomes Videohttp://www.encyclopedia.com/video/WZGCZY47Y
S0-biomes-of-world.aspx
Biodiversity
Chapter 35: PopulationsPopulation Ecology studies the changes in
population size and the factors that regulate populations over time.
A population is a group of individuals of the same species that occupy the same general area.
Dispersion PatternsThe dispersion pattern of a population refers to
the way individuals are spaced within their area.Clumped: individuals live in small groups or
patches throughout the area. This is the most common pattern in nature.
Uniform: even pattern dispersion resulting from interactions and competitions between organisms.
Random: pattern less, unpredictable dispersion of organisms.
Dispersion Patterns
Random Clumped Uniform
Models of Population Growth
Exponential Growth gives an idealized picture of unregulated growth of a population.
It is an unrealistic, J-shaped curve
Exponential GrowthGrowth of a population is limited by population-
limiting factors, including: Foodwaterbreeding areahuntingCompetitionbirthdeath
Logistic Growth ModelsLogistic Growth Models
show population growth when you take into account limiting factors.
They are S-shaped and more realistic.
They level off at carrying capacity: maximum population size
Survivorship CurvesThere are 3 types of survivorship curves, I, II,
and III.
r and k selectionr-selection: species in which a high reproductive
rate is the chief determinant of their lives: weeds and insects.
k-selection: species that live lives in order to produce relatively few offspring that have a good chance of survival: mammals, people, birds.
Birth and Death RatesPopulation stability is reached when there is
zero population growth, when birth rates = death rates.
The age structure of a population affects how slowly or quickly the population grows. It shows how many people of each age are living in a country.
Figure 35.9B
RAPID GROWTH
Kenya
Male Female
Percent of population Percent of population Percent of population
SLOW GROWTH
United States
Male Female
ZERO GROWTH/DECREASE
Italy
Male Female
Ages 45+
Ages 15–44
Under15
Under15
Ages 45+
Ages 15–44
Chapter 36: CommunitiesA community is an assemblage of all the
populations of organisms living close enough together for potential interaction.
The biodiversity of a community is the variety of organisms that make it up. It includes:The total number of different species in the
communityThe relative abundance of the different species
NicheA niche is the position or function of an organism in a
community.
PredationIn predation, one
species eats another.
The predator is the consumer, the one who eats.
The prey is the food, the one being eaten.
SuccessionAfter a disturbance like a fire, storm, or flood,
the ecosystem transitions from nothing to new life, in a process called succession.
Primary succession happens when there is no soil present, such as after a volcano.
Secondary succession occurs where a disturbance has left some soil, such as after a fire.
Food chains and websFood chains and food webs show the flow of
ENERGY through an ecosystem.
All energy ultimately comes from the SUN.
Energy flowEnergy starts at the producer level (plants)
Then moves up to primary consumers (herbivores)
Then to secondary consumers (carnivores)
Followed by tertiary and quaternary consumers…
Figure 36.9A
TROPHIC LEVEL
Quaternaryconsumers
Tertiaryconsumers
Carnivore Carnivore
Carnivore Carnivore
Carnivore Carnivore
Herbivore Zooplankton
Plant Phytoplankton
Secondaryconsumers
Primaryconsumers
Producers
A TERRESTRIAL FOOD CHAIN AN AQUATIC FOOD CHAIN
ProducersProducers make food. They are also autotrophs,
and typically include plants.
ConsumersConsumers eat things. They are heterotrophs.
They include:Herbivores: eat plantsCarnivores: eat animals (meat)Omnivores: eat both plants and meat
DecomposersAll food chains and webs have decomposers or
detritivores
These organisms, including bacteria, worms, rodents, insects, catfish, fungus, and vultures, eat detritus, the dead material produced at every level of a food chain.
Food WebsA food web is a
network of food chains, and is a more realistic view of energy flow.
Every food web MUST include the SUN and DECOMPOSERS
Figure 36.10
Tertiaryandsecondaryconsumers
Secondaryandprimaryconsumers
Primaryconsumers
Producers
(Plants, algae,phytoplankton)
Detritivores
(Prokaryotes, fungi,certain animals)
Wastes anddead organisms
EnergyAs you go up a level in a food chain or web, only
10% of the energy from the level below is transferred to the next level. 90% is lost as HEAT.
Because the production pyramid tapers so sharply, a field of corn or other plant crops can support many more vegetarians than meat-eaters
Figure 36.12
Secondaryconsumers
Primaryconsumers
Producers
Humanvegetarians
Corn
Humanmeat-eaters
Cattle
Corn
TROPHIC LEVEL
ReviewName a producer.
What energy level would people be at?
What energy level would a mouse be at?
Name a secondary consumer.
Why can’t food chains grow more than 5 levels high? (think about energy transfer)
Food Web Videohttp://nasa.ibiblio.org/video/NASASciFiles/NASA
WF-TheInhabitableHabitat/qt/NASAWF-FoodWeb.mov
Nutrient CyclingIn food webs, energy only moves one way, up
trophic levels.
Nutrients & materials must be recycled between organisms and abiotic reservoirs
There are 4 main abiotic reservoirs:WaterCarbonNitrogenPhosphorus
The Water CycleThe water cycle is driven by heat from the sun.
Water cycles through Precipitation (rain)Evaporation (liquid to gas)Transpiration (liquid from plant leaves turns to
gas)
Figure 36.14
Solarheat
Precipitationover the sea(283)
Net movementof water vaporby wind (36)
Flow of waterfrom land to sea(36)
Water vaporover the sea
Oceans
Evaporationfrom the sea(319)
Evaporationandtranspiration(59)
Water vaporover the land
Precipitationover the land(95)
Surface waterand groundwater
The Carbon CycleCarbon is used by photosynthesis (CO2) and
produced by cellular respiration (CO2)
Carbon is needed to make anything organic: plants, animals, people…
Carbon from the atmosphere is turned into organic compounds (like glucose) by plants that do photosynthesis!
Burning wood and fossil fuels increases CO2 in the atmosphere.
Figure 36.15
CO2 in atmosphere
Cellular respiration
Higher-levelconsumers
Primaryconsumers
Plants,algae,
cyanobacteria
Photosynthesis
Wood andfossil fuels
Detritivores(soil microbes
and others) Detritus
Decomposition
Burning
The Nitrogen CycleNitrogen exists in the atmosphere as N2, but
that cannot be used by plants and animals.
It must be converted to ammonia (NH4 ) and nitrates (NO3 )
Bacteria play major roles in this cycle
Most useable nitrogen is stored in the soil
Figure 36.16
Nitrogen (N2) in atmosphere
Amino acidsand proteins in
plants and animalsAssimilationby plants
Denitrifyingbacteria
Nitrates(NO3
–)
Nitrifyingbacteria
Detritus
Detritivores
Decomposition
Ammonium (NH4+)
Nitrogenfixation
Nitrogen-fixingbacteria in soil
Nitrogen-fixingbacteria in root
nodules of legumes
Nitrogenfixation
The Phosphorus CycleThe phosphorus cycle depends on weathering of
rock, and adding minerals to the soil.
Plants need phosphorus to grow
Consumers get phosphorus by eating plants.
Figure 36.17
Upliftingof rock
Phosphatesin solution
Weatheringof rock
Phosphatesin rock
Phosphatesin organic
compounds
Detritus
Detritivoresin soil
Phosphatesin soil
(inorganic)
Rock Precipitated(solid) phosphates
Plants
Animals
Decomposition
Runoff
To succeed on the test…1. Read the chapters.
2. Know your vocab.
3. Study the multiple choice questions in your study guide.