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Ecology
Study of interactions among organisms…. & between organisms with their environmental factors3-The Biosphere
Biosphere• The portion of the Earth that supports life
• Composed of two parts:
1. Biotic factors – the living organisms that inhabit an environment
• All organisms depend on others directly or indirectly for food, shelter, reproduction, or protection
2. Abiotic factors – the nonliving parts of an organisms environment
• Air currents, temperature, light, moisture
• Have effect on living things and often determine which species can survive in an area
Levels of organization in an organism
• Chemicals make up cells…
• Which make tissues…
• Organs…
• Systems…
• And finally, the individual organism
Levels of organization in ecology
• In Ecology, we begin with the individual and move through the levels to the planet, Earth
Species
• Group of organisms with similar characteristics
• Able to breed and produce fertile VIABLE offspring
Species Hybrid
Populations
• Group of individuals (of the same species) that live in the same area
• Example?
• All the fire ants in a pasture
Community
• Groups of different populations that live together
• Examples?
• All the ants, birds, grass, cows, etc in
a pasture
Ecosystem
• Collection of all organisms (biotic) that live in a particular area, together with their non-living (abiotic) parts of an environment
• Examples of abiotic factors??
• Climate, soil type, amount of rainfall, etc
Southern Pine Ecosystem
Fort Bragg, North Carolina
Community Ecology
• Habitat – a specific place where an organism lives out his life
• Niche – the role an organism
plays in the environment
Symbiotic Relationships – two organisms living
in close association with one another
1. Competition (-/-)• compete for limited resource
• Food, mate, territory
2. Predation (+/-) – Hunt and kill your prey
3. Parasitism (+/-)
4. Mutualism (+/+)• lichens (algae & fungus)
5. Commensalism (+/0)• barnacles attached
to whale
Symbiosis – two organisms living in close association with one another
Mutualism
The act of two organisms utilizing one another. Both thrive and help each other.
Commensalism
The act of one organism utilizing another living organism. One thrives and the other is neither harmed nor helped
Parasitism
The act of one organism feeding upon another living organism. The parasite thrives to the host’s detrimentand the host is harmed.
commensalism
predation competition
mutualism
+/0
+/+
+/-
-/-
Symbiotic Relationships
Herbivores(a.k.a. primary
consumers)
feed directly on
producers
Types of Consumers:
Carnivores (a.k.a.
secondary consumers)
feed on other animals
Types of Consumers:
Omnivores • feed on both plants and
animals
• can be either primary or secondary consumers, depending on food chain
Types of Consumers:
Scavenger
• An animal or other organism that feeds on
dead organic matter
• Decomposers/Saprophyte/Detritivores
• feed on (and recycle) dead or decaying matter
• completing the chain, by returning nutrients needed by producers to the environment
Scavengers eat dead
things but do not recycle
Decomposers feed on dead
things AND recycle them
Types of Consumers:
Energy flow through the biosphere
• Autotrophs (producers) • organisms that make their own food
• Heterotrophs (consumers)• Rely on other organisms for their food supply
AUTOTROPHS
Water + CO2 Sugar + O2
HETEROTROPHS
Sugar + O2 water + CO2
What’s the ultimate source of energy for all life?
Food chain
• Series of steps in which organisms transfer energy by eating and being eaten
• Arrow always points the direction of energy flow…..to the consumer
Food Chain
• The pathway of energy that DECREASES as it passes through the trophic (feeding) levels
• Trophic level of an organism is the position it occupies in a food chain
Food web
• Network of complex interactions, linking all of the food chains together
• Show ALL the possible feeding relationships
• Many connections throughout ecosystem
Ecological Pyramids• Energy
Pyramid
• BiomassPyramid
• Numbers Pyramid
Hawk-eye Question: Why are all three shaped as a pyramid?
Energy
Lost as
Heat
What is the relationship between the numbers of
producers and Consumers?
How does this relate to the energy flow through the
ecosystem?
pyramid of numbers
So fewer and fewer
organisms can be
supported at each level
ONLY 10% of energy is passed on to next levelEnergy Pyramid
Biogeochemical cycles:
• Water (hydrologic) cycle
• Driven by solar energy
• Recycles water, which is primary component of all life
• Phosphorus Cycle • driven by decomposing
bacteria & fungi
• phosphorus is an important component of ATP, Nucleic acids, & phospholipids
Carbon Cycle• The Carbon Cycle is driven
mainly by TWO processes:
• Photosynthesis the process by which producers convert sunlight into a useable form of energy
• Cellular Respiration overall process by which the body gets and uses oxygen and gets rid of carbon dioxide
CO2 in
Atmosphere
CO2 in Ocean
Nitrogen Cycle• driven by decomposition by nitrifying bacteria and fungi
• atmospheric nitrogen must be converted to a usable form that plants can use NITRATE
N2 in Atmosphere
NH3
NO3–
and NO2–
What form of nitrogen can plants use?
• Atmospheric Nitrogen… N2?
• Proteins?
• Amino Acids?
• Ammonia… NH3?
• Ammonium… NH4?
• Nitrite… NO2?
• Nitrate … NO3?
Day 2
Ecological Succession
IV. Ecological Succession
• transition in species composition over time • SLOW process, can take years or decades
• usually occurs after a disturbance
• Two types: Primary and Secondary
Mt. St. Helens
1. Primary Succession
• Takes place over land where there are NO living organisms.
• Ex. Bare rock, volcano created new island
Succession of Species
lichens & mosses grasses
treesbushes & small trees
pioneer species
climax forest
compete well in high sunlight
more shade tolerant species
shade tolerant species
stable community
2. Secondary Succession
• Existing community cleared, but base soil is still intact• Ex. Forest fire, harvesting, hurricane
burning releases
nutrients formerly
locked up in the
tissues of tree
the disturbance
starts the process
of succession
over again
Mt St Helens Vid Clip
Bastrop Fire
Bastrop Fire Vid of Bastrop Sept 2015
IIV. Species diversity• Greater diversity = greater stability
• Greater biodiversity offers:
more food resources
more habitats
more resilience in face of environmental change
Populations• members of the same species that reside in the same
area
Characteristics of populations
a. Geographic distribution:
Where do they live?
b. Density:
How many are found in a given unit of area
c. Growth rate:
How quickly do they grow?
Daisy population
Factors affecting population growth?
1. Birth rate:
number of offspring per time period
2. Death rate:
number of deaths per time period
3. Migration rate
movement in and out of populations in a period of time
• Immigration: in• Emigration: out
Exponential growth
• Occurs when individuals in a population reproduce at a constant rate
• Only under ideal conditions
Exponential growth activity
• White flies have a 21 day life span
• During their life span the female will lay approx. 120 eggs
• Calculate the exponential growth of one pair of flies for 6 generations.
• For this experiment we will assume that no death occurs
Logistic growth• Occurs when a population’s growth rate slows or stops,
following a period of exponential (geometric) growth
• Carrying capacity: largest number
that a given environment
can support
Click image to play video.
Limiting factors• cause population growth to stop
• Density-dependent factors depend upon population size:
• Competition
• Predation
• Parasitism
• Disease
Competition• Occurs when 2 species occupies the same niche &
habitat
• What are some things they compete for?
Competition
• Using this 1990 census map of US population densities, what can one deduce at resource competition between the different parts of the country?
How can competition explain
population size in nonhuman
species?
Predation
• Predator: one that consumes or exploits a particular species for self gain
• Prey: one that is consumed or exploited
• What would you expect to happen to prey populations if the predator numbers increased or if predator numbers decreased?
Figure 5-7 Wolf and Moose Populations on Isle Royale
60
50
40
30
20
10
01955 1960 1965 1970 1975 1980 1985 1990 1995
2000
1600
1200
800
400
0
2400
Moose Wolves
Describe the relationship between the wolf and
moose populations shown in the graph.
Predator-Prey relationships
Parasitism and Disease
• Both deplete the host organism of vital minerals and nutrients to sustain life.
• Death of the organism results in the decline of population size.
Heart worms (roundworms) as
exposed by a veterinarian
Density-independent factors
• Limiting factors on population size,
regardless of the
number of individuals
in the population• Weather
• Natural disaster
• Seasonal cycles
• Human activities (habitat destruction)
Corals that have died from weather
changes, leading to increased
water temperature and pollution.
Day 3
Historical Human Population Growth
Agriculturebegins
Plowingand irrigation
Bubonicplague
IndustrialRevolutionbegins
It took 500,000 years to reach 1 billion
& less than 200 years to reach 5 billion.
What might be some reasons why?
What’s the carrying capacity for the human
population?
What if it’s right here? ---------------------------
But, what if it’s right here? ---------------------------
(We do know it lowers when pollution occurs)
Age structure diagrams (population profiles):
graphs showing numbers of people in different age groups in the population
U.S. Population Rwandan PopulationMales MalesFemales Females
What conclusions can be drawn from these graphs?
Human activities that affect the biosphere
• Hunting& Gathering
• Agriculture
• Industry
• Urban development• Austin Smart Growth Initiative
Types of resourcesNonrenewable resources:
• unable to be replenished through natural means
• Ex: fossil fuels, natural gas
Renewable resources:
• able to be replenished but is not unlimited
• Ex: freshwater
Sustainable development
• A way to use natural resources without causing long term environmental problems
• This plan takes into consideration environmental, economic, and community demands
Problems land resources face
Desertification
• the process of overusing land and drought leading to the formation of arid, desert lands that cannot sustain agriculture
Soil erosion • loss of topsoil layer from over farming (plowing) lands
Deforestation• The process of cutting down (logging) forests for lumber and land.
• Leads to severe erosion during heavy rains.
• Which can lead to permanent changes to local soils and microclimates.
Overfishing• Harvesting fish faster than they can be replaced by
reproduction.
• What happens to aquatic food webs if overfishing continues to occur?
Aquaculture• raising water animals for
human use
• Pictured to the right are tilapia fish farms in Australia that then export the fish to markets.
Air pollution• Combustion of carbon
fuels released nitrogen and sulfur that combine with water to form acid rain.
• Pollutant:
• any harmful substance that enters the biosphere from land, air, or water
Acid rain
Why should we preserve biodiversity?
Biodiversity:
• sum total of genetically based variety of all organisms in the biosphere• Ecosystem diversity• Species
diversity
Why should we preserve biodiversity?
• Biodiversity is one of Earth’s greatest natural resources.
• Species of many kinds have provided us with foods, industrial products, and medicines – including painkillers, antibiotics, heart drugs, antidepressants and anticancer drugs.
Threats to species biodiversity
• Human activity can reduce biodiversity by altering habitats, hunting species to extinction, introducing toxic compounds into food webs, and introducing foreign species to new environments.
Threats to species biodiversity
• Endangered: species that is declining in population size
• Extinction: species that disappears from all or part of its range
Endangered status:
Ailuropoda melanoleuca
Dodo Bird
• The dodo has been extinct since the mid-to-late 17th century.
• Its extinction occurred during recorded human history and was directly attributable to human activity
Habitat fragmentation• When land is developed through or around
ecosystems, the species residing within are impacted in what way?
Central Park in New
York City is a perfect
example of habitat
fragmentation.
DDT
• First synthesized in 1874, DDT's insecticidal properties were not discovered until 1939, and it was used with great success in the second half of World War II to control malaria and typhus among civilians and troops.
• After the war, DDT was used as an agricultural insecticide, and soon its production and use skyrocketed
• DDT was banned in most countries in 1972
Biomagnification / BioAccumulation :
• Increasing the concentration of harmful materials up the food chain
Introduced species• Humans transport animal and plant species from one
part of the world to another.
• Many of these species can become invasive. They reproduce rapidly and lack parasites and predators that helped control their populations “back home.”
Nutrias are native
to South America
but have become
pests in coastal US
cities.
Water Hyacinth
Hydrilla
Kudzu
Fire Ants
Conserving Biodiversity
• To conserve biodiversity and multi faceted approach is best:
• Protection of species
• Protection of habitat
• Protection of biodiversity
Conserving Biodiversity Challenges
• Balancing :• Public need and economics
• Public policy
• Conservation
Charting a Course for the Future• Researchers are gathering data to monitor and
evaluate the effects of human activities on important systems in the biosphere.
• Issues:
• Ozone depletion
• CO2 emissions
• Global warming
• Alternative fuels
• Alternative food sources
Ozone depletion
• Ozone: layer of concentrated gas that protects the Earth from harmful UV rays
• O3
• 1970s, scientists found a gap in the ozone layer near Antarctica.
NASA image
Global warming
• Compounding the ozone depletion was the buildup of CFCs (chlorofluorocarbons) from aerosols and AC units with Freon.
• CFCs trap heat, leading to a rise in the global temperature.
Ozone
Click on image to play video.
Value of a Healthy Biosphere
• More complex and diverse ecosystems are the more stable they are.
• Complexity + Diversity = Stability
• All ecosystems play a role in the health of the biosphere.