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Ecology & Biodiversity. Unit 3 AP Environmental Science. Terminology. Ecology : the study of how species interact with one another & their surrounding environment. Biodiversity : the variety of the Earth’s species

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ecology biodiversity

Ecology & Biodiversity

Unit 3

AP Environmental Science

  • Ecology: the study of how species interact with one another & their surrounding environment.
  • Biodiversity: the variety of the Earth’s species
    • Functional diversity: energy flow & matter cycling needed to sustain ecosystems.
    • Genetic diversity: variety of genes within a population
    • Ecological diversity: variety of ecosystems on Earth
    • Species diversity: number & abundance of species in communities
how do organisms get energy
How do Organisms get Energy?

Photosynthesis: Converting light energy (from the sun) into usable chemical energy


how do organisms get energy1
How do Organisms get Energy?

Cellular Respiration: The process of breaking down simple sugars to release energy.

Producers & Consumers

Aerobic: oxygen present

Anaerobic: oxygen not present (fermentation)

how do organisms get energy2
How do Organisms get Energy?

The Sun is the ultimate source of energy on Earth

how do organisms get energy3
How do Organisms get Energy?
  • Chemosynthesis: process in which organisms convert inorganic chemicals (H2S or H2) into usable energy.
    • Deep-sea hydrothermal vents
    • Hot springs
    • Intensely salty lakes
    • Deep in rock formations
    • Deep-sea (w/o thermal vents)
levels of organization in an ecosystem
Levels of Organization in an Ecosystem

Species: all organisms of the same kind that are genetically similar to breed in nature and produce fertile, live offspring.

Population: all members of the same species living in a given area at the same time.

Community: all populations interacting together in a given area at the same time.

Ecosystem: a community and its environment (abiotic – nonliving factors) (biotic – living factors)

transferring energy in an ecosystem
Transferring Energy in an Ecosystem
  • Producers: organisms the photosynthesize
  • Productivity: amount of biomass produced in a given period of time.
    • Biomass: biological material
  • Food Chain: a linked feeding series
  • Food Web: a diagram of interconnected

food chains

transferring energy in an ecosystem1
Transferring Energy in an Ecosystem
  • Trophic Level: an organism’s feeding status in an ecosystem
    • Producer
    • Primary Consumer (Herbivore)
    • Secondary Consumer (Carnivore, Omnivore)
    • Tertiary Consumer (Carnivore, Omnivore)
    • Quaternary Consumer (Carnivore, Omnivore)
  • Consumer: eat producers for energy
    • Herbivore: eats only plants
    • Carnivores: eat flesh (meat) only
    • Omnivore: eats both plants and animals
transferring energy in an ecosystem2
Transferring Energy in an Ecosystem
  • Other Consumers:
    • Scavengers: eat and clean up dead carcasses of larger animals.
      • Crows, jackals, vultures
    • Detritivores: eat litter, debris, dung
      • Ants, beetles
    • Decomposers: complete final breakdown and recycling of organic materials.
      • Fungi, bacteria
transferring energy in an ecosystem3
Transferring Energy in an Ecosystem

Consumers that feed at all levels:

Scavengers & Decomposers

transferring energy in an ecosystem4
Transferring Energy in an Ecosystem

ONLY 10% of Energy moves to the next trophic level!

biogeochemical cycles
Biogeochemical Cycles

Hydrologic Cycle (aka water cycle):

biogeochemical cycles1
Biogeochemical Cycles
  • Carbon Cycle:
    • Needed to make

organic molecules

    • Bonds with carbon

contained “stored”


biogeochemical cycles2
Biogeochemical Cycles
  • Nitrogen Cycle:
    • An element needed in making

organic molecules

    • Assimilation: the taking in of

nitrogen by plants

    • Nitrogen fixation: bacteria

combine N with H to form

NH3 (ammonia)

    • Nitrification: bacteria turn

ammonia into nitrates (NO3)

    • Denitrification: bacteria

convert NO3 into N2

biogeochemical cycles3
Biogeochemical Cycles
  • Phosphorous Cycle:
    • More phosphorous =

more lush plant growth

but also more water


    • Phosphorous has

NO atmospheric


biogeochemical cycles4
Biogeochemical Cycles
  • Sulfur Cycle:
    • Important

for making


speciation evolution
Speciation & Evolution
  • Adaptation: acquisition of traits that allow a species to survive in its environment.
    • Acclimation – immediate response to a changing environment, but not past on genetically
    • Natural Selection –
      • organisms better suited to the environment survive 
      • offspring inherit the beneficial traits 
      • over generations, these become the traits of a population
      • Evolution brought on by an accumulation of mutations over time.
speciation limitations
Speciation & Limitations
  • Limitations to where a species can live
    • Physiological factors
      • Moisture, temperature, light, pH, or a specific nutrient
    • Competition with other species
    • Predation, parasitism, disease
    • Luck
  • An organisms design may allow it to only live within certain conditions
    • Critical Factor: the single factor in shortest supply relative to demand.
      • Saguaro Cactus – so sensitive to freezing temperatures that one freezing night below O for 12 hours or more stunts its growth, and it can no longer develop.
speciation limitations1
Speciation & Limitations

Tolerance Limits: each factor has a minimum and maximum level in beyond which a species would not be able to survive or reproduce.

speciation ecological niches
Speciation & Ecological Niches
  • Habitat: place or environmental conditions in which a species lives.
  • Ecological Niche: role played by the species in their community or a total set of environmental factors that determine the distribution of a species.
    • Generalist: has a wide range of tolerances for many factors
      • Brown rat
    • Specialist: have exacting habitat requirements, lower reproductive rates, and care for their young.
      • Giant Panda
    • Endemic: highly specialized to their habitat and do not exist anywhere else
      • Flora & Fauna on the Galapagos Islands
speciation ecological niches1
Speciation & Ecological Niches
  • Competition: fighting for the same resources
    • Competitive Exclusion Principle: no two species can occupy the same ecological niche for a long period of time.
      • The more efficient will survive, while the less will either find another habitat, die out, or experience a change in its behavior or physiology.
    • Resource Partitioning: several species can use different parts of the same resource and coexist.
speciation diversity
Speciation & Diversity
  • Speciation: the development of a new species
    • Gradualism
    • Punctuated Equilibrium
speciation diversity1
Speciation & Diversity
  • How speciation occurs:
    • Geographic Isolation (Allopatric Speciation): species arise in separate geographic regions due to physical barriers causing reproductive isolation.
    • Behavioral Isolation (Sympatric Speciation):behaviors that cause reproductive isolation even though the organisms live in the same place.
species interactions
Species Interactions
  • Competition:
    • Intraspecific Competition: competition within a species
      • Reducing competition:
        • Dispersal of young
        • Strong territoriality
        • Resource partitioning between generations
          • Young/adults feed differently
    • Interspecific Competition: competition among different species
    • The species living in the optimal range of their tolerance limits will have an advantage over a species living outside of their optimal range.
species interactions1
Species Interactions
  • Predator: any organism that feeds directly on any other living organism.
    • Predators: herbivores, carnivores, omnivores
    • NOT Predators: scavengers, detritivores, decomposers
  • Predator-mediated Competition: a superior competitor in a habitat will build up a larger population than its competing species; predators notice and increase hunting pressure of the superior species, reducing the superiors abundance, allowing the weaker species to increase its numbers.
species interactions2
Species Interactions
  • Predator-Prey Relationships can lead to co-evolution.
    • Co-evolution: when two interacting species evolve with each other because of their interactions.
      • Cheetah & Gazelle
species interactions3
Species Interactions
  • Mimicry
    • Batesian mimicry: harmless species look like poisonous or distasteful ones to scare of predators.
    • Mullerian mimicry: two harmful species look alike and predators learn to avoid both.
species interactions4
Species Interactions
  • Camouflage: Use of color, patterns, and form to blend in to the environment.
    • Helps prey hide from predators BUT
    • Also helps predators hide while lying in wait for their prey
species interactions5
Species Interactions

Mutualism: relationship between two organisms benefit each other.

Commensalism: one organism benefits, but the other organism in not affected.

Parasitism: one organism benefits and the other organism is harmed.

major species roles in an ecosystem
Major Species Roles in an Ecosystem
  • Native species:
    • A species that normally lives and thrives in a particular ecosystem.
  • Nonnative (Invasive) Species:
    • A species that migrates to or is introduced (purposely or accidentally) into an ecosystem.
major species roles in an ecosystem1
Major Species Roles in an Ecosystem
  • Indicator species:
    • Species that provide early warnings of damage to a community or an ecosystem.
  • Foundation species:
    • species that plays a major role in shaping their communities by creating and enhancing their habitats in ways that benefit other species.
major species roles in ecosystems
Major Species Roles in Ecosystems
  • Keystone species:
    • A species who has a large influential impact on its community or ecosystem than its abundance would suggest.
  • Difference between a foundation species & keystone species
    • Foundation species help create habitats & ecosystems
    • Keystone species can do this, but also play and active role in maintaining an ecosystem and keep it functioning.
properties of ecosystems
Properties of Ecosystems
  • Primary Productivity: Rate of biomass production (conversion of solar energy to chemical energy)
    • Energy left after respiration = net primary production
properties of ecosystems1
Properties of Ecosystems
  • Abundance: total number of organisms in a biological community.
  • Diversity: measure of the number of different species, ecological niches, or genetic variation present.
  • Abundance is usually inversely related to diversity
    • Diversity up, Abundance down
    • Diversity down, Abundance up
  • Generally diversity decreases but abundance within a species increases from the equator toward the poles.
properties of ecosystems2
Properties of Ecosystems
  • Ecological structure: patters of spatial distribution of individuals and populations within a community
    • Random
      • Live where resources are available
    • Uniform
      • Physical environment
      • Biological competition
    • Clustered
      • Protection
      • Mutual assistance
      • Reproduction
      • Access to resources
properties of ecosystems3
Properties of Ecosystems
  • Complexity: number of species at each trophic level and the number of tropic levels in a community.
  • Stability or Resiliency:
    • Constancy: lack of fluctuations in composition or function
    • Inertia: resistance to disturbances
    • Renewal: ability to repair damage after a disturbance
  • The more complex and interconnected an ecosystem, the more stable and resilient it is.
    • Many species in one trophic level, one can replace another
    • However, removal of a keystone species can greatly affect any system
properties of ecosystems4
Properties of Ecosystems
  • Edge Effects: change is species composition, physical environment or other ecologic properties between ecosystems
    • Sometimes sharp and distinct
      • Woodlands  grasslands
    • Gradual integration to from one to another
  • Ecotones: boundaries between adjacent communities
    • Sharply divided: closed community
    • Indistinctly divided: open communities
changing communities
Changing Communities
  • Ecological succession: changes in an community as organisms occupy a site and the change the environmental conditions.
    • Primary Succession: land that is bare of soil and colonized by organisms where none lived before
      • Sandbar, mudslide, rockface, volcanic flow
    • Secondary Succession: existing community is disturbed and a new one develops from the disturbance
      • Wild fire, clear cut forests, urbanization
    • Successions occur by:
      • Modifying soil
      • Light levels
      • Food supplies
      • microclimate
changing communities1
Changing Communities
  • Terrestrial Primary Succession
    • Primary species: first colonists
      • Microbes, mosses, lichens (live off few resources)
    • When primary species die = organic matter = soil production
    • Seeds lodge in soil and grow
    • Succession progresses  more diversity
changing communities2
Changing Communities
  • Disturbances: anything that disrupts established patterns of species diversity and abundance, community structure, or community properties
    • Landslides, mudslides, hailstorms, tidal waves, tornadoes, volcanoes (natural)
    • Animal disturbances
      • elephants ripping down small trees
      • Agriculture, forestry, urbanization, dams, pipelines
  • Disturbance-adapted species: species that recover quickly from a disturbance
  • Biological extinction: when a species can no longer be found anywhere on Earth
    • Forever
    • Irreversible
    • Weaken or even break an ecosystem
      • Can lead to secondary extinctions
  • Background extinction rate: the natural, low rate extinction of species
  • Extinction rate: percentage or number of species that go extinct within a determined period of time.
mass extinctions
Mass Extinctions
  • The extinction of many species in a relatively short (geologically) period of time.
    • Fossil Records show that Earth has experienced at least 3 mass extinctions, where 50-95% of all species went extinct
      • Biodiversity has always returned to equal or higher levels, but required millions of years.
      • Causes are not well understood, but theories lead to environmental changes.
human activities leading to extinction
Human Activities Leading to Extinction
  • Underlying Causes
    • Population growth
    • Rising resource use
    • Undervaluing natural capital
    • Poverty
  • Direct Causes
    • Habitat loss
    • Habitat degradation & fragmentation
    • Introduction of nonnative (invasive) species
    • Pollution
    • Climate change
    • Overfishing
    • Hunting & poaching
    • Sale of exotic pets/plants
    • Predator/pest control

Habitat destruction

Invasive species

Population Growth & Increasing resource use


Climate Change


endangered threatened species
Endangered & Threatened Species
  • Endangered: so few of a species are living that they could soon become extinct
    • Sumatran tiger: < 60
    • Mexican Gray Wolf: ~ 60
    • California Condor: 172
    • Whooping Crane: 210

Threatened: still has enough living members to survive short term but could easily become an endangered species.

characteristics that can lead to extinction
Characteristics that can lead to Extinction
  • Low reproductive rate:
    • Blue whale, giant panda, rhino
  • Specialized niche
    • Blue whale, giant panda
  • Narrow distribution
    • Elephant seal
  • Fixed migratory patterns
    • Blue whale, whooping crane, sea turtle
  • Rare
    • African violet, some orchids
  • Commercially valuable
    • Snow leopard, tiger, elephant, rhino, rare plants & birds
  • Large territories
    • California condor, grizzly bear, Florida panther
why does extinction matter
Why does extinction matter?
  • Rates are rising rapidly
    • 1000 times higher than the background extinction rate.
    • If rate is 1% a year, ¼ to ½ of the Earth’s current species can be extinct in a century.
  • 1. species are a vital part of the Earth’s life support system.
    • Provide resources & services
  • 2. species contribute to economic services
    • Crops, medicine, etc.
  • 3. 5-10 million years to regain biodiversity after mass extinction

Biomagnification: Levels of toxins are concentrated up the food chain

protecting species
Protecting Species
  • Convention on International Trade in Endangered Species (CITES) 1975
    • Signed by 175 countries
    • Bans hunting, capturing, & selling threatened & endangered species
    • Restricts international trade of species that are at risk of becoming threatened.
  • Limited effectiveness because:
    • Enforcement varies from country to country
    • Only small fines are levied
    • Member countries can exempt themselves from protecting any listed species
    • Highly profitable & illegal trading still occurs in nonmember countries
protecting species1
Protecting Species
  • Convention on Biological Diversity
    • Signed by 191 countries
    • As of 2010, US not a member
    • Commits participating governments to reduce the global rate of biodiversity loss & to equitable sharing of benefits of the world’s genetics resources
      • Prevention & control of harmful invasive species
  • Important because:
    • Focuses on ecosystems as a whole, not just individual species
    • Links biodiversity protection to the traditional rights of indigenous people
  • Slow progress because key countries have not ratified the agreement
    • Has no severe penalties
protecting species2
Protecting Species
  • US Endangered Species Act of 1973
    • Designed to protect endangered species in the US and around the world
    • Most far reaching environmental law, controversial
    • NMFS (National Marine Fisheries Service): decides marine species
    • USFWS (US Fish & Wildlife Service): decides on terrestrial species
  • Other methods:
    • Wildlife refuges
    • Gene banks
    • Botanical gardens
    • Wildlife farms
    • Zoos
    • Aquariums