Topic 6: Ecology

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Topic 6 Ecology

• I. Parts of an EcosystemII. Population Dynamics

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What is it?
ECOLOGY

• Study of how organisms INTERACT with living and
  non-living things

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What will we be looking at?

• Parts of an ecosystem
• Things that affect popn size
• Roles and relationships in an ecosystem
• Energy flow in an ecosystem
• Importance of biodiversity
• Succession
• Human impacts on the environment

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Ecosystem describes any portion of the
environment (ie. Decaying log, a pond, fish
tank, field of corn)
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The environment is every living and nonliving
thing that surrounds an organism
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Ecosystems Brainpop (139))
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What makes up an ecosystem?
Abiotic Factors
Biotic Factors
ECOSYSTEM
ECOSYSTEM
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• 1. BIOTIC FACTORS
• Bio means living
• LIVING things in an ecosystem
• ie.Plants, animals,
• bacteria
• Can you list the living things that could live in
  this ecosystem?
• Frogs, insects, fish, hawks, grasses, bacteria,
  amoeba etc..

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• 2. ABIOTIC FACTORS
• When you put a in front of a word it negates it
• Means NON-LIVING factors
• Can you list some non-living factors that affect
  the pond ecosystem?
• WATER, LIGHT, TEMP, acidity, oxygen and nitrogen
  levels

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Ecological Levels of the Organization of Life
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Collectively all of the Earths ecosystems make
up the biosphere
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The specific environment in which organisms live
is their habitat
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Ecosystem - populations in a community and the
abiotic factors with which they interact (ex.
Biomes)
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All the different populations are combined to
form a community
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All the organisms of a species that live in the
same area, produce fertile offspring, and compete
with each other for resources (food, mates,
shelter, etc.) make up a population
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• Organism - any unicellular or multicellular form
  exhibiting all of the characteristics of life, an
  individual.
• The lowest level of organization

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Ecological Levels of the Organization of Life

• BIOSPHERE
• HABITAT (BIOME)
• ECOSYSTEM
• COMMUNITY
• POPULATION
• ORGANISM

Decreasing amount of biotic and abiotic factors
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Population Growth Brain Pop Video (227)
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What affects population sizes in an ecosystem?

• COMPETITION!
• Struggle for resources among organisms
• If no competition, populations would grow
  INFINITELY (no limit!)
• Competition maintains FINITE (limited) popn
  sizes
• Finite populations limited by LIMITING FACTORS
• CAN BE ABIOTIC OR BIOTIC

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Lets look.Comparing Finite and Infinite
Populations
INFINTITE GROWTH
FINITE GROWTH
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What affects population sizes in an ecosystem?

• A) ABIOTIC LIMITING FACTORS
• Amount and intensity of sunlight
• Amount of water
• Amount of dissolved oxygen (lakes, rivers, etc)
• Acid level
• Temperature range
• Minerals available

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What affects population sizes in an ecosystem?

• B) BIOTIC LIMITING FACTORS
• Predator/Prey relationships
• Predators limit prey population sizes by eating
  them
• Prey limit predator population sizes by
  dying/being killed
• If too many killed, predators starve
• Adapting (survival of the best adapted)

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Lets take a look. Effects of Predator/Prey
Relationship
As you can see, AS PREY POPULATION DECREASES, THE
PREDATORS POPULATION DECREASES (Direct
relationship)
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What do we call it when a species reaches its
limit?

• EVERY population in an ecosystem has a CARRYING
  CAPACITY (K)
• THE OF ORGANISMS OF A SINGLE SPECIES AN
  ECOSYSTEM CAN SUPPORT
• Determined by BIOTIC and ABIOTIC factors
• EX a fox population is affected by how much it
  has to eat (biotic) and also temperature
  (abiotic)
• Once K is reached, population will remain stable
  unless major changes in biotic and abiotic factors

Carrying Capacity (K) of a Stable Population
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Part 2 POPULATION INTERACTIONS

• How organisms interact in an ecosystem!
• What role are you up for?

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Competitive Exclusion Principle

• If two different species compete for the same
  food source or reproductive sites, one species
  may be eliminated.
• This establishes one species per niche in a
  community.

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A. What does it mean to have a role in an
ecosystem?

• NICHE
• THE ROLE (NOT SPACE!!!!!) AN ORGANISM PLAYS IN
  ITS ECOSYSTEM
• ONLY ONE SPECIES CAN OCCUPY A NICHE AT A TIME
• LEADS TO COMPETITION IF MORE THAN ONE SPECIES
  WANTS ROLE
• SIMILAR SPECIES CAN COEXIST AS LONG AS THEY HAVE
  DIFFERENT NICHES!
• EX p102 in RB WARBLERS

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HOW CAN I REMEMBER THAT NICHE MEANS ROLE AND
NOT SPACE?

• THINK OF A PLAY!
• EVERY ROLE NEEDS TO BE FILLED IN ORDER FOR THE
  PLAY TO WORK!
• IF MORE THAN TWO FOLKS (SPECIES) WANT A ROLE,
  THERE IS COMPETITION AND THE BEST WINS!

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What are the relationships in an ecosystem?

• Food chain Food web
• (1 path of energy) (all possible energy
  paths)

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B. What are the relationships in an ecosystem?

• 1. FOOD CHAINS
• Illustrate NUTRITIONAL RELATIONSHIPS between
  predators and prey
• 1 path of energy
• Specific organisms are included
• Lets take a look!

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FOOD CHAINS
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Feeding Relationships

• A. Autotrophs (Producers)
• Make own food (grass)
• B. Heterotrophs (Consumers)
• Herbivores Eat plants (grasshopper)
• Carnivores Eat animals (snake)
• Omnivores Eat plants and animals (humans)
• Scavengers Eat dead things lifes clean-up
  crew! (vultures)
• Decomposers lifes recyclers (bacteria and fungi)

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• 2. SYMBIOTIC RELATIONSHIPS
• When organisms live in REALLY close quarters
• Parasitism Live off other orgs but dont kill
  them (some worms, ticks, fleas)
• Mutualism Orgs that both benefit (Clownfish and
  sea anemone)
• Commensalism One org benefits the other -
  neither harmed or benefitted (Whale and barnacles)

PARASITISM MUTALISM
COMMENSALISM
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• 3. FOOD WEBS
• All food chains in an ecosystem are illustrated
  in a food web
• INVOLVES all possible energy paths

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Food Webs are diagrams that show more complex
feeding relationships
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A simplified food web at a pond
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Lets talk energy! The fuel of life!

• Ask yourself Where does our ultimate source of
  energy come from?
• The sun of course!
• Ask yourself Which orgs can harness suns
  energy and make food?
• Plants of course!
• Ask yourself What happens to the plants energy
  when a herbivore eats it?
• Ask yourself What happens to the herbivores
  energy when a carnivore eats it?
• Ask yourself What happens to the carnivores
  energy when another carnivore eats it?

Decreases
Decreases
Decreases
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1. What happens to ENERGY in an ecosystem?

• Every organism uses energy to carry out life
  processes
• If an organism is eaten, it will give less energy
  to the predator
• THEREFORE, ENERGY DECREASES AS YOU MOVE UP A FOOD
  CHAIN!

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• WE USE AN ENERGY PYRAMID TO SHOW THIS
• see fig 6-7 and 6-8 on page 107 in your review
  book!

Carnivores - BIRD
Herbivores - CATERPILLAR
Producers(Autotrophs) OAK TREE
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As energy is transferred, much of it is lost to
the environmentLets watch http//www.brainpop
.com/science/energy/energypyramid
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D. RECYCLING NUTRIENTS

• DECOMPOSERS extract what little nutrients are
  left
• They return raw materials (nitrogen) back to soil
• Other orgs continually recycling CARBON DIOXIDE,
  OXYGEN, AND NITROGEN
• ENERGY IS NEVER RECYCLED!
• involves the processes of RESPIRATION and
  PHOTOSYNTHESIS.

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Lets look at pg 108 in RB RECYCLING OF
MATERIALS IN ECOSYSTEMS

• Lets Watch brain pop carbon CYCLE VIDEO (232)