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Ecology - PowerPoint PPT Presentation

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Ecology. The study of interactions. Ecology: the study of interactions between organisms and their environment. Ecology. Some examples:. How the brightness of rose color affect the number of pollinators who visit the flower. How atmospheric pressure affects the growth rate of chickweed.

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The study of interactions


the study of interactions between organisms and their environment.

some examples
Some examples:
  • How the brightness of rose color affect the number of pollinators who visit the flower.
  • How atmospheric pressure affects the growth rate of chickweed.
  • The change in population size of aphids in an area where ladybugs have been introduced.
Look at the picture and namethe biotic factors.

Now name the abiotic factors

Biotic Factor:the living part of the environmentAbiotic Factor:the non-living parts of the environment
levels of organization in the environment
The lowest level in the organization is the organism.

Organism: any living thing.






Prairie Dog


Levels of Organization in the Environment
community collection of populations that interact
Community – collection of populations that interact.


Ecosystem-all the biotic and abiotic factors in an area

Prairie (grassland) ecosystem:

dominated by grasses and other non-woody plants called forbs.

Result from interactions between precipitation, temperature, landforms, soil drainage, fire, plants, and animals

habitat where an organism lives
Habitat: where an organism lives

What is the habitat for:

  • A bird?
  • A polar bear?
  • A salamander?
  • A raccoon?
niche how an organism affects and uses its environment
What is the niche for an earthworm?

Eats organic matter in soil

Fertilizes soil as it burrows and defecates

Is eaten by centipedes, birds, reptiles, amphibians, and small mammals

Niche: how an organism affects and uses its environment
what is the niche for
What is the niche for:
  • A bird?
  • An earthworm?
  • A polar bear?
  • A salamander?
  • A raccoon?



Nursery colonies

Adaptation: any characteristic which helps an organism survive in its environment. Four adaptations of a bat:

What helps species to survive?

  • Relationships with other species
  • Adaptations to that environment
  • Behaviors
relationships which help survival
Relationships Which Help Survival
  • Sometimes relationships between species help the survival of one or both species involved.
  • Examples of relationships:
    • Predator-prey relationships
    • Symbiotic relationships
      • Mutualism
      • Parasitism
      • Commensalism
predator prey relationships
Predator eats prey.

Both species benefit.

The predator gets energy from the prey

The prey populations are controlled by the predator.

Example: cheetah (predator) & gazelle (prey)

Predator-Prey Relationships
sybiotic relationships
Sybiotic Relationships
  • Symbiotic relationships: close permanent associations between species.
  • Three kinds:
  • Mutualism: Both species benefit
  • Parasitism: One species benefits, the other is harmed
  • Commensalism: One species benefits, the other isn’t helped or harmed.
Both species will benefit from the relationship

The acacia tree and the ant

The ant defends the tree against predators and clears out competition

The tree provides home and nectar to the ant

  • Gardenia thunbergia, a south African shrub, has fruits which never fall from the tree.
  • They are eaten by antelope and then the seeds are dispersed in the antelope dung.
  • Both the antelope and the shrub benefit.
Gardenia thunbergia also has a mutualist relationship with the hawk moth, who moves from plant to plant, lapping nectar and pollinating the plant with its long tongue.
One species benefits (the parasite) and the other is harmed (the host).

Parasitism is common in flowering plants.

Mistletoe is a parasite.

This dwarf mistletoe is growing on a Jeffery Pine.


Dodder, a relative of mistletoe, steals moisture and nutrients from laurel sumac in California.

(Above) A huge cowbird chick shares the nest with a smaller sparrow chick. (Top right) A Vireo feeds her baby and a cowbird nestling. (Bottom right) Cowbird eggs in a thrush nest.
  • Cowbirds are nesting parasites
  • They lay eggs in the nests of other birds.
  • The larger cowbird babies outcompete the other nestlings for food, often causing the host babies to die.
One species benefits, the other isn’t affected at all.

The clownfish is protected from predators by the stinging tentacles of the anenome. It secretes a mucus which keeps it from being harmed by the poison itself. The anenome isn’t affected one way or another by the clownfish.

  • Barnacles are crustaceans which attach to a stationary surface to live and feed.
  • Barnacles often attach to mollusks.
  • The barnacle gains a stable foothold, and the mollusk isn’t affected.
  • The cattle egret perches on grazers, eating the insects disturbed during the grazing process.
  • The larger animal isn’t affected, but the egret benefits from an increased food supply.

(a) predator-prey (b) mutualism

(c) Parasitism (d) commensalism (e) adaptation

__ A student selects the same food as the student in front of them because the first student knows what is good to eat.

__ A large brain allows students to learn biology

__ One student cheats off of another student

__ One student steals from another student

__ Two students study together and help each other with difficult concepts

__ A car drafts off of a truck on the interstate

__ Students go fishing and have a fish fry

characteristics which help survival
Characteristics Which Help Survival
  • Adaptation: Characteristics that species develop over time which help them to survive in their environment.
  • Important adaptations: opposable thumb, prehensile tail, jointed appendages, four chambered heart…
  • Special types of adaptation:
    • Camouflage
    • Mimicry

Opposable thumb: thumb that allows grasping and holding


Prehensile tail: tail that can function as a fifth limb and allows animals to hang from branches


Jointed appendages:

  • Arms and legs which can bend
  • Function in walking, feeding, fighting and mating.
  • First developed in arthropods.

Four chambered heart:

  • Separates oxygenated and deoxygenated blood
  • Allows more oxygen to reach tissues.
Any body structure or color which allows an animal to blend with its environment.

Camouflage helps animals hide from both predator and prey.

A canyon frog camouflaged against a canyon wall

A rock ptarmigan camouflaged against the landscape

A desert horned lizard in a sandy riverbed.

Walking stick

Praying mantis

(R) Katydids;

(below R) Geometrid moth;

(below) Red Diamondback Rattlesnake

(R) Crab spider;

(Below R) Pipefish in eelgrass;

(Below) Ambush Bug


Top left: Flatfish; Above left: Stone fish; Above right: Leafy Seadragon.

An animal mimics (copies) the appearance or behavior of a more dangerous or toxic species. Predators are fooled, and avoid both the venemous species and the mimic.

A bluejay eats a monarch butterfly and then vomits. The monarch is toxic to the bluejay. The bluejay will avoid eating the monarch now.

monarch or viceroy
Monarch or Viceroy?

In addition to avoiding the monarch, the blue jay will avoid eating the viceroy because it resembles the monarch. The jay can’t tell the difference.

behaviors which help survival
Behaviors Which Help Survival

Two kinds of behaviors:

  • Innate Behavior: instinctive behavior animals are born with
  • Learned Behavior: behaviors animals develop after birth through experience
innate behavior
Innate Behavior
  • Fight-or-flight: when confronted by danger, your heart speeds up, skin becomes sweaty and breath rate increases.
  • Territorial Behavior: Animals become aggressive defending their nest/territory.
  • Courtship/mating behavior: rituals in attracting a mate
  • Reflex: responses to environmental cues
  • Instinct: natural behaviors for particular situations (mothering, nursing)
territorial behavior
Territorial Behavior
  • Dogs/wolves define their territory by marking trees in their area through urination
  • Three-spined stickleback fish present their red belly to other animals in their territory. The other males respond by attacking or leaving.
courtship mating
  • Male turkeys display a plume for the female to see
  • The male spider captures a bug and wraps it into a silk web to present to the female as a gift
Knee-jerk reflex

Pulling your hand away from a hot object

Gag reflex: gagging when something touches the back of the throat

Frogs have insect detector cells in the retina of their eyes. When fly moves across their line of vision, their tongue jumps out and catches the insect.

Grey-lag goose: when egg falls from the nest, the mother will automatically roll it back into the nest.

Rabbits pull hair to line the nest before having a litter of babies.

Robins eat worms and then regurgitate into their offspring’s mouths to feed them.


Match: a) fight-or-flight b) Territorial behavior c) Courtship behavior d) Instinct e) Reflex

__ A female rabbit tries to bite when people put their hand in the rabbit’s cage

__ Cats arch their back and hiss when confronted by a dog

__ Alligators dig a hole to lay their eggs in, and then cover up the eggs with sand

__ Your eyes will blink when something moves quickly towards them

__ Male frogs give a particular call when trying to find a mate

__ Your arms will cover your face when something is thrown at your head

__ Cats rub against objects and people to place their scent on things in their surroundings

learned behaviors
Learned Behaviors
  • Habituation – getting used to a stimulus
  • Conditioned response: learning by association.
  • Imprinting: animals, at a certain critical time in their life, forms a social attachment with another object/animal
  • Learning by trial and error
Horses stop jumping after hearing the same loud sounds over and over

You don’t usually notice a clock ticking loudly after being in the room for a few minutes.

People who live in the city eventually stop noticing the sounds of traffic

conditioned response
Conditioned Response
  • When the bell rings, students run from the room.
  • When your dog hears you open the refrigerator, he comes to beg for scraps.
  • A mother bat and her pup imprint, and can find each other among millions of bat pups in a nursery colony by voice alone.
  • Zebra babies imprint on the first stripe pattern they see after birth. They will find and follow this pattern instantly within a huge herd of zebras.
  • Ducks will recognize and follow the first conspicuous object they see after birth, including humans and other animals.
trial and error
Jackdaw birds use trial-and-error to build better and better nests as they gain experience.

Mice learn through trial-and-error that they can get more food when chewing through sacks of grain in a barn.

Riding a bike is a trial-and-error process


Match: a) habituation b) trial-and-error

c) Conditioned response d) imprinting

__ getting up when the alarm rings

__ a baby calf recognizing his mother’s moo

__ a hunting dog not being frightened by the firing of a gun after constant exposure

__ a monkey learns how to get ants by putting a stick inside an ant mound

__ not noticing a bracelet after wearing it all day

__ heron get better at fishing with experience

quiz innate behaviors
Quiz: Innate Behaviors

Match: a) fight-or-flight b) Territorial behavior c) Courtship behavior d) Instinct e) Reflex

__ A female rabbit tries to bite when people put their hand in the rabbit’s cage

__ Cats arch their back and hiss when confronted by a dog

__ Alligators dig a hole to lay their eggs in, and then cover up the eggs with sand

__ Your eyes will blink when something moves quickly towards them

__ Male frogs give a particular call when trying to find a mate

__ Your arms will cover your face when something is thrown at your head

__ Cats rub against objects and people to place their scent on things in their surroundings





Trail and Error

Conditioned Response

Innate behavior

Any behavior which an animal is born with

Screaming when frightened

Getting out of bed when the alarm rings

Getting used to glasses on the nose so you don’t notice them

Jerking a hand off a hot stove

  • Getting better at algebra after doing practice problems
  • An opossum plays dead when threatened by a predator
  • Baby giraffes recognize mom by spot patterns
  • A teenager gets better at driving a car while driving on learner’s permit
population growth patterns
Population Growth Patterns
  • Environmental conditions control population growth.
  • Lots of food, few predators, disease = rapid population growth.
  • Poor environment (pollution, draught, habitat loss…) = negative or slow population growth.
graphs show how populations change or maintain their size
J-shaped curve: rapid population growth due to unlimited resources

S-shaped curve: initial growth, and then a leveling out of population growth when there are just enough resources to maintain the population.

Graphs show how populations change or maintain their size.
s shaped curve
S-shaped Curve
  • Growth of a yeast population in culture: after a period of exponential growth, the size of the population begins to level off and soon reaches a stable value.
j shaped curve
J-Shaped Curve
  • Human population growth from 10,000 B.C. until the present day
other kind of curves
Other Kind of Curves

When two species are cultured together, the less successful species will decline. The more successful species population will increase until the food source runs out, then it will also decline.

Lemmings = small Arctic rodents
  • population explosions every 3 to 5 years.
  • When population peak, lemmings migrate.
  • When they come to a stream they jump in and swim across.
  • Unfortunately, when they reach the ocean, they do the same and die in the sea.
Two frog populations on St. George’s island.
  • One was barely successful due to limited food supply
  • The other was very successful for about 20 years until a parasite wiped its food source
Snowshoe Hare and Canadian Lynx are dependent upon each other. The population of the hare is almost always greater than the population of the lynx. When hare populations are successful, the lynx population grows in response due to abundant food. As lynx populations grow, hare populations suffer, causing lynx populations to suffer also.
things affecting population size
Things affecting population size:

Limiting factor: anything which prevents rapid population growth. Two kinds:

  • Density dependent factors: biotic things affect population size. Examples: disease, famine, competition for resources and nesting sites
  • Density independent factors: abiotic things which affect population size. Examples: earthquake, flooding, fire
carrying capacity
Carrying capacity

Carrying capacity is when the environment has just enough resources to maintain the current population size.

In this graph of yeast grown in a culture, the culture was exposed to heat and all the yeast died. Was the limiting factor density dependent or density independent?
In this graph, a population of osprey grew until they ran out of nesting sites. The population leveled out at that time.

What was the limiting factor?

Was it density dependent or independent?

Which part of the graph shows where the population reached carrying capacity?

this graph shows a population of field mice
This graph shows a population of field mice.
  • What happened to the population near the end of the graph?
  • Name three possible density dependent limiting factors which may have caused this decline (other than what was named in the notes).
  • Name three density independent factors which may have caused this decline (not the ones listed in the notes)
comparing j curves and s curves
Comparing J-curves and S-curves
  • Which of the graphs shows that there were limiting factors?
  • Which of the graphs shows carrying capacity?
  • Does the s-shaped graph show limiting factors?
  • What do you think will happen to the J-shaped curve, given enough time?