Predation

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Predation

• The Great Circle of Life
• THE LION KING

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What is Predation?

• Predation is the situation in which members of a
  predator species prey on members of a prey
  species, but do not live in or on the prey.
• Predator prey relationship
• -the relation ship between predator and
• prey, (lynx and hare)

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What is a predator

• Any species that preys on another species
• Meat eaters-anything from carnivorous plants to
  humans and killer whales. We all eat meat
• Herbivores- you better believe it. Those little
  bunnies in your yard are in fact predators

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Who is prey?

• Any species preyed on by another species.
• Any species can technically be prey.
• Prey generally have characteristics that make
  them susceptible to being prey.
• Plants cannot move, hence bunnies can eat plants
• Bunnies are little and slower than coyotes, hence
  coyotes prey on bunnies

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Predation feedback systems

• Positive feedback for the predator, always gets
  to eat prey
• Limited by negative feedback when prey population
  falls resulting in lack of food for predators
  causing a decrease in predator population

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Predator Strategies

• Ambush-
• Tigers and other species use camouflage to stalk
  a victim for a sudden attack
• Other animals, such as eel hide and spring
  attacks on unsuspecting victims
• Birds of Prey use keen eyesight and can plan an
  ambush from above without being detected by prey

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Predator Strategies

• Pursuit
• Animals with natural advantages use theses
  advantages to pursue their victims
• Cheetahs can run faster than their prey, thus
  enabling them to catch prey
• Species like Lions or Wolves hunt in pacts,
  isolating a victim and then work together to kill
  their prey

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Prey Strategies

• Structural advantages
• Hard Body Coverings, Armadillos have hard outer
  layers and can roll into tight hardballs to
  protect from predators, also Turtles, Tortoises
• Thorns or Spines- Cacti, Porcupines
• Break away body parts- lizards, starfish
• Natural Weapons-Horns, Hoofs, Size

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Prey Strategies

• Defense Techniques
• Inflation- blow fish
• The Flee- Antelope have mad speed, monkeys and
  squirrels can climb trees where they have the
  mobility advantage
• Fight Back- with thorns, horns and hoofs
• other good fighters- cowboy crab and surgeon fish

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Predator and Prey Adaptations

• Camouflage
• Quick Color Changers- chameleons, octopuses,
  flounders
• Seasonal Color Changers- white-tailed ptarmigan
• Natural camouflage- lions, tigers, frogs,
  scorpion fish

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Chemical Warfare

• Predators
• Venom- Reptiles and Arachnids
• Prey
• Octopuses and other Sea Animals use blinding ink
• Poison- Dart Frogs, insects, reptiles and many
  Plants
• Offensive Smells and Tastes

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Mimicry

• Mostly a prey technique
• Optical and sonic illusions- zebra stripes,
  fringed moth wings
• Seems like a predator, school of fish, false
  eyes, frilled neck and inflation

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THEEND
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Parasitism
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What is parasitism?

• Definition
• An organism that obtains its nutrients from a
  limited number of host individuals, normally
  causing harm but not causing death immediately
• Predation vs. Parasitism
• Predation predator devours prey
• Parasitism can indirectly kill prey
• usually eats live prey

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Symbiosis

• and - relationship
• parasite
• host -
• parasite usually smaller than host

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Where parasites fall into...

• Endoparasites
• live within their hosts
• ex bacteria and viruses
• Ectoparasites
• grow on their host
• ex fleas and ticks

• Microparasites
• Live within the intracellular space
• Macroparasites
• Live within intercellular space
• Both fall into the Endoparasite group

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Affects on Agriculture

• Many farmer try to reduce populations of
  parasites
• affects output of food
• pesticides

• Pesticides
• can strengthen the parasite population
• further use
• ex DDT

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Parasite Techniques

• Bore holes into the skin to suck blood of host

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Parasite Techniques Contd

• Using cell to multiply species
• viruses

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Thank You For Watching the Wonderful World of
ParasitesMaybe someday they can return the favor
of your viewing
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Mutualism

• Working Together for the Benefit of Each Other

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What is Mutualism?

• A symbiotic relationship in which both
  interacting species benefit in various ways
• Positive reciprocal relationship between two
  species
• both species enhance survival, growth, fitness

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An Explanation of Mutualism continued

• More a reciprocal exploitation than cooperative
  effort on the part of the individuals involved
• basically two organisms interact in such a way
  that both obtain something helpful out of the
  relationship
• a relationship where one, or both, could not
  exist without the other

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Forms of Mutualism

• Symbiosis both organisms live together in close
  proximity and in which both generally derive
  benefit
• called obligate -one species directly involved in
  order to survive

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Forms Continued

• Non-Symbiotic Relationship species do not live
  together, not dependent on each other
• relationship faculatitive or opportunistic but
  does profit the organisms when together

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The evolution of mutualism

• The relationship has evolved from more negative
  associations, a.k.a., predator/prey, parasitism
• basically organism negatively impacted had two
  options
• escape relationship
• or adapt to it
• in the process make it self-advantageous

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An example of Mutualism

• The ant and the black aphid
• In this relationship, the ant protects the black
  aphids eggs, meaning, he feeds them, tends them,
  keeps them safe from insects interested in an
  unborn meal
• In return the black aphid supplies the ant with
  food with honeydew it actually secretes

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A popular form of mutualism

• Pollination relationship between flowering plants
  and insects
• flowers need insects, bees and butterflies, and
  animals, bats and birds, to assist them in the
  reproductive cycle
• birds, bats, butterflies, bees take food in form
  of nectar and pollen

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Ecosystem Stability and Species Equilibrium Models
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Ecosystem Stability

• Ecosystems are relatively stable over time
• a rain forest today will look similar to the rain
  forest in its place a hundred years from now
• Ecosystems have a stable number of species over
  time, although species turnover will change the
  specific species in an ecosystem over time

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Ecosystem Stability

• What are the three types of stability?
• Persistence ability of an ecosystem to resist
  disturbance
• Constancy ability of a population to maintain
  adequate population size
• Resilience ability of an ecosystem or population
  to bounce back after a disturbance

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What are the characteristics of stable ecosystems?

• complex food webs
• generalist species
• high species diversity
• complex species interactions
• high primary productivity
• low to moderate climate variation
• However, no cut and dry rules (at times, simple
  can be stable too

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What determines how many species will exist in an
area?

• Species Equilibrium Model
• or, the
• Theory of Island Biogeography

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The Theory of Island Biogeography

• The theory was originally established for
  islands, but can be adapted to any habitat
  island
• The number of species on an island is determined
  by the balance of extinction and immigration
• After some time, the immigration rate and
  extinction rate will be equal equilibriujm
  number of species on island

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The Theory of Island Biogeography

• The theory was originally established for
  islands, but can be adapted to any habitat
  island
• The theory looks at the question from a
  historical perspective How did the island get
  from no species to the stable number that it has
  now?

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The Theory of Island Biogeography

• The number of species on an island is determined
  by the balance of extinction and immigration

Immigration rates start out high, because each
species to hit the island is likely to be a new
species, and will successfully immigrate Over
time the number decreases because there are no
new species left to colonize, and immigration is
difficult
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The Theory of Island Biogeography

• The number of species on an island is determined
  by the balance of extinction and immigration

Extinction rates start out low because there is
little competition for abundant resources Over
time, that number increases as species become
extinct due to competition, predation, or random
fluctuations in the environment
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The Theory of Island Biogeography

• The number of species on an island is determined
  by the balance of extinction and immigration
• After some time, the immigration rate and
  extinction rate will be equal equilibrium
  number of species on island

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Affect of Island Area on Species Equilibrium

• Larger islands have a larger catching area which
  results in higher rates of immigration
• Larger islands have lower rates of extinction
  because of a more diverse habitat more niches to
  fill, more resources

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Species-area relationships

• The island biogeography model predicts, and most
  people agree, that there is a positive
  relationship between the number of species (and
  species diversity) and the area of a piece of
  land
• This is called the Species-area relationship

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Affect of Island Distance from Mainland on
Species Equilibrium

• Nearer islands have higher rates of immigration
  because there is a greater chance that organisms
  will immigrate to the island

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So, how does this apply to environmental science?

• As humans destroy habitat, we are leaving habitat
  fragments behind
• This theory can help us answer
• Should we preserve this fragment?
• Would it be better to give up this small fragment
  in exchange for saving a larger one?
• Is this fragment close enough to untouched land
  to be able to be a viable piece of land for
  organisms to colonize?
• Etc...

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Species Diversity

• Species diversity is a measure of the number of
  species there are in an ecosystem plus the
  distribution of individuals in all species
• The most diverse ecosystems are those that have
  the greatest number of species, and the most
  even distribution.
• The species-area relationship suggests that the
  greatest diversity should be in the largest
  habitat areas

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Calculation of Species Diversity

• One diversity index is the Shannon-Weiner
  Diversity Index
• It is calculated as H -
• pi the number of individuals in one species
  divided by the total number of individuals in all
  species

• pi log pi

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Calculating Diversity Example
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The good and the bad

• Good
• can compare different ecosystems in different
  habitats
• reflects number of species and eveness
• Bad
• means nothing by itself
• doesnt reflect biomass or individual size
• no units

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Species Richness

• Species richness is often calculated as the
  number of species in an environment
• In the previous example, it would be 5