by Tracy Reynolds

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Chapter 5

• by Tracy Reynolds
• Rose, period 7

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How do species interact?

• 5 Major interactions
• Interspecific competition- occurs when members of
  two or more species interact to gain access to
  the same limits resources such as food, light, or
  space.
• Predation- occurs when a member of one species
  feeds directly on all or part of a member of
  another species.
• Parasitism- occurs when one organisim feeds on
  the body of, or the energy used by, another
  organism, usually by living on or in the host.
• Mutualism- an interaction that benefits both
  speciesby providing each other with food,
  shelter, or some other resource.
• Commensalism- interaction the benefits one
  species but has little, if any, effect on the
  other

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Competition for Resources

• The most common intereaction between species is
  competition. Each species has its oen ecoligical
  niche. Some have broad nices, and some have
  narrow ones. When two species compete for the
  same reasouces such as food, the niches overlap.
  When overlapping, the competetion gets more
  intense. Its very un common to find two spices
  sharing the same exact niche, and if the do, one
  species is always more dominant. Wich forces the
  other species to go extinct, change eating
  habits, or migrate to a new area.

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Most Consumer Species feed on live organisms of
other species

• In predication, a member of one species (the
  predator) feeds directly on all or part of the
  living organism of another plact or animal
  species (the prey) as a part or a food web.
  Together, the two different species, such as
  lions and zebras, form a predator-prey
  relationship.

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Most Consumer Species feed on live organisms of
other species

• Things such as herbivores, carnivores, and
  omnivores are predators, but technically not
  because they do not have to feed on live
  organisms. If you do prey on a live organisms,
  there are so many different ways the predators
  capture their prey. Things like camouflage,
  flying, speed (running), ambush, or even chemical
  warfare (venom).

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Most Consumer Species feed on live organisms of
other species

• Even though the predators have advantages, so do
  the prey. Things like protective shells, speed,
  flying, and chemical warfare. An example is like
  a skunk letting off its stench to scare away the
  predator.

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Predator and Prey species can drive each other
evolution

• When two different species interact for a long
  period of time, the gene pool can blend together
  and cause changes. Changes can help both sides
  become more competitive and reduce competition.
  They call this process, coevolution. Coevolution
  is like an arms race between interacting
  populations of different species. Sometimes
  predators, get the upper hand, then sometimes the
  prey does. Its one of natures way of maintaining
  long-term sustainability through population
  control, and it can promote biodiversity by
  increasing species diversity.

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Some Species feed off other species by living on
or in them

• This is parasitism, the parasite is usually
  smaller than the host. They gradually over time,
  draw nourishment for them from the host to
  gradually weaken them. Some also live inside the
  host, such as tape worms, or move move arond,
  like ticks.

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Both species benefit

• Mutualism, Both species provide each other with
  things like food and shelter. An example is the
  birds that ride on the back of large animals like
  buffalo and elephants, they eat the parasites and
  and pests off of them. They also make noise
  warning the larger animals when predators
  approach.

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One species benefits, and other unharmed

• Commensalism, an interaction that benefits but
  has has little or no effect on the other. An
  example, certain kinds of silver fish incests
  move alone with army ants to share the food, and
  the arms ants are unharmed, but have no benefit
  from it.

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some species evolve to share resources

• Some populations compete for the same resources
  and have to develop adaptation through natural
  selection. They do this to reduce competition, or
  you could say reducing niche overlapping. This
  happens through resource partitioning.

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population dynamics

• Populations differ in factors such as
  distribution, numbers, age structure and density.
  Population dynamics is specifically the study of
  how characteristics of populations change in
  response of change in the environment.

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clumping

• Animals live in clumps for
• protection
• better resources
• hunting in packs
• mating

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population growth, or shrinkage, or stability

• Can change due to, births, deaths, immigration or
  emigration.
• Emigration departure of individuals from the
  population.
• Immigration arrival of individuals from outside
  population

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population growth, or shrinkage, or stability

• Population increase can cepende on the age
  structure, with is the amount you have of each
  age group. To young to reproduce, the once that
  can reproduce, and the ones to old to reproduce.
  Generally most population should have most of the
  age of the ones that can reproduce.

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J-curve and s-curve

• Species vary in biotic potential, or capacity for
  population growth under ideal conditions.
  populations with larger spices like elephants,
  have low biotic potential. The smaller species
  have high biotic potential.

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J-curve and s-curve

• instinct rate of increase is the rate at which
  the population of a species would grow if it had
  unlimited resources.
• environmental resistance combination of all
  factors that act to limit the growth of all
  population.
• carrying capacity maximum population of a given
  species that a particular habitat can sustain
  indefinitely without being degraded.

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J-curve and s-curve

• A population with few, if any limitations in its
  resources can grow exponentially at a fixed rate
  such as 1 or 2 per year. Exponential or
  geometric growth starts slowly but then
  accelerates as the population increases, because
  the base size of the population is increasing.
  Plotting the number of individuals against time
  yields a J-shaped growth curve.

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J-curve and s-curve

• Logistic growth- involves rapid exponential
  population growth followed by a steady decrease
  in population growth until the population size
  levels off.
• A plot of the number of individuals against time
  yields a sigmoid, or a S-shaped, logistic growth
  curve.

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exceeding habitats carrying capacity can cause
its population to crash

• Some populations can over use all their resources
  and temporarily over-shoot. This occurs because
  of a reproductive time lag, period needed for the
  birth rate to fall and death rate to rise in
  response to resource overconsumption.

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Different reproductive patters

• Species capable for a high rate population
  increase are called r-selected species. Usually
  have many small offspring, and dont show much
  parental activity. A lot of them die, so they can
  start the reproductive pattern again.
• They can also be called opportunists, the
  reproduce repidly when conditions are favorable.

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Different reproductive patters

• Another one is called competitor or K-selected
  species. Reproduce later in life, very few off
  spring, and have lomg-term lives. They develop
  inside their mothers, come out fairly large,
  mature slow and are cared for by their parents.

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Human population control

• Things like bubonic plague, killed at least 25
  millon people.
• AIDS has also killed atleast 25 million people.

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Ecological Succession

• The gradual change in species composition in a
  given area.

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Ecological Succession

• Primary Succession gradual establishment of
  biotic communities lifeless areas.
• Secondary Succession a series of communities
  with different species develop in places
  containing soil or sediment.

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primary succession

• Begins in a very lifeless area, or bottom
  sediment in aquatic system.
• Usually takes awhile to start, but rock
  eventually starts to weather relasing nutrients.

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Secondary Succession

• Begins where an ecosystem has been disturbed,
  removed, or destroyed but some soil and bottom
  sediment remains. Things like cut down forest, or
  abandoned farmland.

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succession has no specific path

• According to traditional view, succession
  proceeds in an orderly sequence along an
  unexpected path until a certain stable type of
  climax community occupies an area.
• Over the lasy several decades ecologist have
  changes their views about balance and equilibrium
  nature. The current view is that we cannot
  predict the course of a given succession or view
  it as preordained progress toward an ideally
  adapted climax plant community or ecosystem.

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Living systems are sustained through constant
change

• It is useful to distinguish among two aspects of
  satiability in living systems. One is inertia, or
  persistence the ability of a living system, such
  as grass land or forest, to survive moderate
  disturbances. A second factor is resilience the
  ability of a living system be restored through
  secondary succession after a moderate
  disturbance.
• However, there are limits to the stressed that
  ecosystems and global systems such as climate can
  take. As a result, such systems can reach a
  tipping pint, where any additional stress can
  cause the system to change in an abrupt and
  usually irreversible way that ofteninvolves
  collapse.

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