Transcript Environmental Science Living Things in Ecosystems

LaVigne
Environmental Science
Living Things in Ecosystems
Chapter 2
Notes #3
10/09/08
2.1 Ecosystems
Biotic/Abiotic interactions
► Limiting
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Factors
Anything that controls a population
Rain
Food
Fire
????
► Carrying
Capacity
 # of a species that can be kept in an ecosystem
 Most populations vary above and below the carrying
capacity but stay near it.
2.2
How species interact with each other
►5
Major Interactions Among Biotic Factors
in an Ecosystem
 Predation
 Competition
 Parasitism
 Mutualism
 Commensalism
5.3 Adapting to the Environment
► Charles
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Darwin
an English naturalist (1859)
Sailed on the HMS Beagle 1600’s
King wanted inventory of his territory
Sailed to all British colonies
Saw many different types of plants & animals
► Darwin’s
Observations
 Saw finches on the Galapagos Islands
 Noticed that each island had finches that all fit the food
available on that island
 How can different beaks be on the same type of finch?
5.3 Adapting to the Environment
► Darwin
tried to make sense of his observations
 He proposed that the environment exerts a
strong influence over which individuals have
offspring
► Natural Selection – some individuals because of
certain traits are more likely to survive & have
offspring than others
 (there’s unequal survival/reproduction that results from
the presence or absence of particular traits)
5.3 Adapting to the Environment
► over
many generations characteristics
change- evolution
► adaptation – inherited trait increases an
organisms chance of survival & reproduction
in a certain environment
► Bears
 Similar animals in different environments have
different adaptations
 Polar bear- white, big feet, large size
 Black bear- black, small feet, medium size
►Each
has gone through selection over a long time in
their environments
5.3 Adapting to the Environment
5.3 Adapting to the Environment
► species
can evolve in response to each
other = coevolution
 Ex. A plant starts creating a chemical to prevent
animals from eating it and then the animal
gains the ability to detox itself from the
chemical
►Ex.
Cabbage butterfly caterpillars can break down
mustard oils, when many other animals cannot – so
it can feed on plants that other animals cannot
► extinction
– irreversible disappearance of a
population or species
5.3 Adapting to the Environment
► Theory
of Evolution Based on Natural
Selection
► Overproduction
► Variation
► Reproduction (passing on variation)
► Some variations are helpful
► Helpful variations make up more and more
of the population as time goes by
5.3 Adapting to the Environment
►
Antibiotics
 Dr. prescribes antibiotics and says “take these until they are all gone in
10 days”
 After 5 days you feel better
 Should you stop taking the pills?
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If you stop you may be helping select a stronger version of
your illness!!!!
 Why?
 Antibiotics are prescribed to help you by killing bacteria.
 After 5 days the weaker bacteria are dead, there are few left, and you
feel better.
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THE STRONG BACTERIA ARE ALIVE!
By not killing off all the bacteria you are helping to breed a
stronger strain!
Assignments
► Complete
the 2.2 Section review (#1-4)
 Definition of each interaction + ex on the back
 Hand it in
 Complete and hand in the video worksheet
packet from yesterday.
► Complete
the 2.3 section review (p 46, 1-4)
► Complete the Transparency ws #3