Download Populations

Warm Up
•List the 4 biogeochemical
cycles:
1
ECOSYSTEM DYNAMICS
•Populations
•Symbiosis
•Succession
http://www.nps.gov/pete/forteachers/life-in-an-ecosystem.htm
Populations
• Group of the same type of organism living
in the same geographic area at a given
time.
• Limiting Factor – Causes a population to
decrease in size. Examples: food, water,
shelter, space
• Sunlight in a rainforest = limiting factor
• Carrying Capacity - maximum population
size that an environment can contain
Measuring Populations
• Census – count all of the
organisms in a population
• Direct count
• Sampling – count a small
sample and use it to estimate
the total population
Techniques for
Sampling
• Quadrat Method
• Good for counting sessile things
• Sessile = NON MOVING
• Construct a grid
• Count several random quadrats
http://www.psychology.ex.ac.uk/lundy/images/quad.jpg
Capture-Recapture Method
• Assumes population remains
constant
• Capture, mark and release
organisms
• Capture again, use formula:
Mark – Recapture of Snakes
https://www.youtube.com/watch?v=5DR50IgvE7g
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Population Density
• Need: population size and area
• Ex. 40 oak trees in 10 acres
Population Distribution
• Clumped
• Uniform/Even
• Random
Symbiosis
Species Interaction
• Predation
• Predator – consumes another individual,
the prey
• Plants – adaptations to prevent
predation (thorns)
http://www.public.iastate.edu/~bsbowen/ZOOL-EEOB507/images/predprey-cheetahgazelle.jpg;
http://www.bigfoto.com/themes/closeup/thorn-photo_if.jpg;
http://www.ndpteachers.org/perit/Tapeworm%5B1%5D.JPG
Parasitism
• Parasite – feeds on host, harming
but not killing it
• Ectoparasite – external (ticks)
• Endoparasite – internal (tapeworm)
http://www.public.iastate.edu/~bsbowen/ZOOL-EEOB507/images/predprey-cheetahgazelle.jpg;
http://www.bigfoto.com/themes/closeup/thorn-photo_if.jpg;
http://www.ndpteachers.org/perit/Tapeworm%5B1%5D.JPG
Competition – species compete for
same limited resource (water)
• Mutualism – both species benefit
•
(clown fish, sea anemone)
• Commensalism – one species benefits,
the other unharmed
(human, apple tree)
http://www.sandyart.com/Clown_Fish_.jpghttp
Symbiosis Examples
https://www.youtube.com/watch?v=8rSlA_ywEec
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Succession
• The gradual change in a community over
time.
• Primary community – development of a
community where none existed before.
• (Bare rock succession)
• Secondary community – reclamation of a
previously existing community
• (Farmer’s field succession)
• Climax community – long-term, generally
stable
•
( Old forest community)