Transcript Population - Community Unit School District 308

Populations &
Communities
Unit 1
Ecology is…
• The scientific study of the interactions between
organisms and the environment
Biotic vs. Abiotic Factors
• Biotic: living components
o Ex: live or dead organisms, waste, by-product…
• Abiotic: non-living components
o Ex: light, soil, water…
Abiotic Shapes Biotic
• These abiotic factors create different
environmental conditions on the planet
• Biotic life has evolved to live in these areas
Organisms to Biosphere
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Organism: one individual life form
Species: one type of organism or a group
Population: group of the same species
Community: collection of populations
Ecosystem: community and the environment
Biosphere: global ecosystem (Earth)
Population Studies
Population
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A group of individuals,
Of the same species,
In one area,
At one time.
Ex: Number of dogs in
Oswego in 2005
Estimation of NumbersQuadrat
Random Sampling/Quadrat
Sum of organisms in grids/#
grids used.
Multiply by total number of
grids.
EX: Count the sea urchins in
the highlighted grids.
1+1+2+1=5÷4 grids used = 1.25
urchins per grid
Multiply by the total number
of grids
1.25x11x11= 151 urchins
Capture-RecaptureLincoln-Peterson
• You will
compare
numbers
marked to
what you
recaptured
with and
with out
marks.
Capture RecaptureSchnabel Index
• Reduces over estimations unlike Peterson and
completely dependent on number of samples taken.
Population Density
• # of individuals per unit area
• Ex: A farmer has 2 cows per square acre of land.
Population Growth
•
•
How a population changes over time
May stay the same, increase (+), or decrease (-)
Factors That Affect Pop.
Size
+
• Natality (births)
• Immigration
o Individuals move into
an area
• Mortality (deaths)
• Emigration
o Individuals leave an
area
Carrying Capacity
• Largest number of individuals of a given species an
environment can support with its available
resources
Limits to Population
Growth
• Limiting Factors
o Causes population growth to slow
o Can be biotic or abiotic
Density-Dependent
Factors
• Limiting factors that depend on population size
(density matters)
• Competition
• Stress
• Predation
• Parasitism
• Disease
Density-Independent
Factors
• Limiting factors that do
not depend on
population size
(density doesn’t
matter)
• Weather
• Natural disasters Chinese forests being
cleared for timber and
• Human activities farmland, so pandas are
running out of food and
• Behaviors
places to live.
Draught has
caused this
river bed to
dry up.
Distribution Patterns
Density
• Amount of organisms in a measured area
• Formula:
• Population Density = # organisms/area
Density Problems
• EX: There are 7 squirrels counted in a 3 acre plot
during the Spring of 2014. After a severely cold and
snowy winter, there are only 3 in the spring of 2015.
Density of 2014
7 squirrels/3 acres = 2.3 squirrels per acre
Desnity of 2015
3 squirrles/3 acres = 1.0 squirrels per acre
Community Relationships
Competition & Niche
• Niche: the location and resources an organism
consumes
• Competitive Exclusion Principle: two types of
organisms cannot exist in the same niche with the
same population health
Figure 54.4 shows that when two species of finch coexist, their beak sizes
diverge, which is character displacement. If the two species colonized an
island on which there were seeds of only one size, what would Gause’s
principle of competitive exclusion (page 1199 in the textbook) predict?
A. The finches would hybridize and
become one species.
B. G. fuliginosa would evolve small
beaks, and G. fortis would
evolve large beaks.
C. One of the finch species would
probably disappear from the
island.
D. The plants would evolve seeds
of different sizes.
E. It is impossible to predict the
outcome
Copyright © 2008 Pearson
Education, Inc., publishing
as Pearson Benjamin
Biodiversity & Simpson’s
Index
• Richness is amount of different species
• Evenness is relative number compared to other
species.
Compare the two communities based on richness and
evenness.
Succession
• Succession: when a ecosystem is disturbed and
recovers
o Primary- first, no soil, very long time, lichens (pioneer)
o Secondary-after soil is established, climax community (keystone)
• Quick Clip:
https://www.youtube.com/watch?v=E0qdWoLdk1c