Download Chapter 6 Highlights - Orting School District

Chapter 6 Highlights
Mrs. Thompson
APES 2014
Warm Up
• What is the difference between Population,
Community, Ecosystem and Biosphere?
Objectives
• Predict whether a change will increase or
decrease a population
• Identify the limiting factor(s) for a population
• Use appropriate graphs and equations to
represent population dynamics
• Describe interactions between species
• Explain the concept of ecological succession
Population
• Can be described using
– Size
– Density
– Distribution
• Turn and talk with table mates…..What do
each of these terms mean? How would you
measure each?
Population Size
• How many individuals of a species are found
within a defined area
• Count them…..but what if we can’t count
them all?
• We will do a catch and release lab to address
this question
Population Size
• Predict which of the following factors increase
population size….and which decrease population
size
–
–
–
–
–
–
Disease
Competition for mates
Increased death rate
More food
Limited habitat
Increased predator
population
– Immigration
– Emigration
–
–
–
–
–
Drought
Increased Nitrogen
Flood
Increased sunlight
High rate of
reproduction
– Increased prey
population
Can be divided into two categories
• Density Dependent
–
–
–
–
–
–
Disease
Competition for mates
Limited habitat
Fighting
Competition for food
Competition for sunlight
– “Limiting factor”= which
ever resource
determines the carrying
capacity (K)
• Density independent
•
•
•
–
–
–
–
–
High birth rate
Extra rain = more food
Short lifespan
Drought
Increased Nitrogen
Flood
Increased sunlight
High rate of reproduction
Population Density
• Number of individuals of a species found
per unit of area
• Count them and then divide by the area
• (This should be review from Biology)
Population Distribution
• The pattern of how a population of a species
occupies space (also review from biology)
– Random
• Most common for plants that have wind or animal
spread seeds
– Uniform
• Requires uniform access to resources
• Common in controlled environments….such as farms or
territorial animals such as wild cats
– Clumped
• Provides protection from predators
• Herding animals, schooling fish, flocks of birds
Population Distribution
Modeling Populations
Logistic Growth Model
• Species experiences
exponential growth, but
levels off when it reaches
carrying capacity
Exponential Growth Model
• Requires unlimited
resources and no density
dependent interactions
• Make sure that you can
calculate exponential
growth
Reproductive Strategies
K- Selection
R-Selection
Reproductive Strategies
K- Selection
• Low birth rate
• Slow population growth
• Controlled by the Carrying
Capacity (K)
• Usually organisms that
produce few, large, slowly
maturing, and high parental
care offspring
• Regulated by density
dependent factors
• Difficult to save from
extinction
R-Selection
• High birth rate
• Rapid changes in population
• Frequently overshoot
carrying capacity followed
by die-off
• Usually organisms that
produce many, small, fast
maturing, offspring
requiring little to no
parental care
• Regulated by density
independent factors
Survivorship Curves
K-selection
• Type 1 Curve
R-selection
• Type 3 curve
Warm Up
• List several issues that might arise when
attempting to measure a population in the
field
Population Studies
• Mark and recapture
• Used to make estimates of population size and
density
• Calculated using proportions
# of tagged = # recaptured
total pop
# captured
Animal Cracker Mark and Recapture
• #1 Wash your hands…..
•
•
•
•
•
Each group will “collect one cup of crackers”
Mark and count only the koala bears
Dump the cup of crackers back into the container
Mix them up
Count how many koala bears were captured and
how many captured were also tagged
Random Sampling Methods
• Provide
UNBIASED
samples for
analysis
• Must start
with a
homogenous
section of the
study site
Sampling using a quadrat
one of the simplest
ways of sampling a
habitat
a quadrat: a square
frame made of wood
or metal
 A quadrat
Sampling using quadrats
to use the quadrat…




Generate a random coordinates of the
site
put the quadrat at the random location
Count the plants and animals inside it,
ignore anything outside the quadrat
repeat the process again in different
parts of the field
Sampling using quadrats
to use the quadrat…

calculate the average number of
individuals per unit square for each
species and measure the area of the
habitat under study to estimate the
density of each speices
Sampling using quadrats
limitations


it will be hard to count fast-moving
animals, this method is limited to
vegetation
and
slow-moving
or
stationary animals
the quadrat must also be placed on a
fairly flat piece of land
Activity 19.5
Sampling using a line transect
this method is used to record exactly
where each species or type of organism is
found
a line transect can be made from a string
marked at regular intervals
 it is stretched across the habitat you
want to examine
 all the organisms touching the string
are recorded with their distance from
one end of the line called the ‘origin’
Sampling using a line transect
 How to make a line transect, and illustrate the
results with a profile diagram
regular internal
marks
stake
line transect
origin
graph paper
height
(m)
soil
1m
0
1
2
3
4
5
distance from origin (m)
6
7
8
Sampling using belt transects
a better method than line transect
belt transect is made by:
 laying out two parallel strings, perhaps
one metre or less apart and record the
plants between them
 or placing quadrats continuously or in
regular intervals along a transect line
Quadrat 1 Quadrat 2 Quadrat 3 Quadrat 4 Quadrat 5
1m
 A belt
transect
Sampling using belt transects
the distribution and relative abundance of
different species along the belt transect
can be studied
Community
• Species Interactions
– Competition
– Predator/Prey (Herbivores are predators! )
– Symbiotic Relationships
• Parasitic
• Mutualistic
• Commensialist
Competition
• Competitive Exclusion Principle
– States that two species that compete for the same
limiting resource CANNOT coexist
– May lead to
• Resource partitioning (niche)
– Temporal (time)
– Spatial
– Morphological
• Extinction
Predator Prey Graph
• Interactions result
in a cyclic pattern
of population
growth and decline
Deer Me activity--Modeling a predator – prey
relationship
• RULES:
– All animals must stay within the forest (any that
don’t fit starve and die)
– Start with 3 deer- after each generation, all
surviving deer reproduce one offspring
– Deer CANNOT over-lap in the forest
– A wolf must eat at least one deer to survive
– A wolf must eat at least 3 deer to reproduce
– If you run out of wolves, a wolf from a nearby
pack will immigrate to your forest
Symbiosis
Identified by effect on the host
• Parasitic
– Host Harmed
• Mutualistic
– Host Benefits
• Commensialist
– Host neither harmed or Benefits
• Turn and talk- Come up with an example for
each type of relationship
Species Richness
• How do each of the following impact the
number of species present in a community
– Latitude (Ie. Amount of sunlight/temperature)
– Time
– Habitat size
Species Richness
• Latitude
– The more sunshine, the more produces, the more
consumers that can be supported
• Time
– The longer an ecosystem is in existence, the more
time for genetic and species diversity to increase
• Habitat size
– The more space available, the greater the room
for different species
Species Richness
• Intermediate disturbance hypothesis states
that mild disturbances such as occasional fire
or floods increase species richness
• May allow for invasive
species population
Ecological Succession
• Primary
– Soil layer removed or
covered
– Recovery must first
establish a soil layer
– Debris flows
– Glacial Retreat
– Lava flow/ volcanic ash
– Urban development
• Secondary
– Soil layer and seed bank
remains intact
– Flood
– Fire
– Deforestation
– agriculture
Ecological Succession