Download Population Dynamics

Warm-Up (2/16)
On the piece of white paper from the back, answer
the following question.
Between 1845 and 1852, the potato
population in Ireland decreased by as
much as 86% in what is known as the
Great Famine. It was caused by an
infestation of the parasite P. infestans
which rotted out potatoes and their
roots. State whether the Irish potato
population had high or low genetic
variation prior to the infestation and
justify your claim.
Name
Date
Period
2A.1e: Changes in free energy availability can result in changes in population size.
2A.1f: Changes in free energy availability can result in disruptions to an
ecosystem.
Illustrative example: Change in the producer level can affect the number and size
of other trophic levels.
2D.1c: The stability of populations, communities and ecosystems is affected by
interactions with biotic and abiotic factors.
Illustrative example: species diversity
4C.3a: A population’s ability to respond to changes in the environment is affected
by genetic diversity. Species and populations with little genetic diversity are at risk
of extinction.
Illustrative example: Potato blight causing the potato famine
4C.3b: Genetic diversity allows individuals in a population to respond differently to
the same changes in environmental conditions.
Illustrative example: Not all individuals in a population in a disease outbreak are
equally affected.
4C.4a: Natural and artificial ecosystems with fewer component parts and with little
diversity among the parts are often less resilient to changes in the environment.
4C.4b: Keystone species, producers, and essential abiotic and biotic factors
contribute to maintaining the diversity of an ecosystem. The effects of keystone
species on the ecosystem are disproportionate relative to their abundance in the
ecosystem, and when they are removed from the ecosystem, the ecosystem often
collapses.
Population Dynamics
Ecosystems are composed of
abiotic and biotic factors.
abiotic factor – non-living
water
soil
air
Population Dynamics
Ecosystems are composed of
abiotic and biotic factors.
abiotic factor – non-living
biotic factor – living
plants
microbes
animals
Population Dynamics
Like levels of transcription factors in
development, interactions of biotic and abiotic
factors affect the stability of an ecosystem.
California, 2011
California, 2014
Which abiotic
factor changed?
Which biotic
factor changed?
Population Dynamics
Like levels of transcription factors in
development, interactions of biotic and abiotic
factors affect the stability of an ecosystem.
Which abiotic
factor changed?
Which biotic
factor changed?
before algae bloom
after algae bloom
Population Dynamics
lower the species diversity, lower the stability
Before a disease outbreak:
All the possible corn varieties
Monoculture corn farm
Population Dynamics
lower the species diversity, lower the stability
After a disease outbreak:
All the possible corn varieties
Monoculture corn farm
Population Dynamics
higher the species diversity, more varied the response
before drought
after drought
okay
weak but
alive
alive and
strong
dead
dead dead
dead
dead
Population Dynamics
Changing levels of
producers or keystone
species drastically
affects ecosystems.
Keystone
species
Producers (plants)
Review
• Calculating p and q based on recessive numbers.
• How to determine if two species are different:
• do they produce viable offspring?
• does their DNA compare?
• same number of chromosomes?
• Pre- and post-zygotic isolation mechanisms
•
•
•
•
•
•
Physical isolation (pre)
Different mating seasons (pre)
Sexual selection (pre)
Offspring survival (post)
Hybrid fertility (post)
Chromosome compatibility (post)
zygote
Critical Thinking Question #1
Severity of Outbreak
(% fatal after two weeks)
The graph below shows the response of a population to a
disease outbreak. The percentage of individuals who died
after two weeks of exposure to the disease with a certain
genotype is plotted below.
90%
80%
70%
60%
50%
40%
30%
20%
10%
0%
AA
Aa
Genotype
aa
Using evidence from the graph, explain how genetic
variation contributed to a variety of phenotypic responses to
the disease outbreak. (LO 4.25)
Critical Thinking Question #2
Ecological succession is a process by
which species diversity increases over time
as new species colonize a habitat following
a natural disaster (such as a forest fire).
Predict how the stability of the ecosystem
changes during ecological succession. (LO
4.27)
Closure
On the piece of white paper from the
back, answer the following question:
Cowbirds primarily feed on
herbivorous insects which obtain
all of their energy from plants.
Predict the effects on the bird
population during a major
drought.
Name
Date
Period
Scale
1 – 10