1. Warm-Up (2/16)
On the piece of white paper from the back, answer the following question.
Name
Date
Period
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.

2. 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.

3. Population Dynamics
Ecosystems are composed of abiotic and biotic factors.
abiotic factor – non-living
water
soil
air

4. Population Dynamics
Ecosystems are composed of abiotic and biotic factors.
abiotic factor – non-living
biotic factor – living
plants
microbes
animals

5. 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?

6. 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

7. Before a disease outbreak:
Population Dynamics
lower the species diversity, lower the stability
Before a disease outbreak:
All the possible corn varieties
Monoculture corn farm

8. After a disease outbreak:
Population Dynamics
lower the species diversity, lower the stability
After a disease outbreak:
All the possible corn varieties
Monoculture corn farm

9. higher the species diversity, more varied the response
Population Dynamics
higher the species diversity, more varied the response
before drought
after drought
okay
alive and strong
weak but alive
dead
dead
dead
dead
dead

10. Population Dynamics
Changing levels of producers or keystone species drastically affects ecosystems.
Keystone species
Producers (plants)

11. Review zygote 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

12. Critical Thinking Question #1
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.
Using evidence from the graph, explain how genetic variation contributed to a variety of phenotypic responses to the disease outbreak. (LO 4.25)

13. 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)

14. Closure
On the piece of white paper from the back, answer the following question:
Name
Date
Period
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.
Scale 1 – 10