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.

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

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

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

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

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

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

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)

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: 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