Please Do Now: 1) List the 3 types of selection 2) Do your best to explain what those three words mean

Agenda Do Now Data Analysis Types of selection notes Types of selection worksheet

Data Analysis You will be a presented a series of graphs and charts (every Thursday) For each chart or graph, on a blank sheet of paper you will answer 1-2 questions. Once we have gone through all of them, you will be posed a question that unifies all the figures. Respond in 3-4 sentences.

Data Analysis 1. What is being measured in this graph? 2. Did that variable change during the period of measurement? 3. What is on the y-axis of this graph? 4. Come up with a hypothesis for why this happened.

Data Analysis 5. How is this graph different than the previous graph? 6. Does this graph show the same results? Or are they different? Explain. 7. Does this graph support your hypothesis from the last graph?

Data Analysis Using what you learned from the previous graphs, and this graph here, do you think there is strong selective pressure (is it important in evolution for these finches? Explain your answer.

What are selection pressures? Factors that are shaping the evolution of a population Common examples: Competition for food Competition for a mate Changes in the environment Predators Parasites

How do the 3 different types of selection affect a population over time? Three types: Directional Stabilizing Disruptive Natural selection is going to respond to how the environment shifts (or doesn’t shift) For any given trait, there will be a range of variation within the population

Directional Selection Natural selection favors one extreme of the population for that trait often happens when environment changes in a consistent way- e.g.climate gets colder.

Stabilizing Selection Natural selection favors the average for population selected Both extremes are selected against by the environment

Disruptive selection Natural selection favors both extremes selected Causes species to diverge (speciation)

Directional Selection examples Neck of Giraffe Antibiotic resistance of bacteria Moth color (melanin) Camouflage/Mimics Many sexually selected traits

Stabilizing Selection When the extremes of the trait aren’t as well suited Examples bird clutch size Elk Antlers size Giraffe neck length Tail length in birds

Disruptive Selection Causes divergence within the species Occurs when two different types of resources in one area Results in specialization for each branched group May lead to formation of new species E.g. Darwin’s Finches