A Facebook news story declares that eating chocolate increa…

 A Facebook news story declares that eating chocolate increases the risk of bladder cancers.  You click on the article and find that it cites a study where rats who consumed more chocolate had an increased risk of cancer depending on how much they consumed.  Rats who consumed the most had a high risk for bladder cancer whereas rats who did not consume chocolate had an extremely low risk of bladder cancer.  Cancer only developed after chocolate was consumed. What can you conclude from this study?

In a species of salamander, Plethodon hermani, females are m…

In a species of salamander, Plethodon hermani, females are more likely to mate with males who have red legs than males with dull legs.  Males are more likely to mate with females who have larger abdomens.  Females have evolved air sacs that they inflate to make their abdomens look bigger.   Both redness of legs and air sacs are heritable.

There are many types of Natural selection and they act on tr…

There are many types of Natural selection and they act on traits in different ways. Assume there is selection acting on size of a wing in a bird.  For each type of selection match what will happen to the variation in wing size among individuals in the population over time.  Hint: think about the distributions we drew in class for each of these types of natural selection.