Extra Pair Copulations and Warblers
In today’s case study, we are going to read and examine pieces of a primary literature paper (Chuang-Dobbs et al. 2001) to really tease apart and understand how to identify a hypothesis and make testable predictions in behavioral ecology. We will also practice taking our verbal predictions and making them into visual prediction graphs that we can then compare with the graphs we generate with our actual data in order to evaluate our hypotheses. These are skills we are going to continue to build upon over the course of the semester, with both real-world data from published studies and our own data collected from our lab experiments.
Today’s case study looks at two behaviors in a small bird called the black-throated blue warbler. Here’s a video of the very quick mating behavior of the scrub warbler. As you watch the video, what behaviors do you see? Can you tell the difference between the males and the females? Who do you think is who? What do you think is happening?
What about the actual act of copulation? What are your thoughts on it? Take a few minutes with the video. Take some notes on the behaviors you see. Do you have any questions? We’ll meet back as a class and compare notes.
For Fun: Here’s a great resource for birds (The Cornell Lab bird site) with lots of information and videos about the black-throated blue warbler. (Links to an external site.) Did you know that males and females look so different that it was long thought they were different species?
In your small group, open up today’s case study and work together as a group to complete the assignment. We may not get all the way through the assignment today in class, but we will have a bit of time in lab today to finish it up if needed, so no need to feel rushed.
Start at the beginning and work your way through each part one at a time.
The really important part of this case study is to DRAW the prediction graphs. Because we’re doing this online I’m not going to have you submit your drawings, but do it on a piece of paper and actually draw a quick sketch of the prediction graph. It doesn’t have to be pretty with straight lines or anything. Just needs to be a general trend. This is a VERY IMPORTANT step in thinking about a prediction. SO DRAW THE GRAPHS!
Once you’ve completed the assignment you should submit the answers to the following questions which come straight from the case study.
Introduction:
- Identify the specific question(s) that authors are asking
- What is the hypothesis that they suggest?
- What predictions can you make if the hypothesis were correct?
- How can we test the predictions, i.e., what exactly might we do if we were the authors who had been studying warblers for several years?
Part 2:
6. What do you expect they might do?
7. What variables might they measure? What predictions would you make?
Part 4:
9. How do the data compare with your predictions?
10.What conclusions might the biologists make about their original hypothesis?
Introduction:
Parts 1 & 2:
Parts 3 & 4:
Citations:
Helen C. Chuang-Dobbs, Michael S. Webster, Richard T. Holmes, 201. The effectiveness of mate guarding by male black-throated blue warblers. Behavioral Ecology, 12 (5): 541–546.
