Monday, April 18, 2011

What science did you do down there? (Click on the photo below for a slideshow of the field work.)

Click on the picture in this post to see a slideshow of more pictures from the field.

So as you know we had 3 different hypothesis that we were testing during our time in the field down in Florida. I want to review each of those hypothesis and let you know what we did to collect data to test each one.

#1) The Brown Anole population faces different relative selection pressures in different parts of the environment.
To test this one we put out 50 clay models in 5 locations that were carefully chosen (forest, park, residential area, beach and island) and recorded all bites in the models from predators and lizards. We only got one lizard bite but we got many predator bites. We tried putting out models with and without paper dewlaps. After the first week we moved the models to new but similar locations. We also took careful photos of the shade cover where each model was placed. A computer will analyze these photos and we will check to see if the amount of cover above a model affected how often it was attacked by predators.

#2) Morphological (physical) differences exist in the lizards in different parts of the habitat.
To test this one we planned to measure hundreds of lizards (we measured more than 800) and record careful data about the locations they were spotted in. Unfortunately this part of the project suffered a bit from our high work load. We did not have time to measure carefully the locations of each captured lizard. However, we do have careful measurements for each lizard in our island experiment so when we go back to collect lizards again we will be able to see if physical differences begin to exist on the different experimental islands.

#3 Biased Operational sex ratios will affect population growth and natural selection (evolution).
To test this hypothesis we released 835 lizards on 9 different islands. The islands were not all the same size so we released them in numbers that kept population densities (lizards per square meter) the same. On 4 of the islands we released 66.6% males and 33.3% females. On 5 other islands we did the opposite. We will be going back at the end of the summer to catch babies and record population sizes. We will take DNA samples of all the new hatchlings and compare them to the DNA of the founding populations to see which males and females are having the most reproductive success.


  1. Wow, Mr. Reedy you truly are an inspiration for all of us your students. I, at the least have learned that you don't deny yourself the chance to do something new and try everything you can. Your capability of learning new things really amazes me. For me this shows really how good of a teacher and how great of a human being you are, willing to always do what you can to show and teach your students that everything can be enjoyed as much as they want. Thank you for being a great teacher, someone to look up to.

  2. Wo Hong Wu( 3rd period)April 23, 2011 at 9:53 AM

    Mr. Reedy, you have done an excellent job! I am so proud of you. XD
    For the second hypothesis, what measurements did you do for each lizard? And can you tell it is a healthy lizard from its appearance?

  3. Wo- Thanks for your kind words! Let me answer your questions.

    The measurements that we took for each lizard were: body mass, snout to vent length, tail length, dewlap size (males only). For dewlap size we placed each male on a grid of known size, extended the dewlap with a foreceps and then photographed it. At the lab at Iowa State, Dan will then run those photos through a software that will calculate the area of each dewlap. It's not really a measurement but we also took a small tissue sample from the tip of the tail from each lizard so that we will be able to compare it to hatchlings on the island and evaluate reproductive success.

    For your second question I would say yes. We can get a good idea about the general health of a lizard by looking at it closely. You can judge if seems to be well fed and strong. Of course there could be some health problems we might not be able to detect simply by looking, but overall you can get a good idea by looking.

    Have you made a college choice yet? What will you study? Good luck with the end of your senior year.

  4. Thank you for answering my questions, Mr. Reedy.
    I just decided which college I should go couple days ago. It was very hard for me to make a decision between UC Davis and UIUC. I thought I would go to Davis (because of its pleasing weather and beautiful sceneries, plus it is a prestigious school), but then I found out its tuition is so expensive that I cannot afford it. In the end, I chose UIUC instead. The major I am going to study is civil engineering since math is the only subject I excel in.
    And thanks for your luck. I also wish you have fun with your studying.

  5. Elizabeth Tellez: Zoology: 3rd PeriodsApril 26, 2011 at 2:24 PM

    Mr. Reedy I enjoyed viewng your pictures they were great. My favorite one was of the new hatchling awaiting its brothers and/ or sisters.

  6. Mr. Reedy the shedding picture was really interesting since I've never actually seen a lizard shed their skin before...

  7. I also have never seen a red lizard before, he's pretty amazing, have you seen more than one?

  8. how long do you think DNA sampling will take if you bring some more volunteers with you to the experiment?

  9. For the first hypothesis, do you get the conclusion you want? like the effect of the paper dewlap?

  10. Glad you liked the pictures.

    Mayra- We see one or two red lizards out of every couple hundred that we catch.

    Adolfo- Collecting the DNA is quick and easy; we simply cut off the tip of the tail. Analyzing it takes more time and must be done in a lab. I am not yet sure if it will be done at Iowa State or at Harvard (or possibly somewhere else if we collaborate further).

    Yao- The data is hasn't yet been fully evaluated, but it looks like the paper dewlap did not have a significant effect on predation.

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