Plants & Human Affairs (BIOL106)  -  Stephen G. Saupe, Ph.D.; Biology Department, College of St. Benedict/St. John's University, Collegeville, MN 56321; ssaupe@csbsju.edu; http://www.employees.csbsju.edu/ssaupe

Dodo's & the Tambalocoque Tree

Introduction:  In 1977, Stanley Temple published in Science magazine (the premier journal of North American science) an article entitled, "Plant-Animal Mutualism: Coevolution with Dodo Leads to Near Extinction of Plant."  Let's analyze the science underlying this article:

Background:

1. Define or describe each of the following terms.  Can you give an example of each?:

   • endemic

   • endocarp

   • mutualism

   • scarification (scarify)

   • dormancy

   • coevolution

   • frugivorous

2. Where is Mauritius?  Can you locate it on a map?

3. What is a dodo?  Search for an image and write a brief description of this bird and its natural history.

4. The common name of the tree in this study is Calvaria or tambalocoque.  What is it's scientific name according to Temple?

5. The scientific name of this tree has changed.  Why would this have occurred?

Question/Hypothesis:  Temple noted that dodos became extinct about 300 years ago and that there are few tambalocoque trees younger than 300 years.  Since he knew that the pit of the tambalocoque tree had a very hard endocarp, he speculated that the pit required passage through an animal gut in order to germinate.  This lead him to the following hypothesis:

H₁ - Passage of the pit through a dodo gut was required for the germination of tambalocoque seeds (and ultimately is responsible for the trees survival).

Evidence:  What evidence did Temple cite to support his hypothesis?  List below.

Alternate hypotheses:  There are a variety of alternate hypotheses to explain the near extinction of the trees.  List these.
 

Conclusions:  What do you conclude about Temple's hypothesis?

Flaws:

1. Why can it be said that Temple's hypothesis was NOT an "educated guess?"  (hint:  identify pertinent background research that had been published but was unknown to Temple)

2. This story can be used an example of a non-causal correlation.  Explain.

3. This story can be used an example of ignoring alternate hypotheses.  Explain.

4. Identify at least one experiment that Temple could have done to better support his hypothesis.

5. Identify at least one place that Temple failed to use a control group.

6. Temple erroneously extrapolated data from a graph.  Explain.

7. Temple made a botanical error of confusing hard seed coats with hard endocarps.  What was his mistake?

8. Temple's article was peer-reviewed and published in a prestigious journal.  What is peer-review and what do you conclude about this process?

References:

• Hershey, DA (2004) The widespread misconception that the Tambalacoque or Calvaria tree absolutely required the dodo bird for its seeds to germinate.  Plant Science Bulletin 50: 104 - 108.

• Temple, SA (1977) Plant-animal mutualism: Coevolution with dodo leads to near extinction of plant.  Science 197: 885-886.

Last updated:  09/19/2008 � Copyright  by SG Saupe