Let’s give a hearty welcome to guest blogger Rick. Rick will be making occasional posts to the Chawed Rosin in future. Mix it up a bit.
This is a story I heard in college, and have since repeated it many times.
Living on the island of Mauritius in the Indian Ocean, Raphus cucullatus, or the dodo, couldn’t fly, nested on the ground, and was unafraid of people due to lack of predation. Sailors, despite the dodo’s reputation for tough, stringy eating, herded them onto awaiting boats. Introduced species such as dogs, pigs, and monkeys plundered their nests. Loggers destroyed the forests. By 1681, they were extinct.
The dodo is perhaps the most famous of extinct species. It looks funny, has a funny name, and has entered the language with phrases like “dead as a dodo,” and “gone the way of the dodo.” Sort of amusing, if driving a species to extinction can be thought of as amusing. Enter the Calvaria tree!
In 1977, Stanley Temple published Plant-animal mutualism: coevolution with Dodo leads to near extinction of plant in the prestigious journal Science. It turns out the Calvaria tree has a seed coat that’s as hard as a peach pit, and won’t germinate. In 1977 there were only 13 trees left, all of them 300 or more years old. Temple speculated that the dodos would swallow the fruit, and their gizzards would abrade the seeds enough for them to sprout. As an experiment, Temple force-fed 17 seeds to turkeys, his dodo-substitutes. Seven of the seeds were crushed. Of the 10 that survived, three germinated. So laugh if you will, but the demise of the dodo lead to the near-demise of the tree that had come to depend upon it.
So that’s my dodo story. Interesting, isn’t it? Well, it seems it isn’t true. In fact, Temple’s paper has become a lesson on how not to write a paper. The Calvaria tree has no growth rings, making it difficult to determine its age, but the evidence suggests a variety of ages on Mauritius, young and old. Also, Temple’s estimate of 13 trees was inaccurate. The young trees do not have the distinctive, mangrove-like appearance of mature trees, and there were actually hundreds on the island. Temple failed to measure the abrasions the turkey gizzards inflicted on the seeds. Did the seven that failed to sprout have fewer abrasions than the three that did? Who knows? Finally, Temple made a fundamental error by not having a control. He failed to try germinating uneaten seeds. The seeds germinate without the benefit of mechanical abrasion. They sprout on their own. The basis of Temple’s hypothesis, that the Calvaria tree was dependent on the dodo for repoduction, was easily proven false.
I can’t tell you how disappointed I was to learn this. I loved this story. Short, easy to tell, easy to picture. The dodo as hero. It was perfect. All I did was google “dodo tree seed”. I just wanted to know the name of the tree, maybe refresh the memory a bit. Now I kind of wish I hadn’t.
Why did Science publish his paper? Hard to say, but perhaps the editors found the story very interesting, and were hypnotized by its appeal. It was the redemption of the dodo, and they liked it.
