Calvaria major is a rare but once-abundant tree found on the island of Mauritius, which was also home to the dodo, a large flightless bird that became extinct about three centuries ago.
Topic
The decline of the Calvaria major tree on Mauritius and the debated link to the extinction of the dodo bird.
Framework
Challenge Position
Main Point
Stanley Temple proposed that the near-extinction of the Calvaria major tree was caused by the disappearance of the dodo, which he claimed was necessary for the tree’s seed germination; however, specialists have since challenged Temple’s theory, arguing that the tree can reproduce without the dodo and that other causes may better explain its rarity. (Most Valuable Sentence: The final paragraph, especially: )
P1: Introduction to Calvaria Major and Temple’s Hypothesis
We learn that Calvaria major used to be common on Mauritius, which was also home to the now-extinct dodo. Stanley Temple noted only old, dying Calvaria trees remaining and speculated that the trees stopped reproducing after the dodo disappeared.
P2: Explaining Temple’s Dodo Hypothesis
Temple suggested that the Calvaria fruit evolved a tough pit because the dodo ate the fruit, and that the dodo's process of eating and digesting the fruit was necessary to break down the pit so seeds could germinate. Without dodos, he thought, seeds were trapped and couldn’t grow.
P3: Temple’s Supporting Evidence
Temple did some indirect experiments, like feeding Calvaria pits to turkeys, and a few seeds sprouted. He used data from other birds and seed strength tests to argue that the dodo's gizzard could have done the job, using this as evidence for his theory.