The Dodo and Calvaria major
I found the following bit in an article entitled, "Islands: Crucibles of
Evolution," by Robert I. Bowman, professor emeritus at San Francisco State
University.
"The close correlation among organisms in an ecosystem is well
illustrated by an example from Mauritius, once the home of the extinct
dodo, Raphus cuculatus, an aberrant, flightless relative of pigeons
about the size of a turkey, and a ready source of fresh meat for early
colonists. The eminent ecologist Stanley A. Temple of the University of
Wisconsin was perplexed by the lack of natural reproduction in the
endemic tree Calvaria major, formerly widespread on the island. His
studies of historical records suggested that the dodo fed on the large
fleshy fruit which contained a hard pit that fails to germinate if not
mechanically abraded, presumably by the gravel-gorged gizzard of the
dodo. With the loss of this cooperative relationship, termed mutualism,
the tree fails to reproduce. The last surviving Calvaria trees are of an
age that matches the time when the dodo became extinct, about three
hundred years ago.
Calvaria seeds were recently fed to domestic turkeys, which have
digestive mechanics similar to dodos, and some of the defecated seeds
did germinate. After the extinction of the dodo, apparently no other
Mauritian animal was capable of ingesting and scarring the large
Calvaria pits. For three centuries the tree had failed to reproduce and
was on the verge of extinction. Rescue efforts by nursery technicians of
the Mauritian Forestry have been successful. "
