Brazilian writer Moacyr Scliar wrote "Max and the Cats" (1981) about a Jewish youth who survives a shipwreck and shares his life boat with a panther. Yann Martel just won the Man Booker Prize for his novel, "Life of Pi," about an Indian youth who survives a shipwreck and shares his lifeboat with a tiger. Martel does say in his book that he was inspired by the earlier work by Scliar, and in the article says that he read a review of Sclair's novel but there is some mystery around his memory of it. Scliar responds in a NY Times article that "an idea is intellectual property" saying he wasn't consulted before the Pi book was published.

It's an interesting thought, and the article does cite a couple of cases where a premise was appropriated from one work for making another, where settlements were tendered. But no one has apparently read the two books to compare them, looking for more than just a similar plot. Section 102(b) of the Copyright law says, "In no case does copyright protection for an original work of authorship extend to any idea...."