The content you've requested is available without charge only to active Sigma Xi members and American Scientist subscribers.
If you are an active member or an individual subscriber, please log in now in order to access this article.
If you are not a member or individual subscriber, you can:
The finches of the Galapagos Islands provide a classic example of adaptive radiation—the evolutionary process through which a single lineage gives rise to species occupying diverse environmental niches. In one model of how species form, geographical separation leads to evolutionary divergence. Recent evidence permits refinement of this model. For one thing, the relationships among Darwin's finches have become clearer through studies of DNA sequence variation. Also, it is now clear that the Galapagos Islands have changed radically over the 3 million years during which the finches have evolved; changes in the character of the archipelago have helped drive the radiation of species. The birds? physical appearance and song appear to act as cues that help isolate populations when mating. Though it is not yet possible to thoroughly recount how Darwin's finches have evolved, an increasingly dynamic view of adaptation offers an improved explanation.
Connect With Us:
An early peek at each new issue, with descriptions of feature articles, columns, and more. Every other issue contains links to everything in the latest issue's table of contents.News of book reviews published in American Scientist and around the web, as well as other noteworthy happenings in the world of science books.
To sign up for automatic emails of the American Scientist Update and Scientists' Nightstand issues, create an online profile, then sign up in the My AmSci area.
JSTOR, the online academic archive, contains complete back issues of American Scientist from 1913 (known then as the Sigma Xi Quarterly) through 2005.
The table of contents for each issue is freely available to all users; those with institutional access can read each complete issue.
View the full collection here.
Receive notification when new content is posted from the entire website, or choose from the customized feeds available.