The reason lies in an intraspecific battle being fought within the host species: the parasite is simply caught in the crossfire. The black-headed duck Heteronetta atricapilla, a little-known South ...

From the Galapagos Islands to New Zealand, species of birds that exist today model characteristics of their ancestors that provide clues to the environmental forces that shaped their evolution.

Now the next step: evolution. The Grants found that the offspring of the birds that survived the 1977 drought tended to be larger, with bigger beaks. So the adaptation to a changed environment led ...