Sequential divergence and the multiplicative origin of community diversity. 2015. PNAS.
A parasitic wasp (Diachasma alloeum) that preys upon a fruit fly species known as an apple maggot. Researchers found that the wasp evolved after the fruit flies evolved into new species when they began laying their eggs and mating on apple trees, as opposed to their native hawthorn tree hosts. Three different kinds of parasitoid wasps were collected from a number of different fly host plant environments in the wild.
Analyses in the lab showed that all three of the different kinds of wasps had diverged from others of the same kind, both genetically and with respect to host-associated physiology and behavior.
"In a sense," Smith said, "they have caught an entire community of parasitoids actively ecologically diverging in response to a historically documented host plant shift of their fly host."
From Phys Org.