Randy wrote 
> the breeders were attempting to replace a well-adapted regional stock with an introduced stock.  The authors also pointed to the example of the Africanized bee--which very successfully (and apparently lastingly) displaced the established European population in tropical America in short order.  The best adapted generally win the evolutionary competition.

Right, in Germany the effort was to establish a desirable species through conventional breeding, which essentially failed. The African bees, on the other hand, are an invasive species. These tend to be highly aggressive in populating an area, tend to usurp areas already occupied, etc. Humans mounted a huge effort to prevent African bees from becoming established, an effort which also failed. 

This example shows the difference between our effort to maintain desirable species, which is often difficult and our effort to exclude invasive ones, which is often impossible. And it shows the difference between a goal oriented human breeding strategy and evolution where success often depends on aggressively exploiting an already occupied ecosystem. 

However, other species have learned to survive and thrive by fitting in to available niches, so it isn't always a pitched battle for resources. Nature also succeeds via opportunism, chance, and luck.

PLB 

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