The fruit fly Drosophila subobscura has been evolving bigger wings in higher latitudes in North and South America;
Actually it is still a fruit fly.
The decline in head size of Australian frog-eating snakes in response to the arrival of poisonous toads in 1935 (a smaller head makes it harder to eat a deadly toad).
It is still a frog.
Insect pests evolving resistance to pesticides
Actually, all the information was there already, the situation brought out the defense. Just like you have anti-virus fighting machines in your body. When a threat arises those fighters go to work, even though you wouldn’t recognize it at first.
Antibiotic resistance in bacteria
I’m guessing you are probably referring to the time when bacteria that had their “lactose-break-down” genes removed were fed lactose. Amazingly these bacteria broke down the lactose. However, later the bacteria were exposed because of a gene called ebg genes that breaks down lactose. When the experiment was done again without the ebg genes the bacteria died.