To get from a non-flying creature to a bird hypothetically - ( I could have chosen flying insects too but I am sure there are absoultely no fossils that could even suggest insect evolution)
I'm married to an entomologist and believe me when I tell you, I don't know where you got that idea. There's a huge fossil record for insect evolution. They fossilize great because of their sclerized exoskeleton.
What on Earth leads you to "be sure" that insect fossils don't show a very clear pattern of insect development?
Suppose that a bacterium recieves a mutation that confers resistance to an antibiotic that is not present in the envrionment. Beneficial or neutral?
Suppose further that the mutation causes resistance by changing a gene product that allows the bacterium to metabolize lactose when glucose is not present. The protein no longer has that function but now promotes resistance against the antibiotic. Neither lactose nor the antibiotic are present in the environment, and glucose is present. Beneficial, neutral, or harmful?
The antibiotic is present, but lactose is not. Beneficial, neutral, or harmful?
Lactose is present, but the antibiotic is not. Beneficial, neutral, or harmful?
Both lactose and the antibiotic are present. Beneficial, neutral, or harmful?
A new antibiotic is introduced that specifically targets the mutation. Wild-type bacteria are not affected. Beneficial, neutral, or harmful?