Natural selection occurs to give help the best survival chance to the organisms.
If a scientist makes the argument that she has found DNA evidence that shows that evolution does not exist, the evidence would be the weak physical similarities among closely related organism and also among distantly related.
Industrial revolution produced pollution, which became the reason of black pepper moth. When time passed, they became more suitable by the process of natural selection.
hope this helps!
eukaryote is a single celled organism, so that is almost like every organism on earth (except for bacteria). so actually there are many examples
1. bananas
2. algae
3. a spider
4. a lion
5. mushroom
4. tress, grass, flowers, pines....etc
5. humans
6. cancer cells, animal cells, sperm cells, muscle cells, plant cells...etc
5. flies almost every type of fly
6. fish
so yeah you get it almost every organism is a single celled organism :D
(except for bacteria and virus)