01Humans as the selective force
In artificial selection, humans choose which individuals breed. Wild mustard became broccoli, cabbage, kale and cauliflower; wolves became hundreds of dog breeds.
It works the same way as natural selection — heritable variation + differential reproduction — just with humans deciding fitness.
02Convergent evolution
Unrelated organisms under similar pressures evolve similar traits: wings in birds, bats and insects; streamlined bodies in sharks and dolphins. These are analogous structures.
03Notebook box
Artificial selection is evidence that selection on variation can produce big changes quickly.
Worked example: Why do broccoli and cabbage interbreed easily? → They're the same species, artificially selected from one ancestor.