Another condition necessary for natural selection to occur is that progeny must differ from each other in their types of alleles. Do you think this is true for most plants or animals? Be careful for some familiar crop plants. Bananas have no seeds. They must be propagated by taking cuttings from buds at the base of the plant. All of the bananas in a store are clones— they are all the same plant. Can natural selection affect these bananas? Most apple varieties are also clones. Are they being affected by natural selection?