Why is there similarities in life forms found in the same type of biome in separated areas?

Question

Why is there similarities in life forms found in the same type of biome in separated areas?

Answer 1

Because the adaptive pressures are similar, so any adaptations which give selective advantage would be similar. Convergent evolution.

Answer 2

An example of this are cactus and succulants. They both developed in geographicaly different areas from different genetic backgrounds. The thing they have in common are that they both live in arid and hot conditions and need to conserve water. This is called converging evolution.