What is the importance of "cross-over" during meiosis?

During cross-over segments of DNA are exchanged between the pairs of logous chromosomes. Once they separate and gametes are formed, every daughter chromosome is different from the parental ones and carries a new combination of alleles. This is how genetic diversity is generated and is the basis of ual reproduction. It is the genetic diversity between individuals that allows natural selection to operate and ultimately drives the adaptation of species to their environments.