[Wacka]

Most crop plants are polyploid (have multiples of their original numbers of chromosomes).
From Wickipedia:
* Triploid crops: banana, apple, ginger, watermelon, citrus
* Tetraploid crops: durum or macaroni wheat, maize, cotton, potato, cabbage, leek, tobacco, peanut, kinnow, Pelargonium
* Hexaploid crops: chrysanthemum, bread wheat, triticale, oat, kiwifruit
* Octaploid crops: strawberry, dahlia, pansies, sugar cane

Some crops are found in a variety of ploidy. Apples, tulips and lilies are commonly found as both diploid and as triploid. Daylilies (Hemerocallis) cultivars are available as either diploid or tetraploid. Kinnows can be tetraploid, diploid, or triploid.

[metmom]

What about animals? And people for example?

I’ve yet to find any information that indicates that a change in the number of chromosomes produces or ever has produced a beneficial change. At best, it might be neutral, if there are other factors involved.

http://ghr.nlm.nih.gov/handbook/mutationsanddisorders/chromosomalconditions
http://www.genetics.com.au/pdf/factsheets/fs06.pdf

Are you saying then that this is the case only for humans? That it is not representative across the board in the animal kingdom? Do changes in the number of chromosomes have no effect or a beneficial one in animals only but not humans?

Examples please.