Expert: Dana Krempels, Ph.D. - 1/8/2008

Question
Do you know if there is an advantage between going through heteromorphic or isomorphic alternation of generation cycles? In isomorphic cycles, the chromosome numbers are different. I think that there is a higher chance of mutations since chromosomes are different but this could be a disadvantage. For heteromorphs since the sporophyte and gametophyte are different they could probably provide protection to one another in certain environments? I'm not sure. I would greatly appreciate your help. Thanks so much.

Answer
Dear Jasmine,

Mutations may or may not be harmful, so though you could make that argument, it might not hold up to testing.

One advantage of the branching sporophyte of the higher plants is that it provides more area to have reproductive structures (rather than a single sporangium), so I'd say that the more *complex* sporophyte in the heteromorphic alternation of generations definitely offers a selective advantage simply in terms of number of spores that can be produced by the sporophyte.

Hope that helps.

Dana