polyploidy

[rasing02]

polyploidy is more common in plants as compared to animals, why?

[cypress]

The simple answer is that the extra chromosomes seems more often to not harm plant cell function and often improves plant development whereas in animals it is more commonly dysfunctional and most occurrences in animals (most often due to polyspermy) result in premature death.

[rasing02]

Thanks for your response. Why are plants tolerant towards this occurence, while it proves lethal in animals.

[cypress]

I don't know. It seems that it is more than the inefficiency of redundancy. It must impact development somehow, perhaps due to overexpression of developmental control genes. Evidence for this is that polyploidy animals begin to develop but most often don't reach maturity. Animals seem to have more complex developmental controls that may be more sensitive to imbalances caused by excess chromosomes, whereas plant cells generally have relatively more genes and fewer non-protein encoding controls which may be a factor.

 

I am making guesses here, so if anybody has better information,please bail me out. In the mean time I will see if I can find something more about this.

[rasing02]

thanks a ton

[pedore]

I'm not positive about this, but I think it also has something to do with the higher rate of asexual reproduction in plants. Accidental polyploidy in an animal species is likely to render that individual infertile, and unless the animal is capable of reproducing through parthenogenesis, they will not be able to pass the polyploid condition on to any offspring. Plants are more likely to be able to create 'clones' through budding, fragmentation, or other types of asexual reproduction, and so more polyploid individuals may be created. This might allow the plant in question to undergo other processes that could make it fertile again (chromosomal rearrangements of some sort).

 

Of course, this doesn't begin to cover the fact that Cypress brought up - that polyploid animals are formed but usually do not survive to maturity. So obviously there is more to it than that, but I thought I'd throw it out there.