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There are very few animals with polyploidy like salamanders. Why is it that polyploidy is so uncommon in animals? On the other hand there are numerous examples of polyploid plants. If ut something to do with the gene dosage, how does it not affect plants?

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Polyploidy is common in plants than in animals because in animals sex determination mechanism involves number and type sex chromosomes. Polyploidy will interfere with this mechanism and hence it is seen rarely in animals. I believe its probably because an animal progeny with multiple sex chromosomes won't be able to reproduce more of its kind unless it can also reproduce asexually (which is seen in plants as mentioned below).

Plants, on the other hand do not have any such sex determination (based on number or type of chromosomes) and majority of them can also reproduce vegetatively. This vegetative propagation enables multiplication of polyploid plants. Sexual reproduction will result in loss of desired polyploidy as per the principle of segregation. However, if a polyploid plant can produce a viable progeny sexually, it might have a different ploidy than its polyploid parent which won't happen if the parent reproduces asexually. Hence, polyploid plants can be classified as sterile and fertile polyploids (the reference will give a detailed account on this mechanism).

Refer the section of Polyploidy (page 115, Chapter 6) of this book (Principles of Genetics, Snustad and Simons, 6th edition)

When it comes to gene dosage, animals do show gene compensation of X-linked genes by various methods. Example- formation of Barr Body in human females (Note that this has nothing to do with polyploidy, but happens since females have one X chromosome more than males). Whereas gene dosage in polyploid palnts has been exploited for improved agricultural yields as they have shown better productivity than their diploid couterparts.

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  • $\begingroup$ Are there really more asexually reproducing plants than asexually reproducing animals? Can you back up the claim with a reference? Also, sex does not involve gender and gender does not involve sex chromosomes. Intuitively, I would think of the absence of gene dosage in plants (assuming this is true, reference would be needed) as preventing events of ploidy change, so your hypothesis is unclear to me. $\endgroup$ – Remi.b Nov 7 '16 at 6:32
  • $\begingroup$ Polyploid plants including rice and wheat can reproduce sexually. $\endgroup$ – Always Confused Nov 7 '16 at 10:29
  • $\begingroup$ @Remi.b I have tried explaining that why I think the sex determination mechanism has a role in this. I suggest to go through the reference once. It's really helpful and elaborate. $\endgroup$ – Ramil Nov 9 '16 at 10:12
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    $\begingroup$ @AlwaysConfused Yes, you are right. These polyploids fall in the category of fertile polyploids. The reference gives an account on their propagation. $\endgroup$ – Ramil Nov 9 '16 at 10:24
  • $\begingroup$ @ downvoters please explain why it is wrong/unclear/inadequate research-effort/doesn't contain reference or citation. $\endgroup$ – Always Confused Nov 11 '16 at 3:38

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