New paper on polyploid speciation

For a long time now, people have known of speciation by the multiplication of chromosomes (polyploidy), either of one’s own chromosomes (autopolyploidy) or by doubling a mismatched set from some other species’ chromosomes (allopolyploidy) to even up the numbers and gene complements. Some have thought this to be an uninteresting and rare form of speciation (e.g., Mayr in 1942), and others that it is the main form of speciation (e.g., M. J. D. White in the 1960s and 70s). Now a paper has come out that suggests that the rate of polyploidy is between 15% and 30% in plants. Neither the primary mode, nor the uninteresting aberrations of Mayr. The EBB and Flow has a review of this paper here.

How does this translate to other organisms like animals? It is going to depend on two factors, one generic and one specific. The generic is whether or not the species is a gamete broadcaster – whether it simply disperses spores into a medium like water or air. A coral specialist once told me that what maintains coral species, for example, is the prevailing currents; as they change, so too do the fertilisation events. The specific is whether or not the meiosis process (i.e., the halving of the chromosome count in gamete formation) is easily disrupted in that species, or whether chromosomes can easily be doubled and then not reduced in the zygote.

In other words, we don’t know for sure. But I will bet that it is less than 30% for animals, but more than 0%.