How does the number of chromosomes change in speciation?
The Neo Darwinian theory of evolution indicates that the number of chromosomes must change to account for the changes in species.
The present species in the world have vastly different genetic material and number of chromosomes. If the origin of the species is one common ancestor then the number of chromosomes and genetic make up those chromosomes must change.
There is evidence that plants can change into related species by multiplying the number of chromosomes ( usually doubling)
In higher animals multiplying the number of chromosomes results in damage to the resulting organism. The doubling of the 13th chromosomes results in Down's syndrome.
An increase in the amount of information by random chance must have happened if Neo Darwinian evolution is true. However there is no experimental evidence that an increase in information can occur by random changes. Mathematics indicates that this is actually impossible.
There is evidence that the 2nd chromosome in humans is the result of the fusion of two chromosomes of a primate. This would change the number of chromosomes from 48 chromosomes in the primate to 46 chromosomes. This is evidence that speciation can occur by the loss of chromosomes but evidence that speciation can occur by the addition of chromosomes.