Final answer:
New sex determining chromosomes can arise through genetic mutations and genomic rearrangements, such as the addition or deletion of genes on existing sex chromosomes or the translocation of sex determining genes from autosomes to sex chromosomes.
Step-by-step explanation:
New sex determining chromosomes can arise through various mechanisms, such as genetic mutations and genomic rearrangements. One way is through the addition or deletion of genes on the existing sex chromosomes, which can result in the formation of new sex determining regions. For example, in some species of fish, there are three sex chromosomes instead of the usual two. Another mechanism is the translocation of sex determining genes from autosomes (non-sex chromosomes) to the sex chromosomes. This can occur through chromosomal rearrangements and can lead to the evolution of new sex determining chromosomes.