Final answer:
Tandem duplications can result in additional copies of a gene or region through mechanisms like unequal crossing over during meiosis, errors by DNA polymerase during DNA replication, or replication fork stalling and template switching.
Step-by-step explanation:
Tandem duplications can produce even more copies of the duplicated region through a process known as unequal crossing over during meiosis.
This occurs when homologous chromosomes misalign during recombination, resulting in one chromosome with extra copies of certain genes (duplication) and the other with fewer copies (deletion).
Homologous recombination can also lead to tandem duplications if it occurs between misaligned repeats within a single chromosome.
This is sometimes facilitated by sequences known as replication slippage or DNA polymerase errors during DNA replication.
A mechanism that can specifically cause the increase of a duplicated region is known as a replication fork stalling and template switching (FoSTeS) or microhomology-mediated break-induced replication (MMBIR), which can result in complex genomic rearrangements including tandem duplications.