Major gene reshuffling occurs during Prophase I of meiosis. This phase is crucial for genetic diversity among offspring.
During Prophase I, homologous chromosomes pair up in a process called synapsis. This pairing allows for the exchange of genetic material between chromatids of homologous chromosomes through a process known as crossing over. The points where the chromosomes exchange segments are called chiasmata.
As a result, the chromatids end up with a mix of genetic information from both parents, leading to a reshuffling of genes. This genetic variation is essential for evolution and adaptability of species. The reshuffled genes will be passed on to the gametes, thus influencing the genetic makeup of the next generation.