What process involves the exchange of portions of chromatids during meiosis?

The process that involves the exchange of portions of chromatids during meiosis is known as crossing-over. This occurs during prophase I of meiosis, where homologous chromosomes pair up and exchange segments of their genetic material. This exchange enhances genetic diversity by producing new combinations of alleles, which are then passed on to the resulting gametes.

Crossing-over is essential for sexual reproduction and contributes to the variation observed in populations. The increased genetic variation allows for a greater adaptability to changing environments, which is crucial for evolution and the survival of species.

While segregation refers to the separation of homologous chromosomes during anaphase I of meiosis, and replication pertains to the duplication of DNA before cell division, these processes do not involve the exchange of segments between chromatids. Therefore, crossing-over is the accurate term that specifically describes the exchange that takes place between chromatids during meiosis.