What does non-disjunction during meiosis result in?

Non-disjunction during meiosis results in the uneven distribution of chromosomes among the gametes. This process occurs when homologous chromosomes or sister chromatids fail to separate properly during cell division. As a result, some gametes may end up with an extra chromosome (trisomy) or lacking a chromosome (monosomy). This chromosomal imbalance can lead to various genetic disorders or developmental issues in the resulting offspring, depending on which chromosomes are involved.

The other options do not accurately describe the effects of non-disjunction. The separation of sister chromatids is a normal and expected event during meiosis and does not relate to non-disjunction. The formation of identical gametes is generally associated with mitosis, not meiosis, where genetic diversity through recombination occurs. Lastly, reproductive isolation pertains to the mechanisms that prevent species from interbreeding and is not directly related to non-disjunction or chromosomal abnormalities.