Questions: 2. Find a specific example of something that happens during meiosis that would change mendels expected ratio of phenotypes in the next generation. Use in text citations

During meiosis, a specific event that can alter Mendel's expected ratio of phenotypes in the next generation is "crossing over." Crossing over occurs during prophase I of meiosis when homologous chromosomes pair up and exchange segments of genetic material. This process can lead to new combinations of alleles on a chromosome, which can affect the phenotypic ratios observed in the offspring.

Mendel's expected phenotypic ratios are based on the assumption of independent assortment and no recombination between linked genes. However, if genes are located close to each other on the same chromosome, they are said to be linked and tend to be inherited together. Crossing over can break this linkage and create new allele combinations, thus altering the expected phenotypic ratios.

For example, if two genes are linked and crossing over occurs between them, the resulting gametes may have different allele combinations than expected. This can lead to a deviation from the typical 9:3:3:1 ratio observed in a dihybrid cross, as described by Mendel (Griffiths et al., 2000).

In summary, crossing over during meiosis can change Mendel's expected phenotypic ratios by creating new combinations of alleles, particularly when genes are linked on the same chromosome.

Reference: Griffiths, A. J. F., Wessler, S. R., Lewontin, R. C., & Carroll, S. B. (2000). Introduction to Genetic Analysis. W. H. Freeman.