In Mendelian genetics, dominant traits are first demonstrated in which generation?

In Mendelian genetics, dominant traits are first demonstrated in the F1 generation. This generation results from the crossing of two parental (P) generation individuals that possess different traits. For example, if you cross a homozygous dominant individual with a homozygous recessive individual, all offspring in the F1 generation will express the dominant trait, as they receive one allele from each parent.

This concept is pivotal in understanding Mendel’s principles of inheritance. The P generation establishes the baseline traits, but it is in the F1 generation where the dominance of the trait is visually expressed. The F2 generation can also reveal the recessive traits, but they only appear there when the F1 generation is allowed to self-cross. Therefore, the first visible expression of dominance occurs in the F1 generation.