Dominant vs. recessive traits, the 3:1 phenotypic ratio in the F2 generation, and independent assortment.

Correns cited Mendel’s original work; de Vries did not.

Evidence suggests he was likely familiar with Mendel’s work before his 1900 publication.

Mendel first used allele notation, later clarified by Correns.

Correns.

Correns.

Walter Sutton and Theodor Boveri.

Chromosomes occur in pairs, segregate during meiosis, gametes receive one chromosome from each pair, and random alignment explains independent assortment.

All chromosomes are required for development, sperm and egg contribute equally, and chromosomes carry inheritance information.

Dominant alleles mask recessive alleles in heterozygotes.

Organisms carry two alleles per gene which separate during gamete formation.

Each gamete has a 50% chance of receiving the dominant allele.

Homologous chromosomes segregate during meiosis I.

Correns.

Chromosome pairs align independently during metaphase I.

Because independent assortment reflects chromosome behavior.

de Vries’ mutation theory.

All offspring show the dominant phenotype.

Sex determined by X and Y chromosomes.

White eyes appeared primarily in males.

2 red-eyed females : 1 red-eyed male : 1 white-eyed male.

1 red-eyed female : 1 white-eyed male.

Only parental combinations appear (no recombinants).

Because linked genes should assort dependently.

1:1 parental phenotypes.

1:1:1:1.

Linkage with occasional recombination.

Crossing over during meiosis.

Homologous chromosomes exchange segments in prophase I.

His genes were on different chromosomes.

Observed pink flowers from red × white crosses.

Blended phenotypic expression.

Traits controlled by multiple genes producing continuous variation.