Dobzhansky

Dr. Ayala moved to New York for studies at Columbia University, receiving his master’s degree in 1963 and doctorate in 1964 under the mentorship of Theodosius Dobzhansky, a pioneering geneticist.

When Dobzhansky harvested the two cages after four months, he found that the populations had changed dramatically.

To explain the intersection of genetics, natural selection, and evolution in formal terms, Dobzhansky resurrected two important words—genotype and phenotype.

Dobzhansky could now restate the essential truth of Mendel’s discovery—a gene determines a physical feature—by generalizing that idea across multiple genes and multiple features: a genotype determines a phenotype.

First, Dobzhansky noted, genotypes were not the sole determinants of phenotypes.