Wilhelm Johannsen (3 February 1857 – 11 November 1927) was a Danish botanist, plant physiologist and geneticist. His most well-known research concerned so-called pure lines of the self-fertile common bean. He was able to show that even in populations homozygous for all traits, i.e. without genetic variation, seed size followed a normal distribution. This was attributable to resource provision to the mother plant and to the position of seeds in pods and of pods on the plant. This led him to coin the terms phenotype and genotype.
His findings led him to oppose contemporary Darwinists, most notably Francis Galton and Karl Pearson, who held the occurrence of normal distributed trait variation in populations as proof of gradual genetic variation on which selection could act. Only with the modern evolutionary synthesis, was it established that variation needed to be heritable to act as the raw material for selection. The terms phenotype and genotype were created by Wilhelm Johannsen. Johannsen introduced the term gene as well. This term was coined in opposition to the then common pangene that stemmed from Darwin’s theory of pangenesis.
One of the founders of Genetics as a science! His classical experiment with bean size has been ever since the introductory lecture for quantitative genetics.
Info taken from wikipedia: http://en.wikipedia.org/wiki/Wilhelm_Johannsen