Gregor Mendel's observation on hybridization in Pisum
Mendel
took as his parental lines
(P)
two pure-breeding lines of garden
peas
(Pisum sativum) that
differed
in a single
character (coat
colour), which
existed in one or the other of two phenotypes
(yellow or green). When the two
lines were artificially crossed, the offspring were invariably
yellow.
When these first filial
generation
(F1) plants were crossed, seeds of
both
colours were observed in the F2 generation. Mendel's scientific
insight
was to count
the relative proportions of the two phenotypes: he found that they always
occurred in a 3:1 ratio, with the F1 phenotype predominating.