Briefly mention the contribution of TH Morgan in genetics.
TH Morgan's contribution in genetics are
(i) Morgan contributed to the understanding of sex-linked traits.
(ii) He carried out several experiments on fruit flies and his dihybrid crosses revealed that genes for some traits did not segregate independently and the F2 ratio was a lot different from 9 : 3 : 3 : 1(expected when two genes are independent).
(iii) He inferred that when two genes were situated on the same chromosome, the proportions of parental gene combinations were significantly higher than the non-parental type.
(iv) He established the principle of linkage crossing over, sex-linked inheritance and discovered the relation.
(v) He established the technique of chromosome mapping.
(iv) He observed and worked on mutation.