Chromosomal Theory of Inheritance
Mendel's pioneering work on inheritance, although published in 1865, went largely unrecognized until 1900 because of communication barriers, skepticism about his concepts of discrete factors (later termed genes), and the innovative statistical methods he employed, which were unusual for biologists of his time. His theory did not gain traction partly because he could not provide physical evidence for the existence of these factors.
In 1900, the re-discovery of Mendel's principles by scientists such as de Vries, Correns, and von Tschermak coincided with advancements in microscopy, revealing structures known as chromosomes within the nucleus of cells. This development led to the understanding that chromosomes behaved as Mendel described genes. Sutton and Boveri demonstrated parallels between the behavior of chromosomes during cell division and the segregation and assortment of Mendelian factors, culminating in the Chromosomal Theory of Inheritance.
This theory posits that chromosomes occur in pairs and segregate independently during the formation of gametes, mirroring the behavior of genes. This was a significant step forward in genetics as it provided a physical basis for Mendel's laws, establishing that each gene occupies a specific location on a chromosome. Further experimental work by scientists such as Thomas Hunt Morgan involving the fruit fly, Drosophila melanogaster, provided empirical evidence supporting chromosome behavior in relation to gene linkage and recombination, reinforcing the framework of modern genetics.