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The relationship between the relationship between crossing over and distance between two genes and distance between two genes along a chromosome was established through genetic experience notably the work of alfred sturtevant and t .h.
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Morgan and t .h.
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Morgan in the early 20th century.
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This work laid the foundation for understanding genetic linkage and genetic mapping.
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This is the step by step description of how they experimentally established this relationship.
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The first is the drosophila melanogaster experiments.
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Drosophila melanogaster.
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So this is the model organism over here.
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This was the model organism.
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Morgan and sturtevant used the fruit fly because it has a short generation time.
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It has a short generation time and large number of offsprings and well defined traits.
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Then they identified the linkage genes and selected them.
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So identification and selection of genes and selection of linked genes.
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They selected two genes for example the genes for body color.
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For body color c and the wing size v.
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Which were located on the same chromosome which was chromosome number 2 in the drosophila.
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In the next step there was generation of test process.
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So there were homozygous parental flies.
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Homozygous parental flies for such traits as they had features such as red eyes and long winged.
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Then they performed test process between the homozygous recessive and double heterozygous flies.
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And double heterozygous flies where both traits were heterozygous...