TF: Pan Pan Jiang
THE O RIGIN OF THE SPECIES:C HAPTER 1 (VARIATION U NDER D OMESTICATION )
What wasDarwin’stheory of inheritance? (What“causesvariation”)?
Darwin postulates that variation originates with male and female reproductive elements being
affected in some unknown way before offspring are produced. He then suggests that most variation is
heritable, with the idea of “like producing like” clearly exhibited by breeders. He also uses the
example of rare traits such as albinism appearing in a child of an affected parent as evidence for the
high probability that all types of variation are heritable. “Perhaps the correct way of viewing the whole
subject, would be, to look at the inheritance of every character whatever as the rule, and non-
inheritance as the anomaly.”
Darwinspendsasignificant proportionof Chapter1 discussing pigeons. What observations from domestic
species does heusetobuild an argument for evolutionbynatural selection?Explain.
Darwin first refutes the alternative hypothesis that existing pigeon v