Question

Explain how Seely’s experimental system (Flat Periwinkles and Green Crabs), as currently described in Darwin’s four postulates. You must address each postulate separately. If you feel that one or more of the postulates was not met, please indicate which one(s).

Answer 1

For the first postulate, “Individuals within a species are variable” Seely observes that L btusata and C. maenas have different thickness of shells.

For the second postulate about heritability – that also occurs in offspring of speicies.

For the third postulate about natural selection, the absence of C. maenas in West coast but presence of C. maenas in East coast suggests about the natural selection phenomenon in shell thickness.

For the fourth postulate, about “reproduction” has also evidence that shell thickness supports production and survivability of species. L btusata do not survive and reproduce efficiently in presence of C. maenas, because C. maenas have thick shell while L btusata do not have; their shells get break easily by C. maenas.