The breeding of animals is necessary to produce
(4)___. Humans have bred animals and plants for
years through the process of (5)____. in order to
hand-select traits needed in the livestock or produce.
In nature, it is not quite so simple. Charles Darwin was
a naturalist that proposed the idea of (6)____ When
visiting the Galapagos islands, he discovered there was
great (7)_____ between the tortoises on different
islands. The different tortoises had specific
(8) to survive on the islands that
they were found on