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Terms in this set (16)

On his voyage, he observed certain characteristics of species across the islands that differed, and they only made sense when considered in relation to the environment.

- Finches varied by beak size/shape across the islands. This was because they each had the best beak in relation to the type of food commonly found on that island. They had sharp beaks if they had to pierce thick skin of plants, small and skinny beaks to eat insects, or large beaks to eat nuts. As he observed the islands, he found that the beak characteristics were directly related to the food that was common in the area.

- Tortoises varied by shell shape across the islands as well. Some had shells with a soft curve, and these generally lived where food was low to the ground. Others had shells with a curve much higher, allowing for the neck to be stretched further up. These lived where the food was higher up.

- The Blue-footed boobie had blue feet. This is quite an unusual characteristic for a bird, yet it makes sense in relation to the environment because they spend a lot of time standing in the water, and their blue feet would help them camouflage so that they had an easier time getting food from the water.

All of those species had the characteristics that made them best equipt to survive in the specific environment that they lived in.

This could be explained as natural selection because the ones without this advantageous trait would have had a harder time surviving, and therefore had a lower chance of living long enough to reproduce and pass their traits down to the next generation, while the ones with the advantage would have higher chances of passing on that trait to their offspring. This changes the gene pool by changing the frequency of alleles, making the majority of the population possess that allele linked to the advantageous trait.

He also noticed that fossils resembled living creatures found in the Galapagos. This proved that they originated from a common ancestor because phenotypic similarities are a result of similar DNA.