The evolution of new species | Exit Quiz | Oak National Academy

True or false? The theory of evolution by natural selection suggests that all modern species evolved from earlier species.

• True

• False

Answer explanation

Using a variety of evidence including fossils, DNA and field observations we can map how species are related and find common ancestors that lived many years ago.

When natural selection causes a new species to form we say ___ has taken place?

Answer explanation

Sometimes, the features of a group of organisms can change so much that we classify them as a new species. This is speciation.

Which of the following is why some Galápagos tortoises have saddle-shaped shells?

• Some tortoises stretched up to get food and stretched their shells.

• The shape of tortoises’ shells has no relationship to the food they eat.

• They were more likely to survive as they could reach more food.

• Some tortoises stretched up to get food and passed this onto their offspring.

Answer explanation

In any population there is variation, those tortoises with more saddle-shaped shells are able to access more food. When organisms have enough food they will breed and pass on that characteristic. Over time the characteristic will become more common.

True or false? DNA can be used to help establish relationships between organisms.

• True

• Fasle

Answer explanation

True. We can look at the DNA of different species to see how related they are.

Put these in order to show the process of speciation.

• The populations, unable to mate with each other, become reproductively isolated.

• Different conditions in areas cause different traits to become more common.

• Populations of the same species become geographically separated.

• Populations are so different from each other they can no longer interbreed.

Answer explanation

Once populations can no longer interbreed and produce fertile offspring they are said to be a new species.

Which of the following is not a geographical barrier that mean species can become isolated?

• Trees

• Seas

• Rivers

• Mountains

• Deserts

Answer explanation

To isolate a population the barriers are usually very big such as mountains, seas and rivers.