Variation of Species
Variation is the natural difference between living things. Animals and plants that are produced by sexual reproduction always vary from their relatives. This is because each one has its own unique collection of genes. Variation is important because it enables a species to change slowly through the process of evolution. A population of living things has three sources of variation: • Immigration of individuals with new genes into a population. • Recombination of genes during meiosis • Mutation.
Varieties of finches
While visiting the Galapagos Islands in 1835, Charles Darwin was puzzled to find different species of finch on each island. He struggled to explain why these differences might exist. Of all the animals he observed, it was the finches that had the deepest influence on his thinking. Each species of finch had a unique beak.
1. 2.
How do you think the different beak type enables each finch to be best suited to its food source? What time frame do you think would have been involved in the evolution of the different beak types?
3. Look at the beak of the ancestral finch. To what type of food do you think it is suited?
