CINS 2 4. In the finch population, what are the primary changes that occur gradually over time? The traits of each finch within a population gradually change. The proportions of finches having different traits within a population change. Successful behaviors learned by finches are passed on to offspring. Mutations occur to meet the needs of the finches as the environment changes. 5. Depending on beak size and shape, some finches get nectar from flowers, some eat grubs from bark, some eat small seeds, and some eat large nuts. Which statement best describes the interactions among the finches and the food supply? Most of the finches on an island cooperate to find food and what they find. Many of the finches on an island fight with one another and the physically strongest ones win. There is more than enough food to meet all the finches’ needs so they don’t need to compete for food. Finches compete primarily with closely related finches that eat the same kinds of food, and some may die from lack of food. 6. How did the different beak first arise in the Galapagos finches? The changes in the finches’ beak size and shape occurred because of their need to be able to eat different kinds of food to survive. Changes in the finches’ beaks occurred by chance, and when there was a good match between beak structure and available food, those birds had more offspring. The changes in the finches’ beaks occurred because the environment induced the desired genetic changes. The finches’ beaks changed a little bit in size and shape with each successive generation, some getting larger and some getting smaller. 7. What type of variation in finches is passed to the offspring? Any behaviors that were learned during a finch’s lifetime. Only characteristics that were beneficial during a finch’s lifetime. All characteristics that were genetically determined. Any characteristics that were positively influenced by the environment during a finch’s lifetime. 8. What caused populations of birds having different beak shapes and sizes to become distinct species distributed on the various islands? The finches were quite variable, and those whose features were best suited to the available food supply on each island reproduced most successfully. All finches are essentially alike and there are not really fourteen different species.
Age at death 4 years 5 years 4 years 6 Comments Lizard A is very healthy, strong, and clever Lizard B has mated with many lizards Lizard C is dark- colored and very quick Lizard D has the largest territory of all the lizards Lizard A Lizard B Lizard C Lizard D 19. According to the theory of natural selection, where did the variations in body size in the three species of lizards most likely come from? The lizards needed to change in order to survive, so beneficial new traits developed. The lizards wanted to become different in size, so beneficial new traits gradually appeared in the population. Random genetic changes and sexual recombination both created new variations. The island environment caused genetic changes in the lizards. 20. What could cause one species to change into three species over time? Groups of lizards encountered different island environments so the lizards needed to become new species with different traits in order to survive. Groups of lizards must have been geographically isolated from other groups and random genetic changes must have accumulated in these lizard populations over time. There may be minor variations, but all lizards are essentially alike and all are members of a single species. In order to survive, different groups of lizards needed to adapt to the different islands, and so all organisms in each group gradually evolved to become a new lizard species.