1. Through all forms of reproduction, what can occur that could change the function and body shape of an organism?  A DNA mutation, which occurs randomly to any part of DNA, can produce variation in the body shape and function of the organism who inherits the modified DNA.  Example given was an amoeba going through asexual reproduction mutates to have a longer arm for scavenging for food. That same trait will now be passed on to it’s future generations if it survives in nature.

2. Why can we see more variation through sexual reproduction?  Both parents contribute half of their genetic code through their sex cells. The male sperm or the female egg, both have half of the chromosomal make-up of the parent organism. So the offspring will have traits inherited by both parents.

3. What evidence do scientists use to base their conclusions of common descent upon? Fossil Record, Genetics, comparative anatomy, mathematics, biochemistry and species distribution.

4. What evidence is given to support the idea that tortoises evolved on different continents through adaptations that enabled them to thrive in their environments?  Random changes caused by descent with modification over thousands of years, eventually transformed the island creatures and the mainland creatures so much, that they could no longer be considered the same species.  Variation can be seen in the different populations of tortoises across the Galapagos Islands.  Those on the larger islands are larger and have dome shaped shells, because there is an abundance of grass here.  On the smaller islands grass is not readily available, so the tortoises adapted to eating small cactus trees. Tortoises found on these islands have adapted to have expanded front legs and a saddle like shell. This enabled them to survive here.

5. Describe the differences between natural selection and selective breeding.  Nature is a dangerous place to live in with constant competition for survival.  There are germs that can kill you, animals that can eat you. You could die from heat exhaustion. You could die of exposure to the cold.  When parents produce a variety of offspring, nature, simply by being difficult to survive in, decides which of those variations get to live and reproduce, and which do not. Over multiple generations, creatures become more and more fit for survival and reproduction within their specific environments. This is natural selection.  Selective breeding is the process by which humans breed other animals and plants for particular traits. Typically, strains that are selectively bred are domesticated, and the breeding is normally done by a professional breeder.

6. What comparative anatomy evidence is given that leads one to the idea of common descent or that all living organisms evolved from a common ancestor?

7.  Comparative anatomy: the study of differences and similarities between living things.  The anatomy of whales was used to show an example of evidence of evolution using comparative anatomy.  Whales have placentas and give live birth and feed milk to their young.  They are warm blooded!  Whales have lungs and breathe oxygen just like land mammals.  Blowholes although one hole usually at the surface, a closer inspection reveals two nasal passages leading to it.  Whales have hair on their bodies.  Also whales have similar appendages with extremely similar structure to any other mammal. No hind legs shown in whales today, but they do have a pair of strange tiny bones where this appendage would be found. These bones look like shriveled hip, thigh, and shin bones.

8. What evidence has embryology given that leads one to the idea of common descent?  Embryology: is the study of how creatures develop before being born or hatching from an egg. The video compares a dolphin embryo with a human embryo at similar stages of development.  Both at early stages show development of an arm bud and a leg bud. In humans this develops into legs, whereas in whales they eventually begin to fade away as the rest of the whale continues to grow.  The nostril grooves of a dolphin fetus at its earliest stages will be found on the front of the face. As the dolphin continues to grow these nostril groves continue to migrate toward the top of the head and fusing together to make one blowhole.

9. What evidence does the fossil record show that leads one to the idea of common descent?  The fossil record shows evidence of transitional species.  We see the nostrils move from the front of the skull towards the top.  It shows the gradual loss of limbs and hind limbs all together.

10. What comparative DNA evidence is given that leads one to the idea of common descent?

11.  Whales’ closest common living relative that shares a common ancestor is hippopotamuses.  Hippos have a specific ankle structure found in both ancient whale and hippo fossils.  Both animals give birth to and nurse their young in water.  Whales and hippos both have multi-chambered stomachs, which is extremely uncommon in carnivorous organisms.  Both have very little hair present on their bodies.  And both are the only mammals present on earth with internal testicles.