Exam 2 - Discussion Questions
Why was the demonstration of human resistance to malaria important to evolutionary biology?
"evolution in action"; agent of natural selection still known and active; measurable; well documented; also showed that gene mutation that might be bad in one scenario are good in another; finally shows that evolution works with what is available in the struggle for survival;
What is a fossil gene?
a gene that is still present but that does not perform any function
What resemblances do you see between the fossil coelacanth and the fish sketched by Marjorie Courtenay-Latimer in Figure 7.2?
body shape; number of fins;
How did fish antifreeze originate?
found near Bouvet; evolved based on the cold/stable temperatures in Antarctic in food and oxygen rich waters; trypsinogen gene came from; now have antifreeze glycoproteins (AFGPs) to keep them from freezing;
"Living fossil" is a term that has been informally used to describe crocodiles, horseshoe crabs, ginkgo trees, and some other plants and animals. Are living members of these groups exceptionally long-lived species? How does the term "living fossil" apply to the coelacanth?
living fossil indicates that the species descended from a series of ancestors extending back; the coelacanth closely resembled extinct relatives especially it's limb-like fins
How do icefish obtain their oxygen? What might happen to icefish if the waters around the Antarctic became warmer?
lower viscosity of blood; large gills; scaleless skin with large capillaries; larger hearts; larger volume of blood; now that the icefish have adapted to the cold environment, they would not survive a warmer environment; it would take generations for another evolution to survive in a different environment
It is sometimes said that the Earth and life evolve together. How does the history of icefish support this statement?
organisms adapt as best they can to a changing world; it is a bit of a moving target rather than a defined goal; changes occur over a long period and during that time the Earth is changing as well;
What makes the sickle-cell mutation a balanced polymorphism?
polymorphism means the heterozygote has an advantage over either homozygote; for sickle-cell the heterozygote has the resistance to malaria
How did Tony Allison's early life experiences in Kenya prepare him to make the discovery of the sickle cell - malaria link?
raised in Kenya; father encouraged interest in natural history; went on birding safaris; was a field assistant and interested in archeological opportunities; impressed by Darwin; in medical school became interested in genetics;
What is the significance of the structure of the coelacanth pectoral and pelvic fins?
these lobed fins evolved into the walking limbs of land vertebrates; fins attach by a single bone and are in the same position as the humerus and femur of four legged animals; this allows for greater rotation of limbs; it is also interesting that they move in an alternating fashion - the right front with the left rear and the left front with the right rear like four legged animals walk.
