22. Evolution of Populations

The heritable differences among organisms are a result of                  . a. differences in their DNA; b. mutation; c. differences in alleles; d. A and B are correct; e. A, B, and C are correct

The risks faced by small populations include                  . a. erosion of genetic variability through genetic drift; b. decreased fitness of individuals as a result of inbreeding; c. increased risk of experiencing natural disasters; d. A and B are correct; e. A, B, and C are correct

Ivory from elephant tusks is a valuable commodity on the world market. As a result, male African elephants with large tusks have been heavily hunted for the past few centuries. Today, male elephants have significantly shorter tusks at full adulthood than male elephants in the early 1900s. This is an example of                  . a. diversifying selection; b. stabilizing selection; c. directional selection; d. chance; e. more than one of the above is correct

Antibiotic resistance is becoming common among organisms that cause a variety of human diseases. All of the following strategies help reduce the risk of antibiotic resistance evolving in a susceptible bacterial population except                  . a. using antibiotics only when appropriate, for bacterial infections that are not clearing up naturally; b. using the drugs as directed, taking all the antibiotic over the course of days prescribed; c. using more than one antibiotic at a time for difficult-to-treat organisms; d. preventing natural selection by reducing the amount of evolution the organisms can perform; e. reducing the use of antibiotics in non–health-care settings, such as agriculture

Which process ensures that alleles are always found in new combinations?

Mutations that don’t impact the fitness of an allele can be called?

Which of the following statements about mutations is correct?

Gene trees are evolutionary trees that show the evolutionary lineages of specific genes separate from organisms. Below is a gene tree for the genes that code for opsins in humans. Opsins are the light sensitive proteins in the eyes. Humans have four opsins that are active in visual perception: long-wavelength sensitive (LWS or red-sensitive), medium-wavelength sensitive (MWS or green sensitive), short-wavelength sensitive (SWS or blue sensitive), and rhodopsin (RH, not color sensitive). Which mutational process would be most likely to create a gene tree like this?

Natural selection is able to work independently on different genes that are found on the same chromosome because of which process?

Over short time periods, what would you expect to be responsible for creating the most genetic variation in humans?