Chapter 17

Individuals don't evolve ______ do.

Biologists define evolution as ______ a. purposeful change in a lineage b. heritable change in a line of descent c. acquiring traits during the individual's lifetime

______ is the original source of new alleles. a. Mutation b. Natural selection c. Genetic drift d. Gene flow e. All are original sources of new alleles

Natural selection can only occur in a population when there are ______ a. differences in forms of heritable traits b. different selection pressures c. both a and b

Directional selection ______ a. eliminates common forms of alleles b. shifts allele frequencies in one direction only c. does not favor intermediate forms of a trait d. works against adaptive traits

Disruptive selection ______ a. eliminates uncommon forms of alleles b. shifts allele frequencies in one direction only c. does not favor intermediate forms of a trait d. both b and \(c\)

Sexual selection, such as competition between males for access to fertile females, frequently influences aspects of body form and leads to ______ a. violence b. sexual behavior c. sexual dimorphism d. both b and

The persistence of malaria and sickle-cell anemia in a population is a case of ______ a. bottlenecking b. balanced polymorphism c. natural selection d. artificial selection e. both b and \(c\)

______ tends to keep populations similar to one another. a. Genetic drift b. Gene flow c. Mutation d. Natural selection

Match the evolution concepts. $$ \text {gene flow} \quad \quad\quad\quad\quad \text {a. source of new alleles} $$ $$ \text {natural selection} \quad \quad\quad\quad\quad \text {b. changes in a population's allele frequencies due to chance alone} $$ $$ \text {mutation} \quad \quad\quad\quad\quad \text {c. allele frequencies change owing to immigration, emigration, or both} $$ $$ \text { genetic drift } \quad \quad\quad\quad\quad \text {d. survival of the fittest} $$ $$ \text {adaptive radiation} \quad \quad\quad\quad\quad \text {e. burst of divergences from one lineage into a set of niches } $$