Ch. 23

Question 1

What is relative fitness?

Answer 1

Passing more genes to the next generation, relative to other individuals
- If pass on more genes to the next generation then you are more likely to fit than the individuals in your population
The contribution an individual makes to the gene pool of the next generation relative to the contributions of other individuals

Question 2

Certain traits can lead to greater _______________

Answer 2

Relative fitness

Question 3

What is a prerequisite for evolution?

Answer 3

Variation in heritable traits

Question 4

What is a gene pool?

Answer 4

Collection of all genes in a population

Question 5

What is a population?

Answer 5

Is a group of individuals of the same species that live in the same area and interbreed, producing fertile offspring

Question 6

What is evolution?

Answer 6

Changes in gene pool of population overtime

Question 7

What is genetic drift?

Answer 7

Random or chance events that change gene pool

Question 8

What is genetic flow?

Answer 8

Genes moving into or out of populations (via migration)

Question 9

Only ________ consistently leads to organisms being more adapted to their environment

Answer 9

Natural selection

Question 10

Micro evolution is what?

Answer 10

Small changes to gene pool overtime

Question 11

What alters occurrence and distribution of heritable traits?

Answer 11

natural selection
- directional selection
- stabilizing selection
- disruptive selection

Question 12

What are the 3 modes of natural selection that alter distribution of heritable trains in a population

Answer 12

• directional selection
• stabilizing selection
• disruptive selection

Question 13

What is directional selection?

Answer 13

Natural selection in which individuals at one end of the phenotypic range survive or reproduce more successfully than other individuals
- shifts a pop. Frequency curve for the phenotypic character in one direction or the other

Question 14

What is the common cause to directional selection?

Answer 14

Common when a populations environment changes or when members of a populations environment changes or when members of a population migrate to a new/different habitat

Question 15

What is an example of directional selection?

Answer 15

Abundance of large seeds over small seeds led to an increase in black depth in a population of Galapagos finches

Question 16

What is Stabilizing selection? Give an example.

Answer 16

Acts against extreme phenotypes and favors immediate variants
- it reduces variation
Ex: babies that are smaller suffer higher rates of mortality; Babies who are much larger show a slight increase in mortality

Question 17

What is disruptive selection? Give an example.

Answer 17

Occurs when conditions favor individuals at both extremes of a phenotypic range over individuals with intermediate phenotypes
Ex: pop. Of seedcracker finches members display two different sized beaks. Small beaked eat soft seed, large beaked eat heard seeds. Birds with intermediated sized bill are inefficient at cracking both types of seeds and thus have lower relative fitness

Question 18

What is the overall mechanism of Selection?

Answer 18

Selection favors individuals who heritable phenotypic traits provide higher reproductive success than do the traits of other individuals