Chapter 15: Evolution on a small scale

Question 1

Natural Selection

Answer 1

the process that results in the adaptation of a population to the biotic (living) and abiotic (nonliving) components of the environment

Question 2

Types of natural selection

Answer 2

Stabilizing, Directional, Disruptive

Question 3

Natural selection involves

Answer 3

Variation, Inheritance, Increased Fitness

Question 4

Stabilizing selection

Answer 4

occurs when an intermediate phenotype is favored, extreme phenotypes are selected against, and near average is favored. Ex. the number of bird eggs in a clutch

Question 5

Directional selection

Answer 5

occurs when an extreme phenotype is favored and the frequency distribution curve shifts in that direction. can occur when a population is adapting to a changing environment. Ex. Peppered moths, bird game

Question 6

Disruptive selection

Answer 6

two or more extreme phenotypes are favored of any intermediate phenotype. the occurrence of different forms in a population of the same species. Ex. banned and nonbanded snails

Question 7

Sexual selection

Answer 7

refers to adaptive changes in males and females that lead to an increased ability to secure a mate

Question 8

Adaptations are not perfect

Answer 8

natural selection doesn’t always produce perfectly adapted organisms, evolution is constrained by the available variations, and imperfections are common because of necessary compromises Ex. Walking on two feet is slower than walking on 4. Also bad for the spine but good for having hands

Question 9

Maintenance of Variations

Answer 9

populations with limited variation may not be able to adapt to new conditions if the environment changes and thus may become extinct

Question 10

Forces promoting Variation

Answer 10

Mutations, recombinations, independent assortment, and fertilization create new combinations
Gene flow
Natural selection favors certain phenotypes but others remain. Ex. Diploidy and heterozygote

Question 11

Gene flow

Answer 11

might be occurring between two different populations.

Question 12

Heterozygote advantage

Answer 12

a potential protector of recessive that might otherwise be weeded out of the gene pool. Bb +Bb = BB, Bb, Bb, Bb, bb.

Question 13

Microevolution

Answer 13

small, measurable evolutionary changes in a population from generation to generation; change in allele frequencies within a population over time. Individuals do not evolve

Question 14

Gene pool

Answer 14

various alleles at all gene loci in all individuals make up the gene pool of a population.

Question 15

Population genetics

Answer 15

Study of gene frequencies and their changes within a population

Question 16

Hardy-Weinberg equilibrium

Answer 16

allows us to determine if evolution is occurring in a population. Ex. if it matches the numbers no evolution happened. if no match, then evolution is occurring. depending on which allele changes are made can tell is which selection

Question 17

Mathematical relationships of Hardy Weinberg

Answer 17

No mutations, no gene flow, random mating, no genetic draft, selection

Question 18

No mutations

Answer 18

allelic changes do not occur, or changes in one direction are balanced by changes in the opposite direction

Question 19

No gene flow

Answer 19

migration of alleles into or out of the population does not occur

Question 20

Random mating

Answer 20

individuals pair by chance, not according to their genotypes of phenotypes

Question 21

No genetic drift

Answer 21

population is very large, and changes in allele frequencies due to chance alone are insignificant

Question 22

Selection

Answer 22

natural selection is not occur or does not favor any allele or combination of alleles over another

Question 23

Mutations

Answer 23

permanent genetic changes are the raw material for evolutionary change

Question 24

Gene flow

Answer 24

the movement of alleles among populations by migration of breeding individuals

Question 25

Nonrandom mating

Answer 25

mating that does not occur purely random basis. Ex. Inbreeding or sexual selection

Question 26

Genetic drift

Answer 26

refers to changes in the allele frequencies of a gene pool due to chance

Question 27

bottleneck effect

Answer 27

Evolutionary even in which a significant percentage of a population is prevented from reproducing, therefore reducing variation and increasing the genetic drift

Question 28

Founder effect

Answer 28

mechanism of genetic drift in which rare alleles or combinations of alleles occur at a higher frequency in a population isolated from the general population