Chapter 25: Population and Evolutionary Genetics

Question 1

Population

Answer 1

group of individuals with a common set of genes that lives in the same geographic area and actively or potentially interbreeds

Question 2

Gene Pool

Answer 2

all of the alleles present in a population

Question 3

What do most populations contain a high degree of?

Answer 3

heterozygosity

Question 4

Differential reproduction in a population leads to…

Answer 4

-changes in the allele and genotype frequencies in subsquent generations
-microevolution

Question 5

Microevolution

Answer 5

changes in allele frequencies that do not result in reproductive isolation

Question 6

What does the Hardy-Weinberg equation describe?

Answer 6

allele frequencies and genotype frequencies in populations

Question 7

What is the simple mathmateical model that shows the relationship between proportions of alleles in the gene pool and the frequency of different genotypes?

Answer 7

Hardy-Weinberg

Question 8

What are some assumptions made by Hardy-Weinberg?

Answer 8

-there is equal rate of survival and reproduction (no selection occurs)
-no new alleles arise or are created by mutation
-there is no migration into or out of the population
-the population is infintely large
-random mating occurs

Question 9

what are predictions made by Hardy-Weinberg?

Answer 9

the frequency of alleles in the gene pool does not change over time

Question 10

What are some consequences of Hardy-Weinberg?

Answer 10

-dominant traits do not necessarily increase from one generation to the next
-genetic variability can be maintained
-By knowing one genotype, frequencies of others can be calculated

Question 11

What allows the frequency of heterozygotes to be measured?

Answer 11

Hardy-Weinberg

Question 12

What may cause allele frequency to change from one generation to the next?

Answer 12

if individuals are subject to natural selection and do not have equal rates of survival and reproductive success

Question 13

What is the principal force that shifts allele frequencies within large populations?

Answer 13

natural selection

Question 14

What fashion do organisims tend to reproduce in in the Wallace-Darwin Concept of natural selection?

Answer 14

exponential fashion

Question 15

Individuals in a species exhibit ____ in phenotype

Answer 15

variations

Question 16

Are variations heritable?

Answer 16

many of them are

Question 17

What is a trade off of exponential reproduction?

Answer 17

more offspring are produced than can survive. Struggle for survival

Question 18

What do population and species change due to?

Answer 18

natural selection

Question 19

Fitness

Answer 19

an individual’s genetic contribution to the next generation

Question 20

What allows fitness to be examined for each genotype?

Answer 20

Hardy-Weinberg

Question 21

What time frame does weak selection cause substantial changes in allele frequencies?

Answer 21

occurs over thousands of generations

Question 22

What is the fitness of a homozygous recessive individual that dies before producing offspring

Answer 22

w=o

Question 23

What causes rapid changes in allele frequencies?

Answer 23

large differences in genotypes

Question 24

Mutation

Answer 24

only process that creates new alleles in a gene pool

Question 25

Mutation rates

Answer 25

number of new mutant alleles per given number of gametes

Question 26

What does mutation rates look at?

Answer 26

the extent to which mutation can cause allele frequencies to change from one generation to the next can be estimated

Question 27

Migration

Answer 27

occurs when individuals move between populations

Question 28

What is caused by migration?

Answer 28

allele frequencies in these new populations may differ over time

Question 29

Genetic Drift

Answer 29

occurs when the number of reproducing individuals in a population is too small to ensure that all the alleles in the gene pool will be passed on to the next generation in their existing frequencies

Question 30

What results from genetic drift?

Answer 30

may result in one allele becoming fixed and one allele becoming fixed and one allele disapperaring in a population, simply by chance

Question 31

Population bottlenecks occur..

Answer 31

when a large population undergoes a drastic but temporary reduction in numbers

Question 32

What is greatly reduced in a population bottleneck?

Answer 32

genetic diversity

Question 33

Positive assortment mating

Answer 33

similar genotypes are more likely to mate than dissimilar ones

Question 34

Negative assortive mating

Answer 34

in which dissimilar genotypes are more likely to mate than similar ones

Question 35

Inbreeding

Answer 35

mating individuals are related

Question 36

What does inbreeding increase in a population?

Answer 36

number of homozygotes (for a given allele)

Question 37

What will a completely inbred population theoretically consist of?

Answer 37

all homozygotes

Question 38

Species

Answer 38

group of actually or potentially interbreeding organisims that is reproductively isolated in nature from all other such groups

Question 39

Speciation

Answer 39

transforms the gene pool of the parental species or divides a gene pool into two or more seperate and distinct gene pools

Question 40

When can speciation occur?

Answer 40

can occur gradually or within a few generations

Question 41

Macroevolution

Answer 41

genetic changes that result in reproductive isolation between or among populations and lead to the formation of new species

Question 42

what is macroevolution?

Answer 42

microevolution+time

Question 43

Microevolution

Answer 43

alleles change over measurable periods of time

Question 44

Are new species made in microevolution?

Answer 44

no new species

Question 45

What can be used to reconstruct evolutionary histories?

Answer 45

genetic differences among present day species