Chapter 20

Question 1

Prokaryote vs Eukaryote DNA

Answer 1

Pro-1 circular chromosomes, no pairs
Euk- linear multiple chromosomes in pairs

Question 2

Autosomal Chromosomes

Answer 2

Non sex
XX Female
XY male

Question 3

Locus (Loci)

Answer 3

Location of Gene on chromosomes

Question 4

Alleles

Answer 4

Alternative form of gene

Question 5

Evolution

Answer 5

Change in allele frequency in a species over time

Question 6

Phenotype=

Answer 6

Genotype + Environment
Physical appearance determined by genotype and environment

Question 7

Genetic Variation

Answer 7

Differences in alleles of genes found within individuals in a pop.

Question 8

Jean-Baptiste Lamarck

Answer 8

Epigenitics- Not changing DNA, turning on/off certain areas of genome

Question 9

Natural Selection

Answer 9

1 Individuals in a pop. vary in traits
2 Traits can be heritable
3 Species with certain traits can survive and reproduce at higher rates than those without those traits

Question 10

Population Genetics

Answer 10

Study of properties of genes in a pop. (Group of individuals of the same spp. in a given area)
Evolution results in a change in the genetic composition of a pop.
Genetic variation is the raw material for selection
In nature, genetic variation is the rule and is required for evolution to occur

Question 11

Hardy Weinberg Equilibrium 5 assuptions
Allele equation
Genotype equation

Answer 11

No mutation
No migration
Random mating
No selection
Large population
Allele equation p (freq of dom allele) q (freq of recessive allele) p+q+1
p²+2pq+q²=1 (P² - freq of homoz dom) 2pq - Freq of heteroz (q² - freq of homoz rec)

Question 12

Five agents of Evolutionary Change

Answer 12

Mutation
Gene flow
Nonrandom mating
Genetic Drift
Selection

Question 13

Mutation

Answer 13

Rates generally low, other processes usually more important in changing allele freq. Ultimate source of genetic variation and makes evolution possible. Usually recessive

Question 14

Gene Flow/Migration

Answer 14

Movement of allele from one population to another. Animal physically moves into a new pop. Drifting gametes or immature stages of plants or animals into area (Ocean current, wind blown seeds). Tends to decrease genetic variability between pops and reduces uniqueness

Question 15

Nonrandom mating. Assortative vs Disassortative

Answer 15

Assortative mating-Phenotypically similar individuals mate. Increases proportion of homozygous individuals, inbreeding concerns (Can increase genetic disease).
Disassortative mating - phenotypically different individuals mate, produces excess of heterozygotes (White throated sparrow stripes and aggressiveness).

Question 16

Genetic Drift

Answer 16

In small populations, allele freq may change by chance alone. Magnitude of genetic drift is inversely related to pop size. Can lead to loss of alleles in isolated pops and uncommon alleles are more vulnerable. Founder effect and bottleneck effect.

Question 17

Founder Effect

Answer 17

One or a few individuals disperse and become the founders of a new, isolated pop. Some alleles are lost, other change in freq. Organisms on islands, self-pollinating plants, Amish, Finns

Question 18

Bottleneck Effect

Answer 18

Drastic reduction in population size due to drought, disease, other natural forces. Survivors may constitute a random genetic sample of original pop. Results in loss genetic variability. Human hunting. Northern Elephant Seal, Bison

Question 19

Selection (Natural vs Artificial)

Answer 19

Some individuals leave behind more progeny (young) than others, and the rate at which they do so is affected by phenotype and behavior.
Artificial selection - Breeders select desired characteristics
Natural selection - Environmental conditions determine which individuals produce the most offspring

Question 20

Conditions to allow for Natural Selection

Answer 20

1 Variation must exist among individuals in a pop.
2 Variation among individuals must result in differences in the number of offspring surviving in the next generation
3 Variation must have a genetic basis (Not learned behavior or teaching)

Question 21

Natural Selection vs Evolution

Answer 21

Natural Selection - Only one of several processes that can result in evolution
Evolution is the historical record, or outcome, of change through time

Question 22

Insecticides

Answer 22

Led to rapid evolution of resistance in more than 500 pest spp.
Housefly pen gene decreases insecticide uptake. kdr and dld-r genes decrease target sites
Evolution resistance to antibiotics in many disease-causing pathogens

Question 23

Fitness

Answer 23

Reproductive success and reflects how well an organism is adapted to its environment.
Individuals with one phenotype leave more surviving offspring in the next generation than individuals with an alternate phenotype
The relative concept is the most fit phenotype is simply the one that produces, on average, the greatest number of offspring
Selection favors phenotypes with the greatest fitness, phenotype increases in frequency

Question 24

Components of fitness

Answer 24

Survival
Sexual selection - some more successful at attracting mates
Number of offspring per mating
Traits favored for one component may be a disadvantage for other

Question 25

Water Striders

Answer 25

Large female water striders lay more eggs per day than small but survive for shorter periods of time. Intermediate sized females produce the most offspring over the course of their lives and thus have the highest fitness

Question 26

Male vs female sexual selection

Answer 26

Females evaluate a male’s quality and then decide whether to mate
Most males only mate, don’t carry eggs, try to mate with as many females as possible

Question 27

Parental Investment

Answer 27

The energy and time each sex invests in producing and rearing offspring
Females have a higher parental investment (typically)
Male Mormon crickets exceed normal by transferring a protein-containing packet to females during mating.

Question 28

Sexual Selection-Intra vs Inter, secondary, dimorphism, sperm competition

Answer 28

Intrasexual selection - competitive interactions between members of one sex. Some males won’t mate, others a lot
Intersexual selection - Mate choice
Secondary sexual characteristics - antlers and horns used to combat other males, long tail feathers and bright plumage used to persuade opposite sex.
Sexual dimorphism - Differences between sexes (male larger than female, color)
Sperm competition - selects for features that increase probability that a male’s sperm will fertilize the egg

Question 29

Intersexual selection Direct vs Indirect

Answer 29

Direct - Female benefit by choosing the male that can provide the best care. Males can provide territory for food and refuge.
Indirect - Higher-quality offspring. Choose the male that is healthiest or oldest. HANDICAP hypothesis - only genetically superior mates survive with a handicap such as a long tail that is a hinderance in flying

Question 30

Sensory Exploitation

Answer 30

Evolution in males of a signal that exploits preexisting biases. Females respond to certain stimuli. Tungara frog, finches with feathers glued to head

Question 31

Maintenance of variation Negative vs Positive frequency-dependent selection

Answer 31

Fitness of a phenotype depends on its frequency within the pop.
Negative freq- Rare phenotypes favored by selection, rare forms may not be in “search image” of predators, preyed upon less frequently. Water boatman - fish eat the most common color by more than chance alone
Positive freq- Favors common form, tends to eliminate variation, oddballs stand out and are picked off. ex. School of fish

Question 32

Oscillating selection

Answer 32

Selection favors one phenotype at one time and another phenotype at another time. Effect will be to maintain genetic variation in the pop. over time. Medium ground finch of Galapagos, birds with big bills favored during drought, small bills favored during wet conditions

Question 33

Heterozygote advantage

Answer 33

Heterozygotes are favored over homozygotes. Works to maintain both alleles in pop. Sickle cell anemia

Question 34

Selection acting on traits affected by multiple genes

Answer 34

Many traits affected by more than one gene. Selection operates on all the genes for the trait. Changes the pop. depending on which genotypes are favored. Types - Disruptive, Directional, Stabilizing: and could oscillate

Question 35

Disruptive selection

Answer 35

Acts to eliminate intermediate types. Two peaks form for ex. “large and small” not intermediate
Different beak size of African black-bellied seedcracker finch. Large beaks for big seeds, small beak for small seed. Intermediate sized beak is too clumsy for small seed not big enough for large seed

Question 36

Directional Selection

Answer 36

Acts to eliminate one extreme. Ex. Fast over slow, or small over big. Often occurs in nature when the environment changes. In Drosophila, eliminated flies that moved toward the light, fewer in pop. over generations. New generations avoid light

Question 37

Stabilizing selection

Answer 37

Acts to eliminate both extremes, makes intermediate more common by eliminating extremes. Humans, infants with intermediate weight at birth have highest survival rate.

Question 38

Natural Selection in guppies

Answer 38

Above waterfall killifish rarely eat guppies, become larger more flashy
Bellow waterfall pike cichlid eat guppies, stay small, reproduce earlier, stay dull

Question 39

Gene flow constructive vs constraining

Answer 39

Constructive - spread beneficial mutation to other populations
Constraining - Can impede adaptation by continual flow of inferior alleles from other populations

Question 40

Examples

Answer 40

Eyes on insect, not genetic environment, not evolution
Thoroughbred horses speed