Ch. 10: Evolution

Question 1

Evolution

Answer 1

the process by which frequency of heritable traits in a pop. changes from one generation to the next

Question 2

Theory or Jean-Baptiste Lamarck

Answer 2

1. Use and disuse: body parts of organisms develop w/ increased usage while unused parts weaken
2. Inheritance of acquired characteristics: body features acquired in lifetime can be passed to offspring… false. only changes in DNA can be passed to offspring

Question 3

Darwin’s theory of evolution

Answer 3

The Origin of Species

natural selection and “survival of the fittest”

Question 4

Paleontology (evolution)

Answer 4

provides fossils that reveal the prehistoric existence of extinct species so changes can be studied

• often found among sediment layers, where deep = old
• age of fossil can be determined by C-14 dating

Question 5

Biogeography (evolution)

Answer 5

geography used to describe distribution of species
unrelated species in different regions of the world look alike when in similar environments so provides evidence for natural selection
Ex. sugar glider of Australia and flying squirrel of North America

Question 6

Embryology (evolution)

Answer 6

similar stages in development (ontogeny) among related species –> help est. evolutionary relationships (phylogeny)
Ex. gills and tails found in fish, chicken, pig, and human embryos

Question 7

Homologous structures

Answer 7

body parts that resemble one another in different species bc they have evolved from a common ancestor
may look different but be similar in pattern
Ex. forelimbs of cats, bats, whales, and humans all have similar bone structure

Question 8

Vestigial structures

Answer 8

homologous structures that have lost their function

Ex. limbs in snakes, wings of flightless birds

Question 9

Analogous structures

Answer 9

body parts that resemble one another in different species that evolved independently as adaptations to their environment
Ex. fins in fish or wings in birds

Question 10

Molecular biology (evolution)

Answer 10

examines nucleotide and DNA similarities between related species… more related DNA = more related species
also, all living things share the same genetic code

Question 11

Natural selection

Answer 11

differences in survival and reproduction among individuals in a pop. as a result of their interaction with the environment
some alleles suit organisms more favorably towards their environment

Question 12

Adaptations –> fitness

Answer 12

superior traits increase organisms likelihood of survival and pass on these good traits to offspring, while those w bad traits die

Question 13

Darwin’s theory of natural selection (8)

Answer 13

1. Populations possess an enormous reproductive potential
2. Population sizes remain stable
3. Resources are limited: as pop. grows larger, food/ water/ light does not increase
4. Individuals compete for survival: bc of #3
5. There is variation among individuals in a population
6. Much variation is heritable: acquired traits are not passed on
7. Only them most fit individuals survive
8. Evolution occurs as favorable traits accumulate in the pop.: changes in proportion of gene pool

Question 14

Stabilizing selection graph

Answer 14

peak in middle, bell curve like shape

Question 15

Directional selection graph

Answer 15

peak on one side, either left or right

Question 16

Disruptive selection graph

Answer 16

2 peaks on each side left and right, dip in middle

Question 17

Sexual selection graph

Answer 17

similar to disruptive w/ 2 peaks on each side but one bears more area (male/ female)

Question 18

Stabilizing selection

Answer 18

eliminates those w/ extreme/ unusual traits so those w/ most common trait are best adapted and thus best represented in pop.
maintains existing population frequencies of common traits and selects against other trait variations

Question 19

Directional selection

Answer 19

favors traits at one extreme of a range of traits, and the other extreme is selected against
over many generations favored traits become more and more extreme and allele frequencies in pop. change
Ex. finch’s beaks, insecticide resistance, peppered moth, season creep

Question 20

Peppered moth (industrial melanism)

Answer 20

ex. of directional selection
light moth was good before industrial revolution bc blended in, and dark moth not really seen bc easily spotted to be eaten. then soot made dark moth more easily camouflaged so that was the trait selected for

Question 21

Disruptive selection

Answer 21

environment favors extreme or unusual traits while selecting against common ones
Ex. weeds are either really tall in wild of really short to avoid mowing

Question 22

Sexual selection, Male competition, Female choice, Sexual dimorphism

Answer 22

differential mating of males and females in a pop.
females look for quality males look for quantity
Male competition: contests of strength with strongest male getting to mate; antlers, horns, muscles
Female choice: traits or behaviors in males that are attractive to females; colorful plumage or elaborate mating
sexual selection often leads to sexual dimorphism which is form of disruptive selection

Question 23

Artificial selection

Answer 23

form of directional selection carried out by humans to get desired traits
Ex. dog breeding, modification of crops

Question 24

Sources of variation in evolution

Answer 24

mutations, sexual reproduction and genetic recombination, diploidy, outbreeding, balanced polymorphism and the heterozygote advantage/ hybrid vigor/ frequency-dependent selection

Question 25

Mutations (variation)

Answer 25

provide raw material for new variation, invent alleles that never existed in gene pool and can then be rearranged even more Ex. antibiotic and pesticide resistance introduced in pop. by random mutation, although these alleles may have already existed in pop. the introduction of antibiotics "selected" for those individuals

Question 26

Sexual reproduction (variation)

Answer 26

creates individuals w/ new combinations of alleles (genetic recombination) 1. Crossing over (prophase I of meiosis) 2. Independent assortment of homologues 3. Random joining of gametes

Question 27

Diploidy (variation)

Answer 27

presence of two copies of each chromosome in a cell so there are two alleles at a single gene locus, so allowed for recessive to be hidden under dominant which is more variation bc more alleles

Question 28

Outbreeding (variation)

Answer 28

mating with unrelated partners increases possibility of mixing diff. alleles and create new allele combinations

Question 29

``` Balanced polymorphism (variation) Heterozygote advantage Hybrid vigor (heterosis) Frequency-dependent selection (minority advantage) ```

Answer 29

maintenance of different phenotypes in pop. many times, one phenotype is more advantageous, so the other alleles decreased are selected against, but polymorphism (2+ phenotypes) is maintained by: - Heterozygote advantage: Ex. sickle cell disease homozygous is healthy/ fatal but heterozygous just weakens the blood oxygen carrying ability, but provides resistance to malaria so lots of ppl in Africa have it. keeps all three combos feasible - Hybrid vigor: superior quality of offspring from crosses between two diff. inbred strains of plants - Frequency-dependent selection (minority advantage): least common phenotypes are selected for. but as they're selected for they become common so are selected against. pop. fluctuates between low and high frequencies of trait

Question 30

Human impact on variation (thus evolutionary potential)

Answer 30

reduce size and thus genetic variation of pop through - Monocultures: only one of many vile varieties of plants are used, wild varieties die, these types of plants have no genetic variation so v susceptible to disease/ environmental change - Overuse of antibiotics: we have made bacteria resistant

Question 31

Natural selection (allele frequency)

Answer 31

increase or decrease in allele frequency due to impact of environment

Question 32

Mutations (allele frequency)

Answer 32

introduce new alleles that may provide selective advantage, though most are deleterious (harmful)

Question 33

Gene flow (allele frequency)

Answer 33

movement of individuals between populations resulting in the removal of alleles from the pop. when they leave (emigration) and introduction of alleles when they enter (immigration)

Question 34

Genetic drift (allele frequency)

Answer 34

random increase or decrease of alleles, happens by chance when pop. is small, effect of genetic drift can be v strong and dramatically influence evolution think stats

Question 35

Founder effect (genetic drift)

Answer 35

allele frequencies in a group of migrating individuals are, by chance, not the same as their pop. of origin loss of genetic variation when smaller pop. is est. from larger one Ex. polydactyly is common in Amish

Question 36

Bottleneck effect (genetic drift)

Answer 36

population undergoes dramatic decrease in size regardless of cause (catastrophe, predation, disease) the small resulting pop. is v vulnerable to genetic drift when bottlenecks caused by forces that strike individuals randomly, gene frequencies may change by chance like geological events

Question 37

Nonrandom mating (allele frequency)

Answer 37

individuals choose mates based on specific traits and only alleles possessed by mating individuals passed down Ex. inbreeding, sexual selection

Question 38

Hardy-Weinberg equilibrium (conditions)

Answer 38

allele frequencies in a pop. remain constant from generation to generation, and there is no evolution 1. All traits are selectively neutral (no natural selection) 2. Mutations do not occur 3. The population must be isolated from other populations (no gene flow) 4. The population is large (no genetic drift) 5. Mating is random will never happen, but used to show how allele frequencies are changing, which conditions are being violated and what mechanisms are driving evolution of pop.

Question 39

Genetic equilibrium formulas and variables

Answer 39

- p, q: frequency of each allele - p^2: frequency of homozygous dominant genotype - q^2: frequency of homozygous recessive genotype - 2pq: frequency of heterozygous genotype - p + q = 1 (all alleles sum to 100%) - p^2 + 2pq + q^2 = 1 (all individuals sum to 100%)

Question 40

Allopatric speciation

Answer 40

pop. is divided by a geographic barrier (mountains, rivers), preventing mating between the two groups once reproductively isolated, gene frequencies in the two pop.s can diverge due to natural selection (environments might be different), mutation, or genetic drift; over time become so different that can no longer mate w/ each other and speciation has occured [geographic barrier --> reproductive isolation --> differential evolution --> reproductive barriers --> new species]

Question 41

Sympatric speciation

Answer 41

formation of new species w/ out geographic barrier | Ex. balanced polymorphism, polyploidy, hybridization

Question 42

Balanced polymorphism (sympatric speciation)

Answer 42

may lead to speciation Ex. population of insects has polymorphism for color, and each color provides camouflage to diff. things. if not camouflaged, is eaten so only insects w/ same color can associate and mate --> same colored insects reproductively isolated from other subpopulations and their gene pools diverge

Question 43

Polyploidy (sympatric speciation)

Answer 43

possession of more than normal 2n set of chromosomes often found in plants where 3n and 4n are ok and common diploid + diploid = tetraploid zygote; this tetraploid will continue to produce diploid games so reproductive isolation (speciation) occurs within one generation

Question 44

Hybridization (sympatric speciation)

Answer 44

two different forms of species (or closely related species normally reproductively isolated) mate and produce progeny along geographic boundary called hybrid zone these individuals adapt to hybrid zone and eventually diverge

Question 45

Adaptive radiation

Answer 45

relatively rapid evolution of many species from a single ancestor occurs when ancestral species introduced to area where diverse geographic/ ecological conditions available available and variants adapt to each and diverge Ex. marsupials of Australia, 14 Galapagos finches, occurred after each of the 5 big mass extinctions

Question 46

Pre-zygotic isolating mechanisms | Habitat isolation, Temporal isolation, Behavioral isolation, Mechanical isolation, Gametic isolation

Answer 46

mechanisms that prevent fertilization to maintain reproductive isolation w/out geographic barrier between species 1. Habitat isolation: species don't encounter each other 2. Temporal isolation: different mating seasons 3. Behavioral isolation: don't recognize another species for mating bc of improper mating rituals/ signals 4. Mechanical isolation: can't do the do 5. Gametic isolation: the gametes of one sex do not survive in the environment of gametes of the other sex

Question 47

Post-zygotic isolating mechanisms | Hybrid inviability, Hybrid sterility, Hybrid breakdown

Answer 47

mechanisms that prevent the formation of fertile progeny to maintain reproductive isolation w/out geographic barrie between species 6. Hybrid inviability: zygote fails to develop properly and dies before being able to reproduce 7. Hybrid sterility: donkey + horse = mule can't have babies 8: Hybrid breakdown: hybrids produce offspring w/ reduces viability/ fertility

Question 48

Patterns of evolution (4)

Answer 48

1. Divergent evolution 2. Convergent evolution 3. Parallel evolution 4. Coevolution

Question 49

Divergent evolution

Answer 49

2+ species that originate from a common ancestor and become increasingly different over time may happen as result of allopatric or sympatric speciation or by adaptive radiation

Question 50

Convergent evolution

Answer 50

describes two unrelated species that share similar (analogous) traits that resulted not bc of common ancestor, but bc each species had independently adapted to similar ecological conditions/ lifestyles Ex. sharks, penguins and dolphins have fins

Question 51

Parallel evolution

Answer 51

two related species/ two related lineages that have made similar evolutionary changes after their diverges from a common ancestor Ex. marsupial and placental mammals have independently evolved similar adaptations when ancestors encountered compatible environments

Question 52

Coevolution

Answer 52

one species evolves in response to new adaptations in another species Ex. prey starts to run faster so predator also runs faster (allele wise bc selection) occurs between predator and prey, plants and plant-eating insects, pathogens and animal immune systems

Question 53

Microevolution

Answer 53

details of how populations of organisms change from generation to generation and how new species originate

Question 54

Macroevolution, Phylogeny

Answer 54

general pattens of change in groups of related species that have occurred over broad periods of geologic time patterns determine phylogeny: evolutionary relationships among species/ groups of species fossil evidence has led to two contrasting theories: phyletic gradualism, punctuated equilibrium

Question 55

Phyletic gradualism (macroevolution)

Answer 55

argues that evolution occurs by the gradual accumulation of small changes individual speciation events/ major changes in lineages occur over long periods of geologic time w/ fossil evidence providing only snapshots of evolutionary process and showing only major changes, intermediate stages not represented testifying incompleteness of fossil record

Question 56

Punctuated equilibrium (macroevolution)

Answer 56

argues that evolutionary history consists of geologically long periods of stasis w/ no evolution, interrupted by geologically short periods of rapid evolution ranging over tens of thousands of years fossil record consists of fossils mostly from stasis period w/ few from short evolutionary bursts; absence of intermediate fossils is confirmation of this rapid evolution

Question 57

Chemical evolution

Answer 57

study of how life began and formation of first living things

Question 58

How old is the Earth?

Answer 58

4.6 billion years, inhospitable for life for billions of years

Question 59

Primordial atmosphere

Answer 59

primarily of CO2 and N2, but little or no O2

Question 60

Stanley Miller experiment

Answer 60

simulated primordial conditions by applying electric sparks to simple gases (no oxygen) connected to a flask of heated water, after a week the water contained various organic molecules including amino acids

Question 61

Protobiont

Answer 61

precursors of cells, able to carry out chemical reactions within a membrane like border

Question 62

Endosymbiotic theory

Answer 62

describes how eukaryotic cells originated from a mutually beneficial association among various kinds of prokaryotes specifically, mitochondria, chloroplasts, and other organelles est. residence inside another prokaryote to make eukaryote

Question 63

Endosymbiotic theory evidence

Answer 63

Mitochondria and chloroplasts have their own DNA and ribosomes which is similar to that of bacteria Mitochondria and chloroplasts reproduce independently of their eukaryotic host cell by process similar to binary fission of bacteria, and have two membranes

Question 64

Origin of life steps (9)

Answer 64

1. Earth and its atmosphere formed 4.6 bya 2. Primordial seas formed as Earth cooled 3. Organic molecules synthesized: "soup" w/ UV energy, amino acids formed 4. Polymers and self-replicating molecules were synthesized: RNA world hypothesis 5. Organic molecules were concentrated and isolated into protobionts: liposomes 6. Primitive heterotrophic prokaryotes formed ~3.9 bya 7. Primitive autotrophic prokaryotes were formed 8. Oxygen and ozone layer formed and abiotic chemical evolution ended 9. Eukaryotes formed (endosymbiotic theory)