Biology Evolution Exam 3

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134 Terms

1

Where are substitutions more common?

at positions that do not change the amino acid

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2

What does neutral mean?

don't convey a selective advantage or disadvantage

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3

What does the molecular clock do?

helps you calculate how long it has been since two species "diverged" from a common ancestor

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4

What is positive directional selection?

rate of non-synonymous substitution exceeds the rate of synonymous substitution

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5

What is neutral selection?

rate of non-synonymous substitution equals the rate of synonymous substitution

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6

What is a form of stabilizing or purifying selection?

rate of non-synonymous substitution is less than the rate of synonymous substitutions

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7

Where is genetic drift stronger: smaller or larger populations?

small populations

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8

What does sexual recombination lead to?

leads to genetic variability in offspring

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9

What are some of the disadvantages of sexual reproduction?

only 50% of the female genes are passed on; recombination separates adaptive gene combinations

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10

What are the advantages of sexual reproduction?

recombinations can separate deleterious combinations; homologous chromosomes are used to repair damaged DNA; recombination introduces genetic variation

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11

What is the main advantage of asexual reproduction?

increased fitness

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12

What are some of the disadvantages of asexual reproduction?

no way to eliminate deleterious mutations

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13

What is lateral or horizontal gene transfer?

process by genes, organelles, or fragments of entire genomes move from one lineage to another

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14

What is gene duplication?

entirely new copy of a gene appears in a genome over evolutionary time

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15

What is a gene family?

group of homologous genes that have related functions

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16

What is speciation?

process in which biological lineages diverge due to reproductive isolation, resulting in new species

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17

What are sister species?

each one is the other's closest relative

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18

What is the morphological species concept?

defines a species based on observable morphological characteristics such as body shape, size, color, and other structural features

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19

What are some of the problems of the morphological species concept?

members of the same species may look alike; members of the different species may look similar

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20

What is the biological species concept?

two organisms are of the same species if they can mate with one another

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21

What is the main idea of the biological species concept?

groups of actually or potentially interbreeding natural populations that are reproductively isolated

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22

What is reproductive isolation?

situation in which two groups of organisms are unable to exchange genes

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23

What are the disadvantages of the biological species concept?

does not apply to asexual organisms; cannot be applied to extinct species; ring species are too distantly related to interbreed

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24

What is the lineage species concept?

two groups that share a branch on the tree of life

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25

What does speciation require>

requires an interruption in gene flow

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26

What does the Dobzhansky-muller model explain?

explains how a single lineage can split into two reproductively isolated species; overtime, the two species will be unable to mix and will be considered two different species

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27

When does reproductive isolation increase?

when a species diverges genetically

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28

What is allopatric speciation?

population is divided by a physical or geographic barrier, forming two reproductively isolated populations that evolve independently

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29

What is sympatric speciation?

species arise from a population that remains connected

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30

What does disruptive selection do?

favors two extreme phenotypes and results int eh divergence between two species

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31

What is temporal isolation?

flower at different times; breed at different times of the year

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32

What does polyploidy mean?

mistake during cell division results in an individual with cells that have more than one copy of teh genome

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33

autopolyploidy

duplication of a set of chromosomes in a single species

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34

allopolyploidy

chromosomes of two different species are combined

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35

incipient species

species that are in the process of diverging into separate species, but can currently interbreed

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36

What is a prezygotic isolating mechanism?

prevents hybridization; prohibits individuals of different species from attempting to mate

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37

What is mechanical isolation?

some animals are simply not physically compatible with other animals due to anatomical differences

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38

What is temporal isolation?

never have the opportunity to reproduce with the other due to the timing of reproduction

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39

What is behavioral isolation?

pairing of mates does not occur unless the correct mating rituals or signals are performed (certain frogs will only mate with individuals who make a specific kind of mating call)

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40

habitat isolation

some animals are isolated by space such that they never have the opportunity to come into contact with one another

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41

What is gametic isolation?

some animals produce sperm and eggs that simply will not fuse when they come into contact (important in aquatic communities)

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42

What is a postzygotic isolating mechanism?

reproductive barriers that prevent interbreeding after the development of the zygote; reduce the fitness of the hybrid offspring

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43

What are some of the post-zygotic mechanisms?

reduced genetic compatibility; low hybrid zygote viability; low adult hybrid viability; hybrid infertility

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44

Why does natural selection tend to favor pre-zygotic mechanisms?

it is easier to prevent reproduction from occurring in the first place

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45

Where are pre-zygotic reproductive barriers stronger?

populations living in sympatry have stronger reproductive barriers because they prevent hybridization from occurring (hybridization already occurs in allopatric speciation)

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46

What does a phylogeny do?

describes the evolutionary history of the relationships between living things

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47

What is a node?

point where two branches separate

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48

What does the root represent in a phylogenetic tree?

common ancestor that all organisms share

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49

What may or may not mean something on a phylogenetic tree?

branch length

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50

What is special about the order of things on a phylogenetic tree?

nodes can spin around; you can swivel the branches at the top node without changing the relationships

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51

What is a taxon?

group of species with a name

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52

What is a sister species?

species that directly evolve from a common ancestor

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53

monophyletic clades

groups of taxa that include an ancestor and all of its descendants

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54

What are sister clades?

two clades that are each other's closest relatives

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55

what is systematics?

study and classification of biodiversity

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56

What is homology?

any heritable trait shared by more than one species and inherited from a common ancestor

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57

What is a derived trait?

evolved from an earlier condition

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58

What is a synapomorphy?

shared, derived traits that provide evidence of common ancestry

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59

What is special about the relationship of homology and synapomorphy?

all synapomorphies are homologous but not all homologies are snapomorphies

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60

What are homoplasies a result of?

convergent evolution or evolutionary reversal

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61

What are homoplasies?

traits that are shared not due to evolutionary history but rather because fo convergent evolution or evolutionary reversals

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62

What is convergent evolution?

similar traits evolve in different lineages; share homoplasies that are common to the different species but have independent evolutionary origins

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63

What homoplasies commonly lead to?

false or incorrect conclusions

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64

What is evolutionary reversal?

character reverts from a derived state back to an ancestral state

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65

What is the goal of a phylogeny?

parsimony principle; simplest explanation for observed date is the best explanation; eliminates the number of evolutionary changes and homoplasies in the tree

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66

What is the outgroup?

species closely related to the ingroup, but not closely related enough the be inside the group of interest

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67

What is the purpose of the outgroup?

outgroup provides something to compare to and see where/when traits evolved

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68

What is the ingroup?

groups of organisms we are interested in

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69

What are ancestral traits?

traits of the ingroup that are the same in the outgroup

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70

What are derived traits?

traits are different from those in the outgroup

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71

What is morphology used for?

way to classify extinct species

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72

What is a disadvantage of behavior?

it is hard to measure behavior and it is greatly influenced by the environment

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73

What does a molecular clock do?

groups the # of nucleotide differences against the times of a series of evolutionary branch points that are known from the fossil record or known times of divergence

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74

What is the order of classification?

King Philip Came Over For Good Sex

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75

What is a monophyletic grouping?

contains an ancestor and all of its descendants

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76

What is paraphyletic grouping?

contains teh ancestor and some of its descendants

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77

What is polyphyletic grouping?

does not contain its common ancestor

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78

What is stratigraphy?

determine how old a rock is compared to other rocks

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79

What is a sedimentary rock?

top layers are newer and bottom layers are older

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80

What does an actual dating method measure?

determines the actual age of teh rock

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81

What does carbon dating do?

determines how old organic matter is (must be 60000 years old or younger)

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82

How are igneous rocks formed)

rocks are formed when the molten rocks cool

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83

What is radiometric dating?

determines how old something is based on the proportion of radioactive isotopes to normal isotopes found in it

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84

What is a major disadvantage of fossils?

most organisms do not fossilize; many fossils are destroyed over time and are not ever found

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85

What is continental drift?

movement of the Earth's plates, which produces significant change in the physical environment

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86

What is speciation?

formation of new and distinct species in the course of evolution

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87

What often declines as the globe cools and more glaciers form?

sea levels decline

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88

What are stromatolites?

contain living colonies of cyanobacteria

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89

What does decay require?

requires oxygen

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90

What was the cambrian explosion?

huge diversification of multiceulluar life

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91

What happened during the permian period?

continents collide to form pangea

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92

What happened during the cretaceous period?

mass extinction due to a meteorite

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93

Which selection reduces variance without changing the mean value of a trait?

stabilizing selection

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94

What selection changes the mean while not changing the variance?

directional selection

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95

What selection changes the variance but may or may not change the mean?

disruptional selection

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96

What selection creates a bimodal distribution?

disruptional selection

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97

What selection favors the intermediate value?

stabilizing selection

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98

Which selection favors one extreme?

directional selection

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99

Which selection favors both extremes?

disruptional selection

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100

What selection favors the common phenotype?

positive selection

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