Campbell Biology: Cambell Flashcards


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Campbell Biology
Chapters 22-26
updated 9 years ago by bryanbalducki
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College: Third year
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1

Heritability

ability of a trait to be passed on to offspring

2

Evolution

Decent with modification

3

Adaptation

inherited characteristics of organisms that enhance their fitness in specific envrionments

4

Fitness

quantifiable measure of survival and reproductive success

5

Natural Selection

process in which individuals that have certain inherited traits tend to have a higher fitness because of those adaptations

6

For natural selection to work: (3 aspects must occur)

Variation: 1. must be present in the population
2. must affect fitness
3. must be inherited

7

Artificial selection

the process in which humans modify organisms by selecting and breeding organisms with certain traits

8

Homologous structures

structures in different species that have a general theme because of common ancestry, but structures may vary in form and function

9

Vestigial structures

remnants of structures that serve an important function in the ancestor, but not in the present organism

10

Biogeography

the geographic distribution of species

11

Convergent evolution

the independent evolution of similar features in different lineages due to similar environmental pressures

12

microevolution

The change in allele frequencies in a population over time

13

populations

all the individuals of one species in a particular area

14

Genes

a discrete unit of hereditary info. consisting of a specific nucleotide sequence in DNA

15

Genotype

the genetic makeup, or set of alleles, of an organism

16

Allele

any alternative versions of a gene that may produce distinguishable phenotypic effects

17

Phenotype

observable traits of an organism that are determined by genotype

18

Dominant phenotype

homozygous dominant or heterozygous genotype

19

Recessive phenotype

homozygous recessive genotype

20

genetic variation

differences among individuals in the composition of their genes or other DNA segments

21

Phenotypic plasticity

variations in appearance due to environmental influences

22

2 ways to measure genetic variation:

1. nucleotide variability- at the molecular level of DNA
2. gene variability- at the whole gene level, which is quantified by average heterozygosity

23

Geographic variation

differences in the genetic composition of separate populations

24

cline

a graded change in character along a geographic axis

25

Sources of genetic variation

1. Formation of new alleles through mutation
2. Altering gene number or position through chromosomal changes that delete, disrupt, or rearrange loci
3. Rapid reproduction can increase mutation rates
4. Sexual reproduction due to: crossing over, independent assortment of alleles, fertilization

26

Hardy-Weinberg principle: original proportions of genotypes within a population will remain the same if:

1. no mutations
2. no gene flow
3. random mating occurs
4. population size is large
5. no selection occurs

27

Hardy Weinberg allele frequency equation

p+q=1

28

Hardy Weinberg genotype frequency equation

p(squared)+ 2pq + q(squared)=1

29

Genetic drift

chance events that can cause unpredictable fluctuations in allele frequencies from one generation to the next

30

Genetic drift example: Founder effect

When a few individuals become isolated from a larger population

31

Genetic drift example: Bottleneck effect

a reduction of population size due to a sudden change in environment

32

Gene flow

movement of alleles into or out of a population

immigration- move into
emigration- move out of

33

Natural Selection

process in which individuals that have certain inherited traits tend to have higher fitness because of those adaptations

34

Relative fitness

contribution an individual makes to the gene pool of the next generation relative to the contributions of other individuals

35

Directional-

natural selecting can alter frequency distribution

one end of distribution is favored

36

Disruptive-

natural selecting can alter frequency distribution

both ends of the distribution are favored

37

Stabilizing-

natural selecting can alter frequency distribution

intermediates of the distribution are favored

38

Sexual selection

a form of selection in which individuals with certain phenotypes are most likely than others to obtain mates

39

Intra-sexual selection

individuals of the same sex compete for access to mates

40

Inter-sexual selection

individuals of one sex choose their mates of the opposite sex

41

Balancing selection

occurs when natural selection maintains variation in the population
2 ways: Heterozygote advantage
Frequency dependent selection

42

Heterozygotes advantage

heterozygotes have a greater fitness than both homozygotes

43

Frequency-dependent selection

the fitness of the phenotype depends on how common it is in the population

44

Why natural selection cannot fashion perfect organisms????

1. selection can act only on existing variations
2. evolution is limited by historical constraints
3. adaptations are often compromises
4. chance, natural selection, and the environment interact

45

Speciation

the process by which one species splits into 2 or more species

46

Biological species concept

defines species as a group of populations whose members have the potential to interbreed in nature and produce viable, fertile offspring, but do not produce viable, fertile offspring with member of other such groups.

47

Reproductive isolation

the existence of biological factors(barriers) that impede members of 2 species from interbreeding and producing viable, fertile offspring

48

pre-zygotic barrier

block fertilization from occuring

49

Post-zygotic barriers

reproductive isolation occurs after the hybrid zygote is formed

50

Habitat isolation

species occupy different habitats with in the same area and therefore rarley encounter each other

51

Temporal isolation

species that breed during different times of the day, season, or years

52

Behavioral isolation

courtship rituals that attracts mates and enables mate recognition

53

Mechanical isolation

Mating is attempted, but morphological differences prevent a successful completion

54

Gametic isolation

mating is attempted, but the sperm of one species is unable to fertilize the egg of another species

55

Reduced hybrid viability

Zygote forms but either the embryo does not develop or the offspring doesn't survive in its environment

56

Reduced hybrid fertility

the hybrid is healthy, but is infertile and cannot produce offspring

57

Hybrid breakdown

when a viable, fertile hybrid reproduces, but their offspring are feeble or sterile

58

Morphological species concept-

characterizes species by body shape and structure features

59

Ecological Species concept

defines species based on ecological niche

60

Phylogenetic species concept

defines species as the smallest group of individuals that share a common ancestor

61

Allopatric speciation

occurs because gene flow is interrupted when a population becomes geographically isolated

62

Sympatric speciation

speciation occurs without geographic separation

63

Polyploidy

an accident in cell division that results in extra set of chromosomes

64

Habitat differentiation

genetic factors enable a subpopulation to exploit a habitat or resource not used by the present population

65

Sexual selection

a subset of the population starts choosing the opposite sex based on specific characteristics

66

Hybrid zones

a region in which members of different species meet and mate, producing some offspring of mixed ancestry

67

Reinforcement

process of natural selection strengthening the pre-zygotic barriers reducing the chances of hybrid formation

68

Fusion

weak reproductive barriers increase gene flow between the 2 species causing the 2 hybrid species to fuse into single species

69

Stability

Hybrids continue to be produced because the hybrids survive and/or reproduce better than the parent species

70

Punctuated equilibrium

periods of stasis followed by sudden change

71

Gradualism

change occurs gradually over long periods of time

72

Macroevolution

broad pattern of evolution above the species level
-revealed through fossil record

73

4 main stages the could have produced the first sell:

1. the abiotic synthesis of small organic molecules, such as AA and nitrogenous bases
2. the joining of these small molecules into macromolecules
3. the packaging of these molecules into protocell droplets with membranes that maintained internal chemistry different from the surroundings
4. The origin of the self-replicating molecules that eventually made inheritance possible

74

Radiometric dating

a technique of dating rocks and fossils based on the fixed rate of radioactive isotope decay

75

Half life

Amount of time required for 50% of the parent isotope to decay

76

Eukaryotes, organisms with membrane-bound organelles, evolved through:

-infolding of plasma membrane--created ER, nuclear membrane
-endosymbiotic theory-cell engulfing a prokaryote---created mitochondria, chloroplasts, plastids

77

Why is Multicellularity important?
hypothesis?

Led to the great innovation of specialization
- Colonial unicellular organisms let to multicellular organisms

78

cambrian explosion

burst of evolutionary change that occured in a short geological period , which includes the appearance of many present day animal phyla

79

Continental drift

process in which the earth's mantle causes the continental plates to move
-promotes allopatric speciation on a grand scale

80

Adaptive radiation

periods of evolutionary change in which groups of organisms form many new species whose adaptations allow them to fill different ecological roles in their communities

81

Horse fossils show 3 trends:

1. larger size
2.more complex molar teeth
3. fewer toes

82

Permian period

most extensive loss. 96% of plants and animal species perished

83

Cretaceous period

most famous and well studies. Caused by meteorite causing mass forest fire and smoke blocked sun, dinosaurs died off while placental mammals flourished

84

Taxonomy

disciplin in which organisms are named and classified

85

Taxa

taxonomic unit at any level

86

Binomial nomenclature

the scientific name of an organism that consists of a genus and species

87

Systematics

a discipline focused on classifying organisms and determining their evolutionary relationships

88

Phylogeny

the evolutionary history of a species or group of species

89

phylogenetic tree

branching diagram that represent the evolutionary history of a group of organisms

90

nodes

represent common ancestor

91

branch point

where lineages diverge

92

polytomy

a branch point where more than 2 taxa emerge

93

sister taxa

groups that share an immediate common ancestor

94

Basal taxon

lineage that diverges early in the history of the group

95

Homology

genotypic and phenotypic similarities due to sharing ancestry

96

Analogy

Phenotypic similarities, but no shared ancestry

97

Convergent evolution

process of similar adaptations evolving in organisms from different evolutionary lineages due to similar environmental pressures

98

Outgroup

a taxa that is closely related to the group of organisms that you are studying, but are not part of your study group

99

synaphories

shared derived characters that represent departure from the ancestor

100

Sympleslomorphies

shared ancestral characters that evolved prior to the most recent common ancestor

101

Monophyletic

a group that consists of the ancestral species and all of its descendants

102

Paraphyletic

a group that consists of the ancestral species and some, but not all of its descendants

103

Polyphyletic

a group that doesn't include the closest common ancestor

104

3 domains?

Archaea
Bacteria
Eukarya

105

kingdoms of Eukarya:

Plantae
Fungi
Animalia
Protista