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Midterm 1 Flashcards

1
Q

Evolution

A

genetic change in a population

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2
Q

Natural Selection

A

consequence of certain individual organisms in population being born with characteristics that enable them to survive better and reproduce more than offspring of other individuals in population

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3
Q

4 principles of evolution

A

1) all life is linked through a common ancestor
2) Populations of living things change with time
3) Environment influences this change (through natural selection)
4) descent through modification

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4
Q

Charles Darwin

A

at age 16 he travelled to the Galapagos and studied finches (different beaks), armadillo fossils, plants and animals that differed from on the mainland

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5
Q

Traits exhibited by species (Darwin discoveries)

A

1) finches had different shaped beaks based on what their diet was
2) similarities based on fossils found and the living species around that area

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6
Q

Adaptation

A

biological definition: a trait that benefitted an organism in a particular environment

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7
Q

Fitness

A

an organism’s ability to survive or reproduce in a particular environment

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8
Q

3 important elements of fitness

A

1) fitness is measured relative to species’ genotypes and phenotypes
2) fitness depends on environment the individual lives in
3) fitness depends on reproductive success compared to other organisms in the same population

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9
Q

How does natural selection operate?

A

1) Variation in trait (different traits are present in individuals of same species)
2) mode of inheritance (must be on an allele in order for it to be passed on)
3) fitness consequences for trait (individuals with traits suited for reproduction generally leave more offspring)

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10
Q

Artificial Selection

A

process of humans choosing certain varieties of an organism over others

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11
Q

Evidence for evolution

A

1) Homologies
2) The Fossil Record
3) Biogeography

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12
Q

Direct observation

A

we can see evolution occurring in bacteria which have a short lifespan

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13
Q

Homology

A

similarity with ancestors:

Characteristics present in ancestral organism altered over time by natural selection as its descendants face different environmental conditions

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14
Q

Homologous Structures

A

anatomical similarities in different organisms
example: vertebrate embryos all have: tail posterior to the anus, pharyngeal (throat) pouches

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15
Q

Evolutionary tree

A

representation of patterns of descent

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16
Q

Vestigial Structures

A

organs or anatomical structures that have been retained during evolution even though they have lost some of their ancestral functions
ex: whales have vestigial structures that show evidence that they came from 4 legged ancestor

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17
Q

Analogy

A

presence of similar structures in evolutionary divergent lines of descent, because of similar environmental pressure
ex: bats, birds, butterflies all developed wings from different environmental pressures

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18
Q

Divergence

A

two evolving groups of recent common ancestry becoming more dissimilar

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19
Q

Convergence

A

two evolving groups of distant common ancestry becoming more similar

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20
Q

The Fossil Record

A

chronicle of evolution over millions of years of geologic time engraved in order in which fossils appear in rock strata

(fossils: physical evidence of ancient organisms)

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21
Q

Biogeography

A

Study of where things are distributed all over the world
(ie how animals adapt to their environments)

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22
Q

Phylogeny

A

evolutionary history of an organism and its relationship to other species

mapped out with phylogenic trees

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23
Q

Phylogenic trees (and their parts)

branches, node, rooted, basal taxon, sister taxa

A

branching of diversification is depicted

derived characters are marked on branches
node: branches can be spun around
rooted: when the branch points of the tree represent the most recent common ancestor of all the taxa in the tree
basal taxon: lineage that diverges early on (not very close to the rest of the organisms on the tree)
sister taxa: groups of organisms that share an immediate common ancestor that is not shared by any other group

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24
Q

What can a phylogenic tree show you?

A

common ancestor, sequence of ancestral organisms leading to a particular taxon

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25
Q

What does a phylogenic tree not show?

A

does not show degrees of “closeness”, cannot infer the ages of taxa or branch points

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26
Q

Taxonomy

A

organization and classification of organisms

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27
Q

Binomial nomenclature

A

Formal system of naming species

Each species name formed out of latin and has two parts
* First part of the name (generic name) identifies the genus to which the species belongs
* Second part (specific name) distinguishes the species within the genus

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28
Q

Monophyletic group

A

group in which all of the individuals are more closely related to each other than any individuals outside of that group

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29
Q

Polyphyletic group

A

lack a direct link to a common ancestor, could have analogous characteristics due to environment

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30
Q

Paraphyletic

A

includes an ancestor and only some of its descendants

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31
Q

Outgroup

A

species from an evolutionary lineage that is closely related to, but not part of group of species of interest

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32
Q

Ingroup

A

species of interest

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33
Q

chronogram

A

phylogenic tree where the branch lengths are directly related to time (always an estimate)

34
Q

Maximum parsimony

A

an optimality criterion under which phylogenetic tree that minimizes total number of character-state changes

35
Q

Horizontal gene transfer

A

Process through which genes are transferred from one genome to another through mechanisms such as exchange of transposable elements, plasmids, viral infection and fusions

36
Q

Macroevolution

A

evolution on a big scale, long period of time

37
Q

Microevolution

A

small scale evolution, only a few gene changes (ex: dogs from wolves)

38
Q

Genetic variation

A

presence of differences in gene sequences between individual organisms of species
* allows for natural selection

39
Q

4 sources of Genetic Variation

A

1) formation of new alleles
* can arise from mutations
* germ-line: passed onto generations, mutation in sex cells
* somatic cells: mutation not passed to generations to come

2) Altering gene # and position
* chromosomal changes (delete, disrupt, rearrange <- deletion is most harmful)

3) Rapid reproduction
* mutations quickly generate genetic variation in prokaryotes due to quick lifespan

4) Sexual reproduction
* multiple ways offspring are different from their parents and siblings (crossing over, reassortment of homologies, alleles coming from 2 parents)

40
Q

Population

A

Group of individuals of same species that live in same area (relative) and interbreed, producing fertile offspring

must be natural (no populations that only exist in captivity)

41
Q

Gene pool

A

All copies of every type of alleles at every locus in all members of population

42
Q

Adaptive Evolution

A

traits that enhance survival or reproduction tend to increase in frequency over time
*ex: giraffe’s necks grew over time because the longer they were, the more fit they were (able to reach tall leaves)

43
Q

Genetic Drift

A

in small populations, by random chance alone, it is possible for allele frequencies to change from one generation to next

*ie allele frequencies will be different if change in population number occurs (lose half of population, chance of losing allele (that was rare already) is high))

44
Q

Fixation

A

genetic drift can lead to fixation for one allele or gene (allele is completely wiped out)

45
Q

Founder effect

A

(type of genetic drift): small number of individuals may leave population and become founding members of new isolated population

46
Q

Bottleneck effect

A

(type of genetic drift): a lot of parent population is wiped out and the surviving individuals have a different allele frequency

*ex: sea lions were hunted down to 30 which were only brown and white and thus those are the only existing colors today (used to have grey and black too)

47
Q

Gene flow

A

Transfer of alleles into or out of population due to movement of fertile individuals or their gametes

48
Q

Relative Fitness

A

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

  • Relative fitness = Absolute fitness / average fitness (average # of offspring)
49
Q

3 Modes of Natural Selection

A

1) Stabilizing: individuals with middle phenotype are selected (ex: infant birth weight)

2) Disruptive: Extreme phenotypes are favored (ex: finches with 2 sizes of beaks; middle size wont be able to eat small food or break hard food)

3) Directional: Either extremes (to the right or to the left) (ex: moths; when the trees turned black, it was better to be a black moth. When things got cleaner, the curve changed again because it was no longer good to be black)

50
Q

Balancing selection

A

preserving variation at some loci, therefore maintaining two or more phenotypic forms in population

51
Q

Heterozygote advantage

A

If individuals who are heterozygous at particular locus have greater fitness than do both kinds of homozygous

example: sickle cell gene
Aa: Resistant to malaria and only mild sickle cell disease
AA: susceptible to malaria but no sickle cell
aa: resistant to malaria but has fatal sickle cell disease

52
Q

Frequency-dependent selection

A

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

Example: warning coloration
In aposematic species (uses color to warn predators that they should not be eaten via venom, poison, etc.): predators are more likely to remember common color pattern that they have already encountered than one that is rare

53
Q

Sexual Selection

A

process in which individuals with certain inherited characteristics are more likely than other individuals of same sex to obtain mates

54
Q

Sexual dimorphism

A

differences in a secondary sexual characteristic between males and females of the same species (size, color, ornamentation, rituals)

55
Q

Intrasexual competition

A

individuals of one sex, usually males, gain competitive edge by fighting with each other. Winners claim the female

56
Q

Speciation

A

process by which one species splits into two species

57
Q

Species

A

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

58
Q

Biological Species Concept

A

Uses breeding behavior as basis for demarcating species

59
Q

Reproductive Isolation

A

existence of biological factors or barriers that impede members of two species from interbreeding and producing viable, fertile offspring

60
Q

Prezygotic Isolating Mechanisms

A

1) Habitat Isolation
* gene flow restricted because populations occupy different habitats of same area (ex: floor snakes and tree snakes)

2) Temporal Isolation
* mate at different times (ex: hawks (day) and owls (night), or pandas (only breed once a year))

3) Behavioral Isolation
* populations develop different courtship rituals that don’t attract outside populations (ex: bird dances)

4) Mechanical Isolation
* morphological or anatomical differences (sex organs do not fit each other)

5) Gamete Isolation
* biochemical or cellular differences (sperm is unable to fertilize the egg)

61
Q

Postzygotic Isolating Mechanisms

A

1) Reduced hybrid viability
* genes interact in ways that impair offsprings chances of survival (most hybrids do not complete development and are too weak to survive)

2) Reduced hybrid fertility
* hybrids may be sterile (ex: mules cannot interbreed)

3) Hybrid breakdown
* some hybrids survive but if they reproduce, the next generation is unable to survive (weak or sterile) (ex: ligers)

62
Q

Morphological species concept

A

method of classifying organisms into species based on their morphology (how similar they look)

63
Q

Ecological species concept

A

definition of species as set of organisms that is adapted to particular set of resources in environment (how an animal plays its role in the environment (ex: bees pollinating))

64
Q

Allopatric speciation

A

physical barriers will create new species

65
Q

Sympatric speciation

A

in the same area but still reproductively isolated. can occur if gene flow is reduced by:

a) polyploidy - extra set of chromosomes via mutation
b) habitat differentiation- subpopulation exploits habitat not used by parent population
c) sexual selection - mate choice based on male breeding coloration

66
Q

Hybrid zones

A

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

*Reinforcement: reinforcing reproductive barriers (natural selection should strengthen prezygotic barriers to reproduction)

*Fusion: two hybrid species fuse into a single species (mechanism keeping them separate was weak)

*Stability: hybrids continue to reproduce, sometimes because hybrids survive or reproduce better than members of either parent species

67
Q

Adaptive radiation

A

Organisms diversify rapidly from an ancestral species into multitude of new forms, particularly when change in environment makes new resources available (ex: extinction of dinosaurs)

68
Q

Colonization events

A

Colonizers find large number of opportunities for adaptation and diversification (like the founder effect)

69
Q

3 phenomena that led to adaptive radiation

A

1) mass extinction
2) colonization events
3) evolutionary innovations

70
Q

Heterochrony

A

evolutionary change in rate or timing of developmental events
ex: humans/chimps: genetic mutations in humans slowed growth of jaw relative to other parts of the skull

71
Q

Paedomorphosis

A

condition where sexually mature stage of species may retain body features that were juvenile structures in ancestral species

72
Q

Homeotic genes

A

genes that control patterns of body formation during early embryonic development of organisms

73
Q

Primates

A

mammals with 2 distinct features
1) grasping fingers and toes
2) binocular vision

74
Q

How long ago did primates split into two groups? What are those groups

A

40 million years ago

Prosimians & Anthropoids

75
Q

Prosimians

A

lemurs, tarsiers, lorises
* primitive, more reliant on smell (mark territory with scent), laterally places eyes, differences in reproductive physiology)

76
Q

Anthropoids

A

higher primates (monkeys, apes, humans)
* bigger; bigger brain, more parental care

77
Q

New world monkeys

A

wide range in size, diet, ecological adaptation
* almost exclusively living in trees

78
Q

Hominoids

A

apes hominids (humans and their direct ancestors)
* orangutans, gorillas, chimpanzees
* no tail
* longer infancy period

79
Q

Taxanomic rank (biological classification) ex: fox

A

DOMAIN (eukarya), KINGDOM (animalia), PHYLUM (chordata), CLASS (mammalia), ORDER (carnivora), FAMILY (candiae), GENUS (vulpes), SPECIES (vulpes vuples)

80
Q
A

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