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Evolution Flashcards

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1
Q

What is evolution?

A

-Decent with modification
- The change in genetic composition from one generation to the next
- A pattern and a process
- observations about the natural world (facts, data)
- Mechanisms that cause the observed pattern of change

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2
Q

What is the genetic bases of evolution?

A

-Decent from a common ancestor evidence

  • common macromolecules (DNA,RNA, Proteins)
  • Common molecules (20 amino acids, 4 nucleotide bases)
  • Common mechanisms for DNA replication
    -Common metabolic pathways
    -Common genetic code
    -Similarity in form
    -Fossil record
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3
Q

What are the three domains of life?

A

Archaea, Bacteria, Eukaryotes

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4
Q

What unites archaea and bacteria?

A

They are both prokaryotes

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5
Q

What unites archaea and eukaryotes?

A
  • Components of DNA replication, transcription and translation
    -30+ ribosomal proteins shared that are absent in bacteria
    -translation factors
    -RNA polymerase more similar then between archaea and eukaryotes
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6
Q

What are the characteristics of archaea, bacteria and eukaryotes?

A

Archaea
- Single cell microbes
- can use a variety of energy sources
- live in extreme environments
- identified as a separate domain based on rRNA genes

Bacteria
- single celled microbes distinct from archaea
- live in most of earth’s habitats

Eukaryotes
- Everything that’s not archaea or bacteria

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7
Q

What are phylogenetic trees?

A

A diagram that shows the evolutionary relationship between species based on physical or genetic similarities and differences

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8
Q

How do you interpret phylogenetic trees?

A
  • Root of the branch: the ancestral linages
  • Tips of the branches: descendants of that ancestor
  • As you move from the root to the tip you move forward in time
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9
Q

What is a clade?

A

A group that included a common ancestor and all its descendants (living or extinct)

Clades are nested within each other

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10
Q

What are the two parts of evolution and their characteristics?

A

Anagenesis: the change in a lineage over time
- Rare, phyletic changes

Cladogenesis: the splitting of one lineage into two (speciation)
- A single ancestral lineage gives rise to two or more daughter lineages
- common, promote biological diversity

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11
Q

What are the four basic ideas of evolution by natural selection?

A

Variation: Individuals within a population are variable traits, traits vary among individuals

Inheritance: The variation in individuals are passed down genetically from parents to offspring

Exponential growth: All species produce more offspring than their environment can support

Differential success: Some traits create and advantage for survival or reproduction, this leaving more offspring
- the individuals with the most favored variants are selected for because they have a higher chance of survival and thus leave more offspring

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12
Q

What are some observations Darwin made on his voyage on The Beagle (1831-1836)?

A
  • Noted that species in S. America (tropics) more closely resembled those in Africa rather than species in Europe
  • Fossils resembled each other
    -Found fossils of ocean organisms in Andes mountains
    -On the Galapagos:
    • Finches: observed there had to be a common ancestor from which they evolved from based on the food available (adaption arise from natural selection)
    • Mockingbirds were unique to each island
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13
Q

Who was Carl Linnaeus (1707-1778) and how did his work influence Charles Darwin?

A
  • modern classification system (Genus and species) (Latin binomial)
  • Realized there was some association between species (classification)

Species - genus - family - order - class - phylum - kingdom - domain

  • Led to the development of Darwin’s research to gain an understanding of how organisms can be related
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14
Q

Who was Georges-Louis Leclerc (1707-1788) and how did he influence Charles Darwin?

A
  • Studied biogeography, noticed that have similar environments had similar but unique wildlife
  • hypothesized that specie changed as time passed
    -entertained the idea of evolution and though the earth might be old
  • Influenced Darwin’s through his incorporation of lost species which Darwin studies and then related to fossil evidence
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15
Q

Who was Jean Baptiste Lamarck (1744-1829) and how did he influence Charles Darwin?

A

-Developed a mechanism from evolution → Inheritance through acquired traits/characteristics (in Giraffe necks)
- Use and disuse: Parts of the body that are repeatedly used become larger and stronger can be passed down

  • His ideas inspire Darwin’s ideas on natural selection and Inheritance
    -He thought that variation was introduced by inheritance if acquired characteristics
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16
Q

Who was Thomas Robert Malthus (1766-1834) and how did he influence Charles Darwin?

A
  • Population multiplies geometrically and food arithmetically (elephants)
  • Population grows exponentially

(But there is a cap population that can be sustained by the environment)

-Darwin reasoned out the idea of competition within a population
- More individuals are born than can survive: Excessive Reproduction and Differential Success

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17
Q

Who was Charles Lyell (1797-1875) and how did he influence Charles Darwin?

A
  • Principles of Geology/ Uniformitarianism→ states that geological processes have not changed throughout Earth’s History (geologist→ earthquakes)
    -The layers of sedimentary rock (strata) in which fossils can be found show a timeline

Helped Darwin isolate other variables in Darwin’s theory which could help him better understand evolution and natural selection

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18
Q

Who was Alfred Wallace?

A
  • traveled in S. East Asia (Malay Archipelago)
  • Had similar findings with Darwin
  • Published together with Charles Darwin
  • The next year The Origins of Species was published
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19
Q

What is the mechanism for evolution Charles Darwin Came up with?

A

1) Variation among individuals
2) Variation is passed from parent to offspring
3) More individuals are born than can survive
4) Some variants survive and reproduce at a higher rate than others
5) Outcome: The population changes from one generation to the next

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20
Q

What is some info Charles Darwin use to build an argument for evolution?

A
  • Selection under domestication (horses, dogs, pigeons)
  • Biogeography: Closely related specie occur in the same geographic area
  • Fossil record: New groups don’t appear at once but in succession
  • consistent with Linnaean system of classification: hierarchal classification simply reflects varying degrees of relatedness
  • Homology: Similarity of structure in different species often used for different purposes
    • similarities in development and on molecular level
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21
Q

What are homologous structures?

A

Human arm, Cat leg, whale fin, bat wings → have similar bone structures (doesn’t need to have a common function)

Demonstrate that a common ancestor needs to have existed to unite them

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22
Q

What are vestigial structures?

A

had a function in their ancestors → snakes have vestiges of the pelvis and legs of ancestors

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23
Q

What are vestigial structures?

A

had a function in their ancestors → snakes have vestiges of the pelvis and legs of ancestors

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24
Q

What is convergence evolution?

A
  • Independent evolution of similar feature in different lineages
  • Adapt to similar environments in similar ways → Similarities are analogous
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25
Q

What is population genetics?

A

approach to understand microevolution that combines mathematical theory and experimental data to understand the effects of mutation, genetic drift and natural selection on genes within a population

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26
Q

What is a population?

A

A group of interbreeding individuals that belong to the same species and occupy a similar geographical area

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27
Q

What is Genetic variation?

A

Differences among individuals in the composition of their genes or DNA sequences

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28
Q

What are Alleles?

A

alternative versions of genes that differ in nucleotide sequences → different alleles may produce differences in characteristics

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29
Q

What is a gene?

A

A section of a DNA strand (sequence of nucleotides) that determines the sequence of amino acids in the protein for which it encodes

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30
Q

What is phenotype?

A

physical appearance of a given genotype in a given environment

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31
Q

What is the gene pool?

A

All the copies of every allele type at every locus in all members of a population

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32
Q

What is fixation?

A

An allele is said to be fixed in the gene pool if only one allele exist for a particular locus in a population (all individuals are homozygous for that allele)

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33
Q

What mechanisms can cause the evolution of a population?

A

1) Natural selection:(acts on individuals and therefore populations)
- Individuals that have traits that are favorable within their environment survive and reproduce more than those with less favorable traits

2) Genetic Drift: random changes in allele or genotype frequencies within a population

3) Mutations: a change in the nucleotide sequence of a gene in an individual

4) Gene Flow: the movement of genes among populations due to migration and inbreeding

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34
Q

What are the types of evolution?

A

Microevolution: evolution within a population, over a shorter timescale than macroevolution

Macroevolution: evolution across geological timescales (generally millions of years), involving groups of species

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35
Q

What is the Hardy Weinberg model?

A
  • Used to test whether a population is evolving by calculating what the allele and genotype frequencies would be if the population isn’t evolving (compare expected and observed values)
  • considers the combination of all alleles in all of the crosses in a population
    • Frequency of Alleles; AA= 64% , Aa=32% , aa=4%
36
Q

What are the conditions for Hardy Weinberg Equilibrium?

A
  • No mutation - if mutations occur the gene pool is modified
  • Random mating- If there is random mating, the mixing of gametes does NOT occur therefore affecting the frequency of homozygous and heterozygous genotype (doesn’t effect allele frequency)
  • No Natural Selection: If there is natural selection , allele frequencies change when individuals with different genotypes show consistent differences in their survival or reproduction
  • Extremely large population: If the population is small, allele frequencies fluctuate by chance over time (Genetic drift)
  • No gene flow: If there is gene flow, the movement of alleles in and out of the population can alter allele frequencies
37
Q

What are the four forces of evolution?

A
  • mutation
  • natural selection
  • genetic drift
  • gene flow
38
Q

What functions do mutations play in changing the allele frequencies within a population ?

A
  • They create variation
  • Point mutation: A change in a single nucleotide (EX: Sickle cell)
    - Natural selection can quickly remove harmful alleles since they are slow or they can be hidden from selection (heterozygous protection)
    -More mutations can come from fathers because they use stem cells to make sperm while women are born with all they eggs they will ovulate
  • Chromosomal mutation: Chromosomes are rearranged, duplicated, or lost (Down syndrome)
  • Whole genome duplication (in many plants)
39
Q

What is fitness?

A

The contribution of an individual to the gene pool of the next generation, relative to other individuals

Depends on the environment/ Phenotype (and by extension the genotype)

40
Q

What are the three types of selection in phenotype and their characteristics?

A
  • Directional selection: When conditions favor individuals exhibiting an extreme of a phenotypic range
    - common when population’s environment changes or members of a population migrate
  • Disruptive selection: Conditions favor individuals at both extremes of a phenotypic range over individuals in the intermediate phenotypes
  • Stabilizing selection: Act against extreme phenotypes, favors the intermediate phenotypes
    - Reduces variation
41
Q

What are the three types of selection in genotypes and their characteristics?

A
  • Positive directional selection: one allele results in higher rates of survival and reproduction → new beneficial mutation that is increasing in frequency (allele may go to fixation)
  • Purifying selection: elimination of harmful alleles → mutation is harmful, selection is trying to eliminate it
  • Balancing selection: Aa (Heterozygotes) have higher fitness than homozygote → EX Sickle Cell
42
Q

What are the three types of selection in genotypes and their characteristics?

A
  • Positive directional selection: one allele results in higher rates of survival and reproduction → new beneficial mutation that is increasing in frequency (allele may go to fixation)
  • Purifying selection: elimination of harmful alleles → mutation is harmful, selection is trying to eliminate it
  • Balancing selection: Aa (Heterozygotes) have higher fitness than homozygote → EX Sickle Cell
43
Q

What is directional selection?

A

Selection of phenotype

When conditions favor individuals exhibiting an extreme of a phenotypic range

common when population’s environment changes or members of a pop. migrate

44
Q

What is Disruptive Selection ?

A

Selection of phenotype

Conditions favor individuals at both extremes of a phenotypic range over individuals in the intermediate phenotypes

45
Q

What is Stabilizing Selection ?

A

Selection of phenotype

Act against extreme phenotypes, favors the intermediate phenotypes

reduces variation

46
Q

What is Positive directional selection?

A

Genotype selection

one allele results in higher rates of survival and reproduction → new beneficial mutation that is increasing in frequency (allele may go to fixation)

47
Q

What is Purifying selection?

A

Genotype selection

elimination of harmful alleles → mutation is harmful, selection is trying to eliminate it

48
Q

What is sexual selection?

A

individuals with certain inherited characteristics are more likely than others of the same sex to obtain mates

can result in sexual dimorphism → difference in sexual characteristics between males and females of the same species

49
Q

What are the two types of sexual selection?

A
  • Intra sexual selection: Competition among individuals of one sex
  • Inter sexual selection: Mate choice by the opposite sex
50
Q

What are the two types of sexual selection?

A
  • Intra sexual selection: Competition among individuals of one sex
  • Inter sexual selection: Mate choice by the opposite sex
51
Q

What is the good genes model?

A

Females prefer males with certain traits because they are associated with good genes

52
Q

What is Fisher’s runaway model?

A

Females prefer mates with extreme traits which will give rise to sons with extreme traits and daughters that prefer those extreme traits

53
Q

What is genetic drift?

A

Chance events that cause allele frequencies to fluctuate unpredictably from one generation to the next (occurs especially in small populations)

Circumstances that result in a significant impact on a population → Founder effect/ bottleneck effect

Leads to certain alleles being over represented →Loss of genetic variation and increase in frequency of harmful alleles

54
Q

What is the founder effect?

A

When a few individuals are isolate from a large pop. and may establish a new population whose gene pool differs

Certain alleles may be over represented →Loss of genetic variation and increase in frequency of harmful alleles

55
Q

What is the bottleneck effect?

A

a sudden change in environment which causes a severe drop in population

Certain alleles may be over represented →Loss of genetic variation and increase in frequency of harmful alleles

56
Q

What are the effects of Genetic drift?

A
  • Significant in small populations- chance events will alter allele frequencies substantially
  • Can cause allele frequencies to change at random
  • Can lead to loss of genetic variation within a population
  • Can cause harmful alleles to become fixed
57
Q

What is gene flow?

A

The transfer of alleles into or out of a population due to movement of fertile individuals or their gametes

Tends to reduce genetic differences between populations

Can affect how well populations are adapted to their local environments (for better or worse)

58
Q

Why can’t natural selection make a perfect organism?

A
  • Selection can only act on existing variations →It only favors the fittest phenotype present in the population
  • Evolution is limited by historical constraints → existing structures are adapted to new situations, they can NOT be built from scratch
  • Adaptions are often compromises → ability to perform one function may reduce the ability to perform another
  • Chance, natural selection and the environment interact
59
Q

Why does sexual selection occur?

A
  • Reproductive success
  • Females usually invest more time and effort into offspring than males do
  • Most populations contain an over abundance of males that compete for access to a limited number of reproductively active females
    Females become a limiting resource for reproduction
60
Q

What are the three phylogenetic groups?

A
  • Monophyletic groups (clade): A group containing an ancestral species and ALL of its descendants
  • Paraphyletic groups: A group containing some but NOT ALL of its descendants
  • Polyphyletic groups: A group that contains distantly related species but not their most recent common ancestor
61
Q

What is a monophyletic group?

A

A clade

A group containing an ancestral species and ALL of its descendants

61
Q

What is a monophyletic group?

A

A clade

A group containing an ancestral species and ALL of its descendants

62
Q

What is a paraphyletic group

A

A group containing some but NOT ALL of its descendants

63
Q

What is a polyphyletic groups?

A

A group that contains distantly related species but not their most recent common ancestor

64
Q

How are the correct relationships among a set of taxa determined?

A

Homologous characters that are shared among a set of taxa

  • Homology: Similarities due to shared ancestry
  • Analogy: Similarities due to convergent evolution (traits that evolved independently in each group)
65
Q

What is Homology?

A

Similarities due to shared ancestry

66
Q

What is analogy?

A

Similarities due to convergent evolution (traits that evolved independently in each group)

67
Q

What is parsimony?

A

a hypothesis of relationships that requires the smallest number of character changes is most likely to be correct

68
Q

What are Synapomorphies?

A

an ancestral character or a trait that is shared by different two or more taxa

69
Q

What is polytomy?

A

a section of a phylogeny in which the evolutionary relationships can not be fully resolved to dichotomies. In a phylogenetic tree, a polytomy is represented as a node which has more than two immediate descending branches.

69
Q

What is polytomy?

A

a section of a phylogeny in which the evolutionary relationships can not be fully resolved to dichotomies. In a phylogenetic tree, a polytomy is represented as a node which has more than two immediate descending branches.

70
Q

How does reproductive isolation arise?

A
  • Due to barriers to gene flow
    - Gene flow: the movement of genes among populations due to migration and inbreeding
71
Q

What is geographic isolation?

A
  • reproductive isolation
  • Pre-zygotic barrier to gene flow
  • the species may occupy different geographic areas and not encounter each other
72
Q

What is habitat isolation?

A
  • reproductive isolation/ pre mating
  • Pre-zygotic barrier to gene flow

-species may occupy different habitats within the same area

EX: Two species of crickets in the eastern US co-occur in some places but one prefers loamy soil while the other prefers sandy soil

73
Q

What is Temporal isolation?

A
  • reproductive isolation/ pre mating
  • Pre-zygotic barrier to gene flow

-The species may breed at different times of the day, year, or in different years

EX: Some species of Cicadas in the Eastern US are isolate because they breed in different multiyear cycles (once every 13 years and once every 17 years)

74
Q

What is Behavior (mating) isolation?

A
  • reproductive isolation/ pre mating
  • Pre-zygotic barrier to gene flow

-closely related species may differ in behaviors that attract mates

EX: Different courtship songs in fruit flies

75
Q

What is Mechanical isolation?

A
  • reproductive isolation/ post mating
  • Pre-zygotic barrier to gene flow

-the inhibition of fertilization between two species due to mechanical differences in reproductive structures

EX: Genitalia of many different species evolve rapidly, such that genitalia of males and females of different species do NOT fit properly

76
Q

What is Gametic isolation?

A
  • reproductive isolation/ post mating
  • Pre-zygotic barrier to gene flow

Sperm of one species may not be able to fertilize the eggs of another species

EX: Sea urchins release gametes into the water do not bind properly to the eggs of another closely related species

77
Q

What is Gametic isolation?

A
  • reproductive isolation/ post mating
  • Pre-zygotic barrier to gene flow

Sperm of one species may not be able to fertilize the eggs of another species

EX: Sea urchins release gametes into the water do not bind properly to the eggs of another closely related species

78
Q

What are the three post-zygotic barriers to gene flow?

A

Hybrid inviability
Hybrid sterility
Hybrid breakdown

79
Q

What is Hybrid inviability?

A

First generation hybrids are formed but have lower fitness, either due to a poor fit to the environment or due to developmental problems

EX: Larvae do not survive to become adults

80
Q

What is Hybrid sterility?

A

First generation hybrids are formed and are fully viable but are either sterile or have reduced fertility

EX: the cross between a horse and a donkey is a mule which is sterile

81
Q

What is Hybrid sterility?

A

First generation hybrids are formed and are fully viable but are either sterile or have reduced fertility

EX: the cross between a horse and a donkey is a mule which is sterile

82
Q

What is Hybrid breakdown?

A

First generation hybrids are formed and are viable and fertile but their offspring have reduced viability of fertility

EX: Seen in crosses between some species of house mice

83
Q

What is Haldane’s Rule?

A

When there is a cross between two species the offspring sterility/inviability is seen in only the sex with DIFFERENT sex chromosomes

-How did hybrid sterility evolve?

  • Problem: It could not have been due to a single gene because then there would be AA, aa and Aa (sterile) genotypes. This means that Aa would never become fixed so the offspring of the cross between the two species wouldn’t always be sterile
  • Solution: Dobzhansky-Muller model → Reproductive isolation is caused by multiple interacting genes (epistasis) AABB → aaBB or AAbb → AaBb is sterile because a and b would not work together

EX: In mammals it always the males that are sterile or inviable (males have an x and a Y chromosome; females have two x chromosomes)

84
Q

What is speciation? And what are the three geographical modes of speciation?

A

the formation of new and distinct species in the course of evolution.

  • Allopatric Speciation: Complete geographic isolation meaning no gene flow
  • Parapatric Speciation: Selection is necessary to overcome the potential of gene flow (no gene flow because it is selected against)
  • Sympatric Speciation: Selection is necessary to overcome the potential of gene flow (no gene flow because it is selected against) OR polyploidization
       - Speciation by polyploidy (mostly in plants) → INSTANT SPECIATION

        - Autopolyploid speciation occurs when an individual arise from two diploid gametes from a single species 
     - Failure of cell division after chromosome duplication gives rise to tetraploid (extra chromosome sets)
85
Q

What happens when two species that are partially isolated come into contact?

A
  • Hybrid Zones can form
  • Reinforcement can sometime occur → this is the strengthening of mating isolation in response to selection against unfit hybrids

Biology 1B (3 decks)

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