Mcat Evolution

Front 1

Natural selection - What is fitness?

Back 1

Fitness is the ability for an organism to pass on its genes i.e. reproductive success

Front 2

An individual is strong, healthy, and lives long but does not reproduce. How would you define this person's fitness?

Back 2

Because this person cannot reproduce, he has a fitness of zero - as defined.

Front 3

Natural selection by differential reproduction.

Back 3

Individuals who reproduce more viable offspring are selected FOR.

Individuals who reproduce less viable offspring are selected AGAINST,

Front 4

Directional Selection

Back 4

Selects for an extreme trait.

I.e. selection for height of canopy trees - higher and higher

Front 5

Stabilizing selection

Back 5

Selects for a moderate trait, against the extremes.

I.e. birthweight - median weight favored over too low or too high weights.

Front 6

Disruptive selection

Back 6

Selects for either extreme.

Median trait is left out. One extreme trait is not favored over another.

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Group selection

Back 7

Natural selection that acts on a group rather than on just one individual

Explains why altruism exists - sacrifice individual fitness to benefit the group/family. When the benefit outweighs the cost, the altruistic behavior is selected for.

Front 8

Where can natural selection become apparent?

Back 8

An increase in the % representation in the gene pool of the next generation. Can also be present on an individual scale.

I.e. an increase in the frequency of an allele.

Front 9

What is a specie?

Back 9

3 conditions must be met for something to be considered a species:

1. Be able to interbreed
2. Be able to produce fertile, viable offspring
3. Does this naturally

Front 10

Speciation

Back 10

The formation of a new species that occurs due to barriers to successful interbreeding within an initial species.

Results due to competition

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Polymorphism

Back 11

Different forms of an allele trait

Front 12

Adaptation

Back 12

A genetic change in a population caused by natural selection.

Front 13

Specialization

Back 13

Adaptation of traits to better fill a niche

Occurs to better occupy a particular niche

Front 14

Niche

Back 14

What resources the species uses to survive in its environment.

Occupying different niches allows species to avoid competition and better use environmental resources

When niches overlap, there's competition

Front 15

Population growth vs. Competition

Back 15

Population growth is checked by competition

Front 16

Competition - when does it increase?

Back 16

When resources get scare, competition increases and thus, limits population growth.

Front 17

How does competition influence speciation?

Back 17

Competition within a species can force members of the species to occupy different niches, driving speciation.

Front 18

Inbreeding

Back 18

Mating between relatives

Decreases genetic diversity-increases homozygotes and decreases heterozygotes

Front 19

Wen would it be favorable to inbreed?

Back 19

Mole rats:

Stay in one small area & don't migrate much

Detrimental homozygous alleles are eliminated because of many generations of natural selection

Front 20

Outbreeding

Back 20

Mating between non-relatives

Increases heterozygosity

Front 21

Bottlenecks

Back 21

A severe reduction in population size

Can result from a natural disaster that wipes out a majority of the population

Increase the effect of genetic drift

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Genetic Drift

Back 22

A random change in allelic frequency

The effect of genetic drift increases as population size decreases

Front 23

Divergent evolution

Back 23

Start at the same lineage and evolve to become more different

Produces homologous structures

Front 24

Parallel evolution

Back 24

1. Same lineage
2. Similar traits
3. Evolved from similar mechanisms/mutations

Front 25

Convergent evolution

Back 25

1. Different lineage
2. Evolve closer together to become more similar
3. Evolve from different mechanisms/mutations

Front 26

Coevolution

Back 26

Two species evolve in response to each other

I.e. predator/prey host/parasite

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Ontogeny

Back 27

Development through the life of an organism

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Phylogeny

Back 28

Development throughout evolutionary time of a lineage/species

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Relationship between ontogeny and phylogeny

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Development of an organism repeats the evolutionary history of its species

I.e. Vertebrate embryos share features reminiscent of a common ancestor: gill slits, notochord, segmentation, paddle-like limbs

Front 30

The molecular clock theory

Back 30

A way to measure evolutionary time measured by gradual changes in the genome

Random genetic mutations - not resulting from natural selection

By measuring the amount of neutral mutations, you can find out how much time has passed

Able to compare genome difference b/w 2 species o find out how long ago they diverged

Front 31

Urey-Miller experiment

Back 31

Organic molecules created by atmospheric gases zapped by lightning

Front 32

RNA World Hypothesis

Back 32

Simple organic molecules formed RNA polymers that can self-replicate

Have intrinsic enzymatic activity

Front 33

Protocells

Back 33

Aggregates of RNA, proteins inside lipid envelopes

Front 34

Chordate

Back 34

Phylum in Anamalia kingdom

Features include:

Notochord, Pharyngeal pouches, Branchial arches, dorsal nerve cord

Front 35

Vertebrate

Back 35

Group under chordates (subphylum)

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Notochord

Back 36

the "backbone" of the embryo, except that it's not made of bone.

In vertebrates, bones will replace the notochord to form the vertebrae.

Front 37

Pharyngeal pouches, Branchial arches

Back 37

Pharangeal pouches, brachial arches)

= gill slits in the embryo.

Front 38

Dorsal nerve cord

Back 38

Forms the nervous system

In higher chordates, the nerve cord develops into the brain and spinal cord.

Front 39

Vertebrate Phylogeny

Back 39

Fish --> Jawless --> Bony + Cartilaginous --> Amphibians + Reptiles --> Mammals + Birds

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Jawless Fish

Back 40

Anatha: first jawless fist

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Cartilaginous fish

Back 41

(Condrichthyes/sharks/rays):
Then some developed jaws and a skeleton. Condrichthyes has a skeleton made of cartilage.

Front 42

Bony Fish

Back 42

(Osteichthyes/food fish):

Osteichthyes has a skeleton made of bone.

Front 43

Amphibians

Back 43

Bony Fish came onto land because their bony skeleton is strong enough to support their weight.

Front 44

Reptiles

Back 44

Can penetrate further onto land because they don't dry out like amphibians do. Similar to amphibians, the reptiles lay eggs.

Front 45

Mammals

Back 45

First to branch off from the reptiles.

Unlike the reptiles, mammals have milk glands, hair, and different tooth morphology (heterodontic).

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Birds

Back 46

Next to branch off from the reptiles.

Like the reptiles, birds lay eggs. (which came first, the chicken or the egg?

Ans: the egg, because the chicken is a bird, and reptiles laid eggs before birds even existed.)

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Types of natural selection

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1. directional
2. divergent
3. stabilizing
4. artificial
5. sexual
6. kin

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Kin selection

Back 48

1. animals live socially
2. sacrifice themselves for the sake of the alleles they share with others
3. ex: lioness sacrifices herself for her sister's children

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Reproductive isolation

Back 49

1. prezygotic barriers
2. postzygotic barriers

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Prezygotic barriers

Back 50

1. prevent formation of hybrid zygote
2. ecological (ex: river)
3. temporal (ex: different mating seasons)
4. mechanical (ex: Great Danes can't mate with Chihuahuas)
5. behavioral (ex: rituals)
6. gametic (ex: cat sperm can't fertilize dog egg)

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Postzygotic barriers

Back 51

Prevent development, survival, and reproduction of hybrids

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7 principal taxonomic categories

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1. kingdom
2. phylum
3. class
4. order
5. family
6. genus
7. species

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5 kingdoms

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1. monera
2. protista
3. fungi
4. plantae
5. animalia

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Cell walls in 5 kingdoms

Back 54

1. monera: peptidoglycan
2. protista: gram +/-, varied
3. fungi: chitin
4. plantae: cellulose
5. animalia: none

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Life cycle in 5 kingdoms

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1. monera: asexual/binary fission
2. protista: varied
3. fungi: sexual (multicellular form haploid)
4. plantae: sexual (haploid and diploid forms multicellular)
5. animalia: sexual (diploid forms muliticellular)

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Human: Kingdom

Back 56

Animalia

Front 57

Human: phylum

Back 57

1. chordata
2. have notochord/hollow dorsal nerve cord; gills slits in embryo

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Human: subphylum

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1. vertebrata
2. bilateral symmetry, cephalization, endoskeleton w/ vertebral column
3. 2/4 chambered heart, closed circulatory system
4. specialized organ systems

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Human: class

Back 59

1. mammalia
2. hair, 4 limbs, 4 chambered heart
3. mammary glands, internal fertilization, placental development

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Human: order

Back 60

1. primates
2. developed cortex, opposable thumbs, omnivorous, forward facing eyes

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Human: family

Back 61

1. hominidae
2. erect posture, intelligence, parental care for long periods

Front 62

Earth's early atmosphere

Back 62

1. reducing (no O2)
2. H2O, CO, CO2, N2
3. allowed for spontaneous synthesis of organic monomers
4. lightning, radioactive decay, volcano, Sun were sources of energy
5. formation of amino acids, carbs, lipids, and ribonucleotides

Front 63

RNA present in early world

Back 63

1. RNA chains form spontaneously
2. RNA chain self-replicate
3. RNA has catalytic activity

Front 64

Coacervate

Back 64

1. complex particle that includes polypeptides, nucleic acids, nucleic aids, and poly-saccharides

Front 65

Protobionts

Back 65

1. resemble cells in that they contain a protected inner environment and perform chemical reactions
2. lack organized mechanism of heredity