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EVOLUTION > EXAM 3 FALSHCARDS > Flashcards

EXAM 3 FALSHCARDS Flashcards

1
Q

what is LUCA

A

Last Universal Common Ancestor (common ancestor of ALL living things)
- NOT THE FIRST LIVING THING

- There was a pool of living things where some were good at surviving and some were not. LUCA survived and gave rise to ALL life on this planet
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2
Q

approximately when do we think LUCA originated

A

~ 3.8 billion years ago
(LUCA does not mean 1st living thing)

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3
Q

how is LUCA a phylogenetic event horizon

A

phylogenetic event horizon: it is the point in the history of life beyond which phylogenetic analysis can NOT see.
- In terms of LUCA we can NOT see beyond LUCA because we don’t know what happened before LUCA (there is no real evidence)

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4
Q

what are the characteristics of living things

A
  1. metabolism/energy processing
  2. maintain homeostasis
  3. respond to environment
  4. growth and development
  5. reproduction
  6. hereditary (passing along genes)
  7. order/cellular organization
  8. evolution
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5
Q

what are the essential elements of life

A
  1. Carbon
  2. Hydrogen
  3. Oxygen
  4. Nitrogen
  5. Phosphorus
  6. Sulfur
  • there are others, but these are the MAJOR ones
  • make up things like carbohydrates, proteins, lipids, and nucleic acids = building blocks of life
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6
Q

what are the building blocks of life

A
  1. Nucleic acid = hereditary material, mRNA, ribosomes, tRNA
  2. Carbohydrate = structural elements as well as important energy storing molecules
  3. Lipids = structural elements as well as signaling molecules
  4. Protein = “molecule of life”, diff proteins have diff function
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7
Q

what is the Oparin-Haldane hypothesis

A

1920’s Aleksandr Oparin and J.B.S. Haldane formalized the “warm little pool” idea proposing abiogenesis from a prebiotic soup

  1. Formation of biomolecules: in an atmosphere that lacked oxygen, UV light, and lightning could have served as energy sources that converted atmospheric gasses into biomolecules that served as early basis of life
  2. Formation of molecules that could function as enzymes and hereditary information (we needed ways to store information and pass it along, we also needed proteins or enzymes and some sort of mechanism for replicating that hereditary info)
  3. Formation of protocells containing the above and surrounded by semi-permeable membrane
  • Protocells are pre cells that had to have some way of compartmentalizing itself from outside world. proposed that membrane would have also been one of the first things necessary in order to form a cell

(evidence for this “prebiotic soup” = Miller Urey experiment)

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8
Q

What components/characteristics are hypothesized to have been in “protocell”?

A
  1. control flow of nutrients in and out across boundary layer (membrane) (NEEDS MEMBRANE)
  2. Genetic material that can be replicated/passed down
  3. Ability to divide and form daughter cells

(THESE WOULD HAVE BEEN THE 3 MINIMUM REQUIREMENTS FOR A CELL TO BE SUCCESSFUL AND ULTIMATELY PROLIFERATE ACROSS PLANET)

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9
Q

what was the Miller Urey experiments and what was its significance

A

1953: Stanley Miller and Harold Urey were trying to replicate what we thought was the early Earth’s atmosphere, temps, etc. and see if they could somehow cause the building blocks of life to form if they could simulate what happened

  1. Tested the plausibility of abiogenesis from a prebiotic soup
  2. Mixture of gasses (methane, hydrogen, ammonia) + spark from electric current
    • Simulated reducing atmosphere and energy source

FOUND: DEPENDING ON GASSES USED, DIFFERENT AMINO ACIDS PRODUCED

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10
Q

In the lecture, a video of a student replicating the Miller Urey experiment was shown. What was found?

A

The video in the lecture conducting the same experiment, found that you can not only form amino acids but by introducing this external molecule called cyanamide, this can cause amino acids to link together and form larger components such as polypeptides

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11
Q

what is the cell theory and 6 key points

A

“all living things are made of cells”
1. the cell is the fundamental unit of structure and function in living things
2. all organisms are made up of one or more cells
3. cells arise from other cells through cell division
4. cells carry genetic material passed to daughter cells during cellular division
5. all cells are essentially the same in chemical composition
6. energy flow (metabolism and biochemistry) occurs within cells

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12
Q

first life on this planet probably looked very similar to? what do these cells contain

A

Prokaryotes: containing membrane, hereditary material, and some mechanism to replicate that hereditary material

  1. cell wall
  2. cell membrane
  3. ribosome
  4. plasmids
  5. cytoplasm
  6. large circular DNA molecule
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13
Q

what is abiogenesis

A
  1. chemical formation of life from nonliving material
    • (life arose spontaneously from simple chemical compounds such as (water = H2O, methane = CH4, hydrogen sulfide = H2S, and ammonia = NH3)
  2. From those simple chemical compounds, there were reactions that formed smaller or a little bit bigger molecules leading to those compounds coming together to form larger molecules that were the building blocks of life
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14
Q

what was Charles Darwin’s “warm little pond” idea

A

might have been one of the first to suggest idea of abiogenesis

  1. In an 1871 letter Darwin suggested that simple inorganic molecules could be transformed into cell building blocks in a “warm little pond, with all sorts of ammonia and phosphoric salts, lights, heat, electricity, etc. present, so that a protein compound was chemically formed ready to undergo still more complex changes”
  2. where everything was able to react and come together
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15
Q

what is the first step to forming a cell compartment

A

cell membrane

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16
Q

what idea provides an explanation for origin of cell membranes

A

the idea of soap and water working together to clean a dirty, greasy pan

  1. Soap molecules have hydrophilic head and hydrophobic tail. When soap is placed in water, the soap molecules self assemble into little bubbles (micelles). The grease hooks onto the hydrophobic (water hating tail) sides of soap molecules and these hydrophobic tails surround grease while the hydrophilic parts are washed away by us
  2. Soap molecules are similar to phospholipids which are the building blocks of a cell membrane and they are amphiphilic (contain hydrophobic and hydrophilic end)
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17
Q

what idea provides an explanation for origin of genetic material

A

the chicken and egg…which came first nucleic acids or proteins?

  1. In modern cells DNA and RNA encode information to make proteins
  2. Proteins are necessary to replicate DNA and transcribe RNA
  3. Discovery of ribozymes by Thomas Cech and Sidney Altman
    • RNA molecule that can act as an enzyme (RNA enzyme that is needed to catalyze creation of DNA/RNA/proteins)
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18
Q

what is the RNA world hypothesis

A
  1. The idea that early life might have been RNA-based instead of DNA-based
    • Instead of DNA being the genetic code in our early cells, maybe it was RNA (which is possible given the discovery of ribozymes)
  2. Possible because RNA was a genetic transmission system as well as an enzyme that catalyzed biological reactions (such as replication of genetic transmission system)
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19
Q

what is evidence for RNA world

A
  1. Many enzyme cofactors (molecules that help enzymes to work properly) are RNA-based
  2. Deoxyribonucleotides are constructed in cells first by making ribonucleotide, then removing hydroxyl (OH) group
  3. Catalytic site of ribosome is made of RNA (ribosome is essentially a ribozyme)
  4. All essential parts of RNA likely existed in prebiotic world
  5. RNA is critical to all stages of protein synthesis (mRNA…rRNA…tRNA)
    • Transcription process when we build messenger RNA and then translation process we get 3 different types of RNA involved in producing protein
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20
Q

why is DNA likely favored over RNA for the genetic code by natural selection

A
  1. DNA is less error prone
  2. DNA has lower mutation rates meaning genes can get longer and DNA could pass on more information than RNA to next generation
  3. DNA is less reactive (harder to break apart)
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21
Q

what are the negatives of RNA

A
  1. unstable molecule because of ribose (with extra O) is more reactive (breaks apart easily) than deoxyribose
  2. Single-stranded with potential to interact with other molecules/disrupt code
  3. NO proofreading
  4. NO repair mechanisms
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22
Q

what happened 4.6 bya?

A

our solar system is a cloud of dust and gas (solar nebula) -> big bang

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23
Q

what happened 4.5 bya

A

earth forms (4,000°C) - > HOT

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24
Q

what happened 4.2 bya

A

first ocean / prebiotic RNA world (160°C and 0% ATMOSPHERIC OXYGEN)

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25
Q

what happened 3.8 bya

A

first life on Earth / LUCA (1st life not necessarily LUCA) / DNA WORLD

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26
Q

what happened 3.2 bya

A

first photosynthesis / banded iron formation / 1st continent (Vaalbarra)

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27
Q

what happened 2.4 bya

A

great oxygenation event / mass extinction

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28
Q

what happened 2 bya

A

first eukaryotes / mitochondria / complex symbiosis

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29
Q

what happened 1.1 bya

A

first multicellular organisms / fungi / Rodinia (supercontinent)

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30
Q

what happened 600 mya

A

first animals (metazoa / bilaterians (heads and tails)

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31
Q

what happened 6-7 mya

A

first hominins (human like creatures) / mammoths / megalodons

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32
Q

what happened 300,000 ya

A

first homo sapiens (humans) / cultural evolution / industrial revolution / anthropocene (greenhouse event)

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33
Q

what are the sources of elements/molecules in “prebiotic soup”

A
  1. meteorites with
    • carbon, lipids, amino acids, nucleobases, ribose
    • amphiphilic molecules that assemble into vesicles
    • phosphorus

2.Deep sea hydrothermal vents (brought up nutrients from inside of the Earth
3. Interstellar ice “raining” down (providing water and ultimately helping to populate our ocean with more water

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34
Q

what is a micelle

A

self-assembling spherical-shaped grouping of amphiphilic molecules (contains hydrophobic and hydrophilic end) contained in a liquid

  • Protocell might have had a simple membrane composed of self-assembling fatty acids or maybe even phospholipids we don’t know for sure but either way that’s probably what happened
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35
Q

what is an amphiphilic molecule

A

molecule that contains a hydrophobic (water hater) end and hydrophilic (water loving) end

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36
Q

what is a ribozyme

A

RNA molecule that can act as an enzyme (RNA enzyme)
- could be both information carries and enzymatic molecules

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37
Q

LUCA is considered a phylogenetic event horizon because
A. It is only found within a black hole
B. It is a phylogeny based on extinct species
C. It is a point in the history of life beyond which phylogenetic analysis cannot see
D. It is the point at which life started
E. It is a point in the future when species will diversify

A

C. It is a point in the history of life beyond which phylogenetic analysis cannot see

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38
Q

When life first evolved, ocean temperatures were ________ and there was ________ atmospheric oxygen.

A. Hotter; no
B. Cooler; abundant
C. Cooler; no
D. Hotter; abundant

A

A. Hotter; no

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39
Q

Which of the following is the best explanation of the term “abiogenesis”?

A. Idea that life on Earth arrived on asteroids from other planets
B. Idea that life on Earth arose spontaneously from chemicals present
C. Idea that life arose through intelligent design

A

B. Idea that life on Earth arose spontaneously from chemicals present

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40
Q

The Oparin-Haldane hypothesis suggested (CHECK ALL THAT APPLY)

A. The first cells were able to exchange hereditary material with each other

B. The first cells were surrounded by a membrane

C. The first life had molecules that could function hereditary information

D. Biomolecules arose spontaneously in a prebiotic soup

A

B. The first cells were surrounded by a membrane

C. The first life had molecules that could function hereditary information

D. Biomolecules arose spontaneously in a prebiotic soup

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41
Q

The Miller–Urey experiment is significant because it produced the first scientific evidence that

A. It is possible to produce DNA under the same conditions as on Earth 4 billion years ago

B. Micelles spontaneously form in aqueous solution

C. It is possible to produce LUCA in the laboratory

D. The hypothesized conditions on Earth 4 billion years ago could produce RNA

E. The hypothesized conditions on Earth 4 billion years ago could produce amino acids

A

E. The hypothesized conditions on Earth 4 billion years ago could produce amino acids

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42
Q

These more recent experiments showed that introducing cyanamide into the mix of the M-U samples caused:

A. Polysaccharides to form
B. Phospholipids to form micelles
C. New amino acids to form
D. Amino acids to link together into polypeptides
E. Triglycerides to form

A

D. Amino acids to link together into polypeptides

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43
Q

What is the main structural component that forms the cell membrane’s double layer?

A. Polysaccharides
B. Phospholipids
C. Amino acids
D. triglycerides

A

B. Phospholipids

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44
Q

What is meant by the term “hydrophobic”

A. Repels water
B. Attracts water
C. Polar
D. charged

A

A. Repels water

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45
Q

How did the discovery of ribozymes affect our understanding of the evolution of proteins and nucleic acids?

A. The discovery of ribozymes helped us understand that DNA must have come before proteins

B. The discovery of ribozymes demonstrated definitively that ribozymes that function only as enzymatic molecules and therefore evolved before information carrier molecules

C. The discovery showed that ribozymes could be both information carries and enzymatic molecules

D. The discovery of ribozymes demonstrated that proteins must have originated before DNA

A

C. The discovery showed that ribozymes could be both information carries and enzymatic molecules

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46
Q

Which of the following is a reason natural selection favored DNA over RNA as genetic material?

A. RNA is less stable because ribose is more reactive

B. DNA has higher mutation rates than RNA

C. DNA can self-replicate

D. DNA has more nitrogenous base “letters” than RNA

E. All of the above are reasons that DNA was favored over RNA as genetic material

A

A. RNA is less stable because ribose is more reactive

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47
Q

when did life on Earth most likely originate?

A

~ 3.8 bya

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48
Q

when did “early earth” originate and what is important to note about it?

A

~4.5 bya
1. NO LIFE
2. Simple chemical compounds like water (H2O), methane (CH4), hydrogen sulfide (H2S), and ammonia (NH3)
3. planet was much HOTTER and the oxygen content of the atmosphere was NON-EXISTENT at this time

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49
Q

what occurred 66 mya

A

Cretaceous - Pasogene (Cretacious - Tertiary) Extinction / asteroid impact / global winter / mass extinction

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50
Q

what is a “prebiotic soup”

A

a hypothetical early Earth environment where simple inorganic molecules like methane, ammonia, and water vapor are present in a reducing atmosphere and reacted with energy from sources like lightning to form the first organic compounds, creating a pool of building blocks for life
- “soup” of organic molecules that could eventually lead to the development of living organisms

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51
Q

what is the definition of a major evolutionary transition (MET)

A

watershed events (period of time that represent big change) in the history of life

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52
Q

what are METS characterized by

A
  1. Formation of a cooperative group of individuals
  2. Over time, transformation of the cooperative group to a cohesive, higher level of individual (within the new cohesive individual, the prior individuals can NOT reproduce independently)
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53
Q

what are the METs discussed in lecture

A

Origin of first cells
Eukaryotic cells
Multicellularity
Multicellular individuality
Group living

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54
Q

how is cooperation a key component in eukaryotic cells

A

COOPERATION BETWEEN LARGE PROKARYOTIC CELL AND ENGULFED BACTERIA LIVING IN SYMBIOSIS TO EVOLVE INTO EUKARYOTIC ORGANELLES (endosymbiotic theory)

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55
Q

how is cooperation a key component in multicellularity

A
  1. Cooperation between cells minimizing conflict in order to gain an overall fitness benefit
  2. That whole group of cells has a cooperative nature to ultimately increase the fitness all around
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56
Q

how is cooperation a key component in multicellular individuality

A
  1. individuals are “integrated and indivisible wholes” that can reproduce and pass on heritable variation to their offspring
  2. Key advance: differentiation of cell lines into germ cells and somatic cells (they have different jobs)
  3. Natural selection likely favored this differentiation for efficiency (minimizing conflict)
  4. We have some cells which are reproductive cells (germ) and some cells which are not (somatic = control body structure and function). Both cells have different jobs and work together to make up who we are as people
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57
Q

how is cooperation a key component in group living

A
  1. GROUP: set of conspecific individuals of the same species living together who affect each other’s fitness (cooperation)
    • multicellular organisms living together
  2. Degree of living together within group varies, as does group size
  3. There are both benefits and drawbacks to group living.
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58
Q

who proposed the endosymbiotic theory and what was the hypothesis

A

Proposed by Lynn Margulis in 1970 to explain origin of chloroplast and mitochondria

  • Hypothesized that these organelles evolved due to long-term endosymbiotic mutualism between two prokaryotes (cooperation). The origin of eukaryotic cells was a symbiotic relationship between prokaryotic cells
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59
Q

what is the endosymbiotic theory

A

The origin of certain eukaryotic organelles (mitochondria and chloroplast) from prokaryotic cells that lived in symbiosis (together)

- Engulfed bacteria that made ATP evolved into mitochondria
- Engulfed bacteria that used sunlight as their own food evolved into chloroplast
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60
Q

what is modern day proof of endosymbiotic theory and what did it show

A

microcosm was observed for 3 years and contained 3 species:
- A green algae
- A bacterium (E. coli)
- A ciliated protozoan (typically eats E. coli)

They found that ciliated protozoan accidentally ingested algae and then were unable to digest them. Protozoans that ingested algae were at a survival advantage (it was passed along to daughter cells) when food (E.coli) was limited over protozoans that did not ingest algae

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61
Q

what evidence shows that mitochondria and chloroplast evolved from endosymbiosis

A
  1. Similar in size to prokaryotes
  2. Both have their own DNA that is shaped like bacterial DNA
  3. Able to reproduce separate to host cell
  4. Both have double membranes (evidence for phagocytosis)
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62
Q

what is the clonal (staying together) model of multicellularity

A

Staying together (clonal): single cell divides, but parent cells do NOT separate from daughter cells. Genotypes of all cells are clones (identical EX: HUMANS)
- Both complex and simple multicellular lineages (humans)

63
Q

what is an example of the clonal (staying together) model

A

“SNOWFLAKE” - PHENOTYPE YEAST

  1. Snowflake = multicellular groupings of yeast
  2. Genotype discovered that prevents mother-daughter cell separation (cells divide and just STAY TOGETHER)
  3. Multicellular groupings would outcompete the unicellular yeast and have higher levels of flocculation allow rapid sedimentation / escape from harsh conditions (fitness advantage)
64
Q

what is the non-clonal (coming together) / aggregative model of multicellularity

A

free living cells (which all have their own genetic material) joining together and forming a whole. Genotypes are potentially diverse (EX: SLIME)
- Typically simple multicellular lineages

65
Q

what is an example of the non-clonal (coming together) / aggregative model

A

SLIME MOLDS AGGREGATING (INCLUDING “SLUGS”)

  1. Slime molds are usually unicellular but under certain conditions, cells may aggregate
  2. Slime mold aggregates can form slugs that move more quickly than solitary cells (escape harsh environment conditions)
  3. Better protection from predators
66
Q

When is multicellularity considered true individuality?

A

When a group of cells become so interdependent and specialized that they can no longer survive or reproduce independently
- When there becomes a differentiation of cell lines into germ cells and somatic cells (multicellular individuality)

66
Q

what is an example that shows benefits and drawbacks of group living

A

EXAMPLE: EVOLUTIONARY TRADE OFFS CLIFF SWALLOWS
Cliff swallow nests are often clustered together on the sides of the cliff

  1. Negative: the number of swallow bugs per nest per week increases with colony size (more likely to carry parasites and can be detrimental to their immune system)

2.Positive: as colony size increases, the number of eggs that fail to hatch decreases

66
Q

what is the difference between multicellularity and multicellular individuality

A

Multicellularity we are looking at each cell being capable of reproduction while multicellular individuality is when there are some reproductive cells and some that are not

66
Q

what are the benefits of group living

A
  1. Group foraging / resource acquisition
  2. Predator defense
  3. Access to information
  4. Finding mates
66
Q

what are the drawbacks of group living

A
  1. Increased chance of disease
  2. Intraspecific competition
  3. Increased visibility to predators
67
Q

what is the difference between eukaryotic and prokaryotic cell

A

Eukaryotic
1. Animals, plants, fungi, protists
2. Membrane-bound nucleus and organelles present
- All eukaryotes have mitochondria but only some have chloroplasts (probably more likely recent addition to eukaryotic cells)
3. Much more sophisticated communication within cell, cytoplasmic elements, etc.
4. DNA found within linear chromosomes

Prokaryotic
1. Bacteria and archaea
2. NO nucleus or membrane-bound organelles
3. DNA in nuclear region (takes form of single circular chromosome)
4. Smaller, simpler

68
Q

what is the definition of aggregate

A

several cells that COME TOGETHER to form a whole component (non-clonal)

69
Q

what is the definition for germ/somatic cell

A

germ cells are involved with reproduction (sperm and egg cells). Somatic cells are responsible for body’s function and structure (non-reproductive cells: every other cells EXCEPT germ cells)

70
Q

what is cooperation

A

individuals working together for a common goal. Increases fitness in terms of biology.

71
Q

how long ago did prokaryotic and eukaryotic cells arise

A

prokaryotic = 3 bya
eukaryotic = ~1-2 bya

72
Q

what was hypothesized to be the first multicellular organisms

A

filamentous algae (1 bya)
sponges (600 mya)

73
Q

what is multicellularity

A

when a group of cells form a whole
- this transition has evolved independently in many lineages many times

74
Q

could predation have caused the evolution of multicellularity (what research was discussed in lecture)

A

introducing microscopic predators to 5 pops of single celled algae. after 50 weeks and 750 generations. simple multicellular structures had evolved in 2/5 pops. this gave them better protection from predators because they were too big to be eaten.

75
Q

Major evolutionary transitions include all except
A. Group living
B. Movement from water to land
C. Eukaryotic cells
D. Multicellular individuality
E. First cells
F. Multicellularity

A

B. Movement from water to land

76
Q

Every major evolutionary transition involves ______? (FILL IN THE BLANK)

A

cooperation

77
Q

Endosymbiotic theory explains
A. The origin of multicellularity
B. The origin of organic biomolecules
C. The origin of certain eukaryotic organelles
D. The origin of mutualism

A

C. The origin of certain eukaryotic organelles

78
Q

All of the following are evidence for endosymbiotic theory except

A. mitochondria/chloroplast have their own DNA that is separate from nuclear DNA

B. mitochondria/chloroplast replicate separately from the cell

C. mitochondria/chloroplasts are about the same size of a prokaryotic cell

D. mitochondria/chloroplasts have linear chromosomes

A

D. mitochondria/chloroplasts have linear chromosomes

79
Q

In the “microcosm” described in the last couple of slides, which of the following was observed?

A. The ciliated protozoans were able to digest algal cells to use as a food source

B. E. coli was able to use algal cells as a food source

C. The ciliated protozoans who harbored algal cells were at a survival advantage when E. coli was scarce

D. The ciliated protozoans who harbored E. coli cells were at a survival advantage

E. Algal cells and E. coli are competed for food

A

C. The ciliated protozoans who harbored algal cells were at a survival advantage when E. coli was scarce

80
Q

Match the example to the model of multicellularity displayed. (CLONAL, NONCLONAL)
Snowflake yeast phenotype = ?
Slime mold aggregates (including “slugs”) = ?

A

Snowflake yeast phenotype = CLONAL
Slime mold aggregates (including “slugs”) = NON-CLONAL

81
Q

Which of the following statements about multicellularity is true? (SELECT ALL THAT APPLY)

A. Multicellularity may have evolved in some lineages as a way to avoid predation

B. Multicellularity has evolved many times in eukaryotes

C. Major eukaryotic groups either contain only multicellular or only unicellular species

D. Eukaryotes became multicellular upon endosymbiosis with bacteria

A

A. Multicellularity may have evolved in some lineages as a way to avoid predation

B. Multicellularity has evolved many times in eukaryotes

82
Q

Describe conditions that could have favored the evolution of Eukaryotic cells.

A
  1. Symbiosis: The endosymbiotic theory suggests that eukaryotic cells evolved through a symbiotic relationship between different species of prokaryotes. For example, mitochondria and chloroplasts are believed to have originated from free-living bacteria that entered into a symbiotic relationship with a host cell.
  2. Increased Genetic Material: The presence of more genetic material allowed for greater complexity and specialization. Eukaryotic cells have multiple chromosomes, which facilitated the evolution of more complex regulatory mechanisms.
  3. Compartmentalization: The development of internal membranes and organelles allowed for compartmentalization of cellular processes, increasing efficiency and allowing for more complex cellular functions.
83
Q

Describe conditions that could have favored the evolution of Multicellularity.

A
  1. Ecological Benefits: Forming multicellular groups provided advantages such as better protection from predators, more efficient feeding, and improved environmental resilience.
  2. Cell Adhesion and Communication: The evolution of mechanisms for cells to adhere to each other and communicate was crucial. This allowed cells to coordinate their activities and function as a cohesive unit.
  3. Division of Labor: Specialization of cells for different functions (e.g., somatic vs. reproductive cells) increased the efficiency and survival of multicellular organisms.
84
Q

Describe conditions that could have favored the evolution of Multicellular Individuality.

A
  1. Genetic Relatedness: High genetic relatedness among cells within an organism reduced conflict and promoted cooperation. This was often achieved through development from a single fertilized egg.
  2. Mutual Dependence: Cells became specialized to the extent that they could not survive independently, leading to mutual dependence and the formation of a new level of individuality.
  3. Conflict Suppression: Mechanisms evolved to suppress internal conflict, such as programmed cell death and immune responses to rogue cells, ensuring the integrity of the multicellular organism.
85
Q

Describe conditions that could have favored the evolution of Group Living.

A
  1. Kin Selection: High relatedness within groups favored the evolution of cooperative behaviors, as individuals could increase their inclusive fitness by helping relatives.
  2. Ecological Pressures: Environmental pressures such as predation and resource scarcity favored the formation of groups for better defense and more efficient resource utilization.
  3. Communication and Coordination: The evolution of communication systems allowed individuals to coordinate their activities, increasing the efficiency and survival of the group.
  4. Division of Labor: Similar to multicellularity, group living often involved a division of labor, with different individuals specializing in different roles (e.g., foraging, defense, reproduction).
86
Q

what is reproductive isolation

A

the mechanisms that prevents different species from interbreeding and producing fertile offspring. (This can occur due to physical, behavioral, temporal, or ecological barriers)

87
Q

what is pollination

A

Pollination is the process by which pollen from the male part of a flower (the anther) is transferred to the female part (the stigma), allowing fertilization to occur and seeds to develop.

88
Q

what organisms can serve as pollinators

A
  1. Bees
  2. butterflies and moths
  3. birds
  4. beetles
  5. flies
  6. wind and water
89
Q

what is important to know about columbines

A

All columbine flowers have spurs and other structural similarities. The spurs contain nectar, a sugar-rich reward for pollinators who visit flowers.

90
Q

what is the main research question for the columbine reading

A

how the length of columbine nectar spurs has evolved in relation to their pollinators’ tongue lengths and whether this evolution follows Darwin’s coevolutionary race hypothesis or the pollinator shift hypothesis.

91
Q

what is the coevolutionary arms race hypothesis (Darwin / Wallace)

A
  1. Nectar spurs and pollinator tongues are engaged in a one-to-one coevolutionary “race”
  2. There is a gradual, mutual evolutionary increase in both the nectar spur length of the plant and the tongue length of the pollinator.
  3. Suggested that plants with the longest nectar spurs have a selective advantage because their reproductive organs optimally contact pollinators and thus they achieve the greatest reproduction, whereas pollinators with the longest tongues have a selective advantage because they obtain the largest food reward.
  4. Spur length and pollinator tongue length then coevolve by following gradually shifting adaptive peaks
92
Q

what is the pollinator shift hypothesis from the reading

A
  1. Suggests that tongue lengths are relatively fixed and spurs evolve in a one-sided process to fit them
  2. The tongue length of a pollinator may have evolved before an association with a plant species owing to selection on body size or in response to the spur lengths of other plant species (rapid evolution)
  3. spur length increases significantly when plants adapt to new pollinators with pre-existing longer tongues.
93
Q

what were the studies findings

A
  1. columbines show a significant evolutionary trend for INCREASING SPUR LENGTH during DIRECTIONAL shifts to pollinators with LONGER tongues.
  2. evidence for ‘punctuated’ change suggesting that columbines nectar spurs RAPIDLY EVOLVE to fit adaptive peaks predefined by pollinator morphology. (pollinator shift hypothesis)
  3. nectar spurs will become LONGER thru time as spurs evolve to match a series of relative stable peaks defined by tongue lengths
94
Q

what hypothesis does the columbine study support

A

the comparative phylogenetic evidence indicates that the majority of spur-length evolution in columbines fits the pollinator shift model.

95
Q

What is meant by the statement “there has been significant directionality in pollinator shifts and a lack of reversals in columbines”

A

suggests that in the evolutionary history of columbine flowers (genus Aquilegia), there has been a consistent trend toward certain types of pollinators (like bees or hummingbirds) over time.

96
Q

Place the following pollinator categories in order from shortest to longest tongue. (Shortest tongue = 1 and longest tongue = 3)

Humming birds, hawkmoth, and bumble bee (place in order)

A
  1. Shortest tongue/spur = bumble bee
  2. Middle = hummingbird
  3. Longest tongue/spur = hawkmoth
97
Q

What is the function of the nectar spur structures on columbine flowers?

A. they contain a nectar reward to attract pollinators

B. they produce seeds

C. they allow the flower to survive better in drought conditions

D. they deter herbivores

E. they produce pollen

A

A. they contain a nectar reward to attract pollinators

98
Q

Reproductive isolation among columbines, and subsequent speciation events, has occurred because

A. differences in nectar spur length correspond with different pollinators, minimizing gene flow across plant species that rely on different pollinator groups.

B. fragmentation of the landscape has resulted in geographical isolation of populations and subsequent allopatric speciation events.

C. differences in floral coloration result in different pollinators being attracted, minimizing gene flow across plant species that attract different pollinator groups.

D. climate change has resulted in phenological differences between flowering times of populations of columbines, minimizing gene flow across species through temporal reproductive isolation.

A

A. differences in nectar spur length correspond with different pollinators, minimizing gene flow across plant species that rely on different pollinator groups.

99
Q

Which of the following were findings of the study? Check all that apply.

A. Speciation in columbines has most likely occurred via the coevolutionary arms race model.

B. Columbines in the Aquilegia lineage were most often pollinated by bumble bees.

C. Once an Aquilegia species has adapted to one pollinator type, the spur length remains relatively stable until introduction of another pollinator type.

D. Speciation in columbines has most likely occurred via the pollinator shift model.

E. Changes in nectar spur length in the Aquilegia lineage were most often directional shifts toward increased spur length.

F. Changes in nectar spur length in the Aquilegia lineage were most often directional shifts toward decreased spur length.

G. There were at least seven different shifts between unrelated pollinators in the Aquilegia lineage.

A

C. Once an Aquilegia species has adapted to one pollinator type, the spur length remains relatively stable until introduction of another pollinator type.

D. Speciation in columbines has most likely occurred via the pollinator shift model.

E. Changes in nectar spur length in the Aquilegia lineage were most often directional shifts toward increased spur length.

G. There were at least seven different shifts between unrelated pollinators in the Aquilegia lineage.

100
Q

Why are long nectar spurs advantageous to columbines?

A. The nectar reward is difficult to reach and so the pollinator will be more likely to transfer pollen as it interacts with the flower.

B. They are more attractive to pollinators than short spurs.

C. They cannot be reached by nectar-robbing bees and so save the nectar reward for true pollinators.

D. They produce the largest seeds, resulting in offspring that are more likely to survive.

A

A. The nectar reward is difficult to reach and so the pollinator will be more likely to transfer pollen as it interacts with the flower

101
Q

Whittall and Hodges investigated two hypotheses for the evolution of long nectar spurs in columbines. Match the hypothesis to its description.

HYPOTHESIS
Coevolutionary arms race
Pollinator Shift

DESCRIPTIONS
when a new, longer-tongued pollinator becomes the main visitor to a columbine, rapid evolution of longer nectar spurs occurs to improve pollination chances

pollinators with the longest tongues obtain the greatest nectar rewards, while plants with the longest spurs are selected for because they are pollinated most efficiently

A

Coevolutionary arms race = pollinators with the longest tongues obtain the greatest nectar rewards, while plants with the longest spurs are selected for because they are pollinated most efficiently

Pollinator Shift: when a new, longer-tongued pollinator becomes the main visitor to a columbine, rapid evolution of longer nectar spurs occurs to improve pollination chances

102
Q

The authors said that pollination syndromes in columbines are not all monophyletic. How do they explain this?

A

They used a Shimodaira-Hasegwa test; P < 0.00001), indicating that multiple INDEPENDENT shifts have occurred between UNRELATED POLLINATORS: 2 transitions from bumble-bee to hummingbird pollination and 5 shifts from hummingbird to hawkmoth pollination

103
Q

How do we define a species?

A

We don’t know. It is difficult to define a species because there are many ways to define it
- There are many species “concepts” including evolutionary, phenetic, phylogenetic, ecological, and biological

  • Focusing on biological for this lecture
104
Q

what is the Biological species concept (BSC)

A
  1. Introduced by Ernst Mayr 1942
  2. Define species as: group of populations that may potentially interbreed and are reproductively isolated from other such groups
  3. Gene flow can occur between populations of same species, but NOT between populations of DIFFERENT species
105
Q

what are problems with the BSC definition

A

Can NOT apply to asexual organisms such as bacteria where there’s no such thing as reproductive isolation because they reproduce asexually OR hybrids

106
Q

what reproductive isolating mechanisms

A

Under BSC, species are separated by barrier traits that prevent gene flow (we can see multiple at a time)
(can be pre/postzygotic)

107
Q

what is prezygotic mechanism?

A

Prevent / deter individuals from different populations from mating with one another, or prevent fertilization if mating occurs (sometimes prevent mating act all together) (prevents actual fertilization of the egg (prior to the zygote forming)

108
Q

what are the different types of prezygotic mechanisms

A
  1. Habitat: different location (individuals are never going to encounter one another)
  2. Temporal: breed at different times
  3. Behavioral: different mating rituals, courtship, etc. (animals)
  4. Mechanical: physical barrier (parts don’t fit, physically sperm and egg can NOT meet up)
  5. Gametic: aquatic animals (release sperm and egg into water; gametes may come into contact with one another but fertilization does not occur) (EX: sponge and jellyfish)
109
Q

what is an example of prezygotic mechanism

A

Male bowerbirds build bower structures that serve as a place where the male will be able to dance and sing from the bower to attract mates of the same species ONLY. They use different colors, materials, and shapes for their bowers.
- Courtship = behavior mechanism isolation

110
Q

what is postzygotic mechanism

A

Operate after fertilization and conception (occur after fertilization of the egg)

- Reduced hybrid viability: embryo does NOT survive

- Reduced hybrid fertility: hybrid NOT fertile, or fitness greatly reduced

- Hybrid Breakdown: hybrids can reproduce but offspring of hybrid unsuccessful
111
Q

what are examples of postzygotic

A
  1. zonkey
  2. liger
  3. mule
112
Q

What evolutionary forces drive speciation

A
  1. Mutation = provides RANDOM, raw material in order for evolution to occur (new alleles introduced by random changes in an organism’s DNA sequence)
  2. Natural Selection = mechanism of evolution. Over time, beneficial traits become more common in a population due to increased survival and reproduction of individuals that have those traits.
  3. Genetic Drift = in finite populations, allele frequencies randomly change over time due to random chance (sampling error). STRONGEST IN SMALL POPULATIONS
113
Q

what is allopatric speciation

A
  1. Reproductive isolating mechanisms evolve between populations when they are GEOGRAPHICALLY isolated from each other (MOST COMMON)
  2. Genetic drift and natural selection cause separated populations to diverge from one another and ultimately lead to speciation
114
Q

what is the vicariance model of allopatric speciation

A

development of geographical barrier splits population in two

115
Q

what is the peripheral isolate (dispersal) model of allopatric speciation

A

migration of part of population across pre-existing geographical barrier to new area; population that migrated may experience strong founder effects (nonrandom sampling of the genetic pool of parent pop. in the new pop)

116
Q

what is an example of allopatric speciation

A

Alpheus Shrimp (vicariance model)

  1. 10 million years ago: big population of shrimp freely able to move back and forth between North America and South America and interbreed with each other
  2. 5 million years ago: emergence of land bridge (geographical barrier) ultimately separating shrimp population and disallowing movement between the shrimp pops.
  3. Present day: shrimp populations are completely isolated and are considered to have allopatric speciation event occur
117
Q

what is sympatric speciation

A
  1. NO GEOGRAPHIC BOUNDARY SEPARATES POPULATIONS; tricky to determine what introduces reproductive isolation
  2. Disruptive selection (two or more extreme phenotypes favored) might be causing multiple traits to be favored and assortative mating (individuals choose mates that are similar to themselves)
  3. Genetic event (chromosome rearrangement, changes in ploidy)
118
Q

what is the first example discussed for sympatric

A

APPLE MAGGOT FLIES

  1. These flies would ALWAYS lay their eggs on the fruit of the Hawthorn trees and the eggs would hatch within the fruit. Over time, apple trees were introduced into the area of some hatchery with Hawthorn trees. It was observed that maybe by accident or potentially by chance (who knows) some of the individuals started to utilize the niche of the apple trees
  2. Some flies continued to live and breed and return to Hawthorn tress and others moved onto apple trees and ended up diverging
119
Q

what is the second example of sympatric speciation

A

POLYPLOID PLANTS

  1. Polyploid plants are resilient when it comes to chromosomal duplications and changes in ploidy
    • EX: strawberries and bananas
  2. Polyploid pants had bunches of copies of chromosomes within cells and it provided proof of genetic rearrangement and duplication could lead to speciation
120
Q

what is parapatric speciation? what is a cline and hybrid zone?

A

NO GEOGRAPHIC BARRIER, but instead a GRADIENT of selective conditions across an area resulting in genotypic/phenotypic cline

Cline: spatial gradient in frequency of genotypes/phenotypes along which populations experience different selective pressures

Hybrid zone: somewhere along cline; here gene flow occurs; complete speciation will occur if gene flow stops along hybrid zone

121
Q

what is the first example of parapatric speciation

A

SWEET VERNAL GRASS NEAR TRELOGAN MINE

  1. Soil highly contaminated with heavy metals, but as you move further from the mine (pasture) the contamination gets less and less
  2. Divergence in zinc tolerance
  3. Flowering time difference (prezygotic mechanism = temporal)
  4. Mine grass self-fertilizes more than pasture grass
122
Q

what is the second example of parapatric speciation

A

AMERICAN ORIOLES

  1. Bullock’s Oriole and Baltimore Oriole are morphologically very similar, but sing different songs to attract mates
  2. Male Bullock’s will NOT attract Baltimore or vice versa because song is different
  3. In the hybrid zone, both orioles can be found and potential gene flow, but since songs are diverged across geographic area you don’t see intermixing of the two orioles
123
Q

what are the similarities of the speciation events

A
  1. Each speciation event results in the reproductive isolation of individuals
  2. Parapatric speciation and sympatric speciation both describe how populations diverge into separate species without a geographic barrier to dispersal
124
Q

what are differences in the speciation events

A
  1. Allopatric is the only event that has a geographical barrier
  2. In parapatric speciation, the populations are adjacent to one another and typically have a hybrid zone between the populations
  3. Sympatric has NO geographical barrier and NO hybrid zone
125
Q

Why does natural selection strongly favor traits that prevent hybridization?

A
  1. Selection favors traits that facilitate genes being passed down
  2. Hybrids are often sterile / less fit
  3. Production of sterile offspring is costly to individual
    • Genetic dead-end
    • Waste of parental effort/gametes (evolutionary standpoint)
126
Q

what is favored by selection

A

ALLELES THAT REDUCE MATING WITH OTHER SPECIES

127
Q

what is speciation

A

process by which new species are formed (extreme effect of evolution)
- Evolution of reproductive isolating mechanisms

128
Q

what is the 2 main focus points for speciation

A
  1. New species form as evolutionary forces cause populations to become reproductively isolated from each other
  2. Gene flow is LIMITED/ELIMINATED for long enough that new species are formed
129
Q

what is adaptive radiation

A

multiple speciation events over time from a single ancestral (founder) species. Consequence of exploitation of new niches

130
Q

what is the first example of adaptive radiation

A

Galapagos finches

  1. Finches most likely arose from a single ancestral mainland species that over time diverged into new species or a variety of new species as individuals went and exploited new niches and also dispersed in diff. Islands of galapagos
131
Q

what is the second example for adaptive radiation

A

Cichlids (sympatric speciation) very diverse and evolve quickly

  1. 3,000 species - 10% of teleost fish diversity
  2. Distributed through Central, South America, Africa, Madagascar, India
  3. Masters of niche partitioning, resulting in adaptive radiation
    • 500 species or more in large African lakes
132
Q

what is hybridization

A

the process where individuals from two distinct populations or species interbreed, producing offspring with mixed genetic ancestry

133
Q

what is secondary contact

A

barrier to gene flow between allopatric populations is removed; selection against hybridization and ultimately complete speciation process)

  1. If reproductive isolation is significant enough to place hybrids at disadvantage, selection will be strong AGAINST hybridization
  2. Speciation will proceed to completion
134
Q

what is secondary reinforcement

A

populations come back together and hybrids are at a disadvantage, there’s selection for any traits which prevent hybridization

135
Q

what is reproductive character displacement

A

reproductive trait is LESS SIMILAR in zones of SYMPATRY than in areas of allopatry (in hybrid zones, reproductive characteristics are less similar than in other areas)

136
Q

what is an example of reproductive character displacement

A

Satsuma largillierti and Satsuma eucosmia (SNAILS)

  1. Largely allopatric but small zone of sympatry exists (likely due to secondary contact)
  2. Measured morphological characteristics of genitalia
  3. Significantly greater divergence of penis length and vaginal depth in sympatry (much less compatible) than allopatry
137
Q

what is the pollinator shift hypothesis

A

when a new, longer-tongued pollinator becomes the main visitor to a columbine, rapid evolution of longer nectar spurs occurs to improve pollination chances

138
Q

The biological species concept defines species as

A. Sharing a common ancestor that is different from other species

B. Occupying a different niche from other species

C. Morphologically different from other species

D. Being reproductively isolated from other species

A

D. Being reproductively isolated from other species

139
Q

A mule is the offspring of a female horse and a male donkey. The mule is a sterile animal that cannot produce its own offspring. This is an example of a

A. Prezygotic isolating mechanism

B. Postzygotic isolating mechanism

A

B. Postzygotic isolating mechanism

140
Q

Genetic drift is when

A. Individuals prefer to mate with individuals that have different genotype and/or phenotype from their own

B. New alleles are introduced into a population as individuals from a different population move in

C. Allele frequencies fluctuate due to random chance in finite populations

D. A population experiences reduced fitness due to buildup of deleterious recessive alleles

E. Heterozygote fitness is lower than the fitness of either homozygote fitness

A

C. Allele frequencies fluctuate due to random chance in finite populations

141
Q

The speciation events that resulted in new species of shrimp on either side of the Panama isthmus can best be explained as

A. An allopatric speciation event via vicariance

B. An allopatric speciation event via peripheral isolation (dispersal)

A

A. An allopatric speciation event via vicariance

142
Q

How are sympatric and allopatric speciation different from each other?

A. Sympatric speciation involves reproductive isolation while allopatric speciation does not

B. Allopatric speciation occurs after a geographic barrier occurs between populations, while sympatric speciation events involve no geographic barrier

C. Allopatric speciation occur when gene flow is limited between populations, while gene flow still occurs in sympatric speciation

D. Both B and C

E. All of the above

A

B. Allopatric speciation occurs after a geographic barrier occurs between populations, while sympatric speciation events involve no geographic barrier

143
Q

The host tree specificity of Rhagoletis pomonella reduces gene flow between the apple and hawthorn fly races by 4% to 6% in each generation because individuals tend to mate with flies that have the same fruit preference. This is an example of

A. Secondary contact
B. Assortative mating
C. Resource competing
D. Allopatric speciation

A

B. Assortative mating

144
Q

Match the following words to the correct definitions in the table below. (cline and hybrid zone)

A. spatial gradient in frequency of genotypes/phenotypes along which populations experience different selective pressures

B. gene flow occurs between populations in this area

A

A = cline
B = hybrid zone

145
Q

Parapatric speciation and sympatric speciation both describe how populations diverge into separate species without a geographic barrier to dispersal. What distinguishes these two modes of speciation?

A. In parapatric speciation, the populations are adjacent to one another and typically have a hybrid zone between the populations

B. In parapatric speciation, the populations once had a barrier between them, but the barrier has been removed

C. In sympatric speciation, genetic drift is the driving force of speciation

D. In sympatric speciation, the populations are adjacent to one another and typically have hybrid zone between the populations

A

A. In parapatric speciation, the populations are adjacent to one another and typically have a hybrid zone between the populations

146
Q

True or False? Adaptive radiation only involves allopatric speciation events.

A

FALSE

147
Q

When previously allopatric populations come into secondary contact, completion of the speciation process often occurs. What is the main reason for this?

A. Hybrids have a selective advantage and become a new species

B. Hybrids are at a selective disadvantage compared to offspring of within-population matings and so hybridization is selected against

C. Geographic barriers appear, disallowing hybridization

D. Hybrids display assortative mating and will not mate with the parent populations

E. Hybrids populate new niches and become isolated from parent populations

A

B. Hybrids are at a selective disadvantage compared to offspring of within-population matings and so hybridization is selected against

148
Q

how are pollinator syndromes similar and different.

A

Similar: they all involve adaptations that enhance the likelihood of successful pollination by attracting specific pollinators.

Differ: differ in the specific traits that have evolved to attract different types of pollinators.

149
Q

How can pollinators cause reproductive isolation in flowering plants?

A

Pollinators can cause reproductive isolation by favoring certain floral traits that are adapted to their specific morphology and behavior. This can lead to the evolution of distinct pollination syndromes that prevent cross-pollination between plants with different syndromes.

EVOLUTION (5 decks)

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