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Evolution > Exam 4 > Flashcards

Exam 4 Flashcards

1
Q

How did earth gain its atmosphere?

A

From outgassing ( when the earth was cooling down from collision and volcanoes released gas.

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2
Q

Formation of building blocks

A

Addition of energy to the reducing atmosphere allows prebiotic molecules to be formed.

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3
Q

Self splicing introns

A

Acting as a ribozyme to splice itself out and make mature RNA transcript.

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4
Q

Stromatolites

A

community of bacteria lives on the surface and creates layers of calcium carbonate where cells can sometimes be trapped and found.

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5
Q

Subduction

A

when a marine plate pushes against a continental plate and creates a subduction zone.

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6
Q

Nested sets

A

organisms that fall into hierarchical categories

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7
Q

Classification criteria

A
  1. Objectivity criterion: use characteristics that come from the organisms themselves.
  2. Naturalness: the way we grouped them together would be considered natural if whatever subset of characters we use to put things into groups, we would find the same group if we picked another subset of characteristics.
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8
Q

Character conflict

A

different sets of characters indicate different groups

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9
Q

Value of objective and natural classification

A

will allow rational persons to independently discover the same classification scheme

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10
Q

Sister species

A

species derived from the same most recent common ancestor (MRCA)

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11
Q

homology

A

Character shared between species because of common descent.

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12
Q

Analogy (homoplasy)

A

Characters shared due to convergence (does not help us figure out relationships)

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13
Q

Similarity

A

two characters appear like each other without making any claim about common descent or convergence

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14
Q

Plesiomorphy (Ancestral homology)

A

evolve before some change in that homology

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15
Q

Symplesiomorphy (shared ancestral homology)

A

Inherited from a most recent common ancestor of a group but not all the descendants from the common ancestor of the group have the character (will give us a natural classification scheme) -> cannot bc they dont include all members of the clade defined by the first common ancestor with the trait.

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16
Q

Apomorphy (derived homology )

A

thing that comes after the new version of the trait

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17
Q

Autapomorphy

A

derived in a single lineage

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18
Q

Synapomorphy (shared derived homologies)

A

Can be used to determine ALL the members of a clade without ambiguity

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19
Q

Monophyletic group

A

ALL the descendants from a single common ancestor (created using synapomorphies)

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20
Q

Paraphyletic group

A

SOME but not all the descendants of a most recent common ancestor (created using symplesiomorphies)

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21
Q

Polyphylectic group

A

species not grouped due to the same common ancestor (produced using analogies)

22
Q

Analogies

A

can NEVER be used to make inferences about relationships

23
Q

Cladistic

A

groups are related to one another by their most recent common ancestor

24
Q

Star tree

A

when you dont know the relationships of the species (all lines coming from the same root)

25
Q

Partially resolved

A

Shows more than two branches on the tree

26
Q

Order of the tips on the tree

A

The order at the tips of the tree do not mean anything in how closely related the species are

27
Q

Parsimony

A

tree that has the least number of changes (steps) for characters

28
Q

Parsimony Justification

A

If particular characters dont change too often on a tree then you can use parsimony to make good inferences on what really happened (fast rate of speciation will not be good with parsimony)

29
Q

Two steps to producing a tree

A
  1. Find the shortest possible unrooted tree, that is, the one requiring the fewest evolutionary changes (unroot the tree)
  2. Root the tree (after finding the best unrooted tree)
30
Q

Morphological characters

A

Observed character states -> find true homologies -> figure out character polarities (determining synapomorphies) -> parsimony for ambiguities -> root tree

31
Q

Molecular characters

A

Observed character state -> parsimony -> unrooted tree -> determine character polarities -> root tree

32
Q

3 principals to determine homologies

A
  1. Homologous characters show the same fundamental structure
  2. Homologies have the same fundamental relationships to surrounding characters
  3. Same embryonic development in different groups

cant use these methods to distinguish homologies and analogies in DNA sequence

33
Q

Pitfalls in determining homologies

A

-Mistakenly classify analogies as homologies
-Mistakenly classify homologies as analogies

34
Q

Character polarity

A

trying to figure out which wat a character formed
ex: A -> A’ or A <- A’

35
Q

Determine ancestral and derived states

A
  1. Outgroup comparison: Use a close relative of species being studied to determine the ancestral character state (can use sister species group)
  2. The embryological criterion: evolutionary sequence gets more and more specific as these new developmental features get added toward the end of a sequence. (evolutionary history of the trait)
  3. Paleontological criterion (fossil record): any characters recorded in the fossil record (mostly of hard parts)
36
Q

Characters for molecular method

A

Nucleotides and amino acids

37
Q

Positional homology

A

When you align sequences, you’re tracing the history of that position in the sequence

38
Q

Issues with phylogenetic inference

A
  1. the number of combinations is enormous even with a relatively small number of taxa
  2. minimally need almost as many synapomorphies as taxa to be resolved, preferably more
  3. need to pick a molecule that evolves at an appropriate rate
39
Q

Coevolution

A

When two or more species act as reciprocal selective agents/forces on one another

40
Q

Feedback in the system for coevolution

A

Their selection for each other can change the way they select traits in the future

41
Q

Coevolution species interactions

A

Consumer-resource: predation, herbivory, parasitism
Mutualism

42
Q

Coadaptation

A

mutual adaptation of two species to one another

Positive (mutualism): a relationship where two or more species experience increased fitness from mutual adaptations
Negative (antagonistic or arms race): a relationship where one species experiences increased fitness, but the other experiences decreased fitness

43
Q

Cospeciation

A

when a pair of species that are associated with one another speciate in parallel

44
Q

Fahrenholz’s rule

A

coevolving parasites and hosts should speciate approximately simultaneously (not only topologies are the same but so is the timing)

45
Q

Negative coevolution (the nature of the cycle)

A
  1. Feeding of insects on plants exerts a selective pressure on the plants for antiherbivore defenses (to reduce consumption)
  2. Defense creates selective pressure on the insects for resistance (resistance to the plant’s defense)
  3. Next round of evolution: plants evolve a modified or new set of chemicals

continuous cycle

46
Q

Virulence

A

the degree to which a parasite/disease reduces the host’s fitness

47
Q

group selection

A

long term benefit of the group as a whole is favored over what an individual does

48
Q

Virulence mode of transmission

A

vertical transmission: from parent to offspring (promotes lower virulence)
horizontal transmission: movement from one host to another without respect to the genetic relationship of the hosts

49
Q

Rate of infection

A

How often does an individual get infected

  • if something is getting infected a lot it’ll probably have multiple genotypes inside of its body at any one time
50
Q

High rate of infection

A

Rate of infection is so high individuals are getting infected with both genotypes
-virulent type will dominate over avirulent

51
Q

Low rate of infection

A

Individuals only get infected once

52
Q

Hominins

A

all the different fossil lineages that are part of that overall human lineage

Evolution (2 decks)

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