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Evolution > Natural Selection I and II > Flashcards

Natural Selection I and II Flashcards

1
Q

what is evolution by natural selection

A
  • Darwin’s proposed mechanism explaining how species change
  • a process which is the logical outcome of 4 postulates
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2
Q

what are Darwin’s 4 postulates

A
  1. variability in traits
  2. heritability in traits
  3. variability in fitness
  4. fitness differences are associated with traits
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3
Q

Darwin’s 4 postulates - variability in traits

A
  • individuals within a population are variable for some trait
  • refers to V in VIST
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4
Q

Darwin’s 4 postulates - heritability in traits

A
  • trait variability among individuals are, at least in part, passed from parents to offspring
  • refers to I in VIST
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5
Q

Darwin’s 4 postulates - variability in fitness

A
  • some individuals are more successful at surviving and reproducing than others
  • refers to S in VIST
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6
Q

Darwin’s 4 postulates - fitness differences are associated with traits

A
  • survival and reproduction of individuals are not random; instead they correlated to variability in traits
  • refers to S in VIST
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7
Q

what is Darwinian fitness

A
  • an individual’s ability to survive and reproduce
  • in reality, it is the number of copies of genes passed on
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8
Q

Peter and Rosemary Grant experiment

A

tested if variation and seed availability caused evolution by natural selection in a population of Darwin finches

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9
Q

Grants experiment - what are Darwin’s finches

A
  • a group of very closely related species of birds endemic to the Galapagos Islands
  • all descendant of a flock that colonized the islands from the Caribbean
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10
Q

Grants experiment - is P1 true

A
  • observed species and plotted them
  • saw a great variability in beak depth
  • yes, P1 is true
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11
Q

Grants experiment - how did they check for P2

A
  • they estimated the heritability of beak depth
  • plotted it using a parent-offspring regression
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12
Q

Grants experiment : P2 - what is the reasoning behind the parent-offspring regression

A
  • if differences among individuals are due to differences in the alleles they inherited, then offspring will resemble their parents
  • heritability may be estimated by comparing parent and offspring traits
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13
Q

Grants experiment : P2 parent-offspring regression - what is heritability

A
  • the proportion of the variation observed in a population that is due to variation in genes
  • it can take any value between 0 and 1
  • slope on graph = heritability
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14
Q

Grants experiment - is P2 true

A
  • yes- Grants found about 65% of variation in beak depth is due to differences in genes
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15
Q

Grants experiment - is P3 true

A
  • yes
  • 84% of the finches disappeared corresponding to the decline in the availability of the seeds (due to a drought)
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16
Q

Grants experiment - is P4 true

A
  • yes
  • Grants compared pre-drought and post-drought beaks and saw differences corresponding to the change in seeds
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17
Q

Grants experiment - did the population evolve

A

yes bc all P’s are met

18
Q

what can natural selection explain

A

the observation that organisms are well-suited to their environments and lifestyles (fit between form and function)

19
Q

define adaptation

A
  • a trait that increases the ability of an individual to survive or reproduce compared with individuals without the trait in a certain environment
20
Q

define Darwinian hypothesis

A

a hypothesis about a noteworthy or unusual trait possessed by an organism

21
Q

what does a Darwinian hypothesis contain?

A
  • hypothesizes that the trait is an adaptation
  • explain how the trait evolved from an ancestral condition
  • specifically considers the 4 P’s for evolution by natural selection
22
Q

domestication - what traits may be selected for

A
  • Size – fast growing
  • Less aggression
  • Friendly: no antipredator behavior
23
Q

domestication example - Colorado

A

gave rainbow trout in hatcheries predation cues (alarm and predator cues) to see if they had antipredation behavior

24
Q

domestication example: Colorado - what was the result

A

the highly domesticated hatchery-reared fish retain the innate ability to express appropriate responses to the threat of predation

25
Q

domestication example: Colorado - will this work on the real world

A
  • yes
  • there is no difference in results in domesticated vs non-domesticated fish
26
Q

common misconception in evolution - what does selection act on

A

individuals

27
Q

common misconception in evolution - what changes as a result of selection

A
  • genes
  • phenotypes
  • populations
28
Q

common misconception in evolution - how do we measure evolution

A
  • over time
  • measuring genes or allele frequency
  • in populations
29
Q

common misconception in evolution - will selection always cause evolution

A
  • not always
  • will not happen if the trait is not heritable
30
Q

common misconception in evolution - can selection occur within a generation

A

yes

31
Q

common misconception in evolution - can evolution occur within a generation

A

no

32
Q

common misconception in evolution - does selection act for the good of the species

A
  • no
  • bc selection acts on individuals
33
Q

common misconception in evolution - is evolution forward thinking (preparing)

A
  • no
  • exaptation and secondary adaptations
34
Q

common misconception in evolution: is evolution forward thinking (preparing) - define exaptation

A
  • a novel function of an existing trait
  • represents happenstance
  • an exaptation enhances an individuals fitness, not bc natural selection is conscious or foresighted
35
Q

common misconception in evolution: is evolution forward thinking (preparing) - define secondary adaptations

A

additional adaptations added to exaptations

36
Q

common misconception in evolution - can selection generate variation

A
  • no
  • only acts on existing variation
37
Q

common misconception in evolution - does natural selection lead to perfection

A
  • no
  • bc there are constraints within organisms (ex: trade offs)
38
Q

common misconception in evolution - is natural selection random

A

no

39
Q

common misconception in evolution - does selection act to make things more advanced

A

no

40
Q

common misconception in evolution - no one has seen a species formed in the wild

A
  • false
  • Grants experiment: they found a new species of Darwin finch
41
Q

explain evolution regarding reproducing

A

individuals with traits that are conductive to surviving and reproducing make a bigger genetic contribution to the next generation than individuals with traits that are conducive to dying and not reproducing in a given environment

Evolution (18 decks)

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