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Biology 101 > Evolution (PP16) > Flashcards

Evolution (PP16) Flashcards

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1
Q

What is evolution and what does it involve>

A

Evolution is the heritable change in characteristics within populations over the span of multiple generations

It involves the non-random selection of random variation resulting in the development & diversification of life

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2
Q

Does evolution increase or decrease with time?

A

This diversity tends to increase with time

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3
Q

What is variation caused by?

A

Mutation

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4
Q

How does a mutation arise??

A

Note: mutations are constantly arising due to small errors in the replication process – each generation is slightly different from the previous

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5
Q

do mutations have affect on phenotype?

A

Mutations are random, and may have small, large, or no effect on phenotype

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6
Q

who do you associate with catastrophism

A

george cuvier

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7
Q

Who is georges cuvier?

A

French scientist who helped develop the field of paleontology

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8
Q

what are fossils are where can they be found

A

Fossils = preserved remains, imprints, or traces of organisms
Can be found in sedimentary rock (in layers / strata)

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9
Q

did georges cuvier believe in catastrophism or gradualism

A

catastrophism

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10
Q

What does each stratum represent

A

Each stratum represents a different catastrophe

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11
Q

What is catastrophism

A

Species had all been wiped out by violent catastrophes. Changes did not arise slowly but through chaotic processes

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12
Q

What is catastrophism opposed to?

A

Gradualism

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13
Q

what is gradualism

A

the theory that Major changes can take place through the cumulative effect of slow but continuous processes

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14
Q

who do you associate with gradualism and what did they postulate ?

A

Hutton & Lyell (geologists) postulated that changes in the Earth’s surface might result from slow, continuous actions (still operating today)

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15
Q

what did lyell believe

A

Lyell: rate of geological processes have not changed throughout history (the world is old)

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16
Q

what did hutton believe

A

Hutton: canyons formed from rivers (proposed gradualism)

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17
Q

what are the aspects of the lamarkian theory of evolution

A

Hypothesized that species evolve through use / disuse & inheritance of acquired traits
CHOOSE WHICH TRAITS GET PASSED ON

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18
Q

why did the lamarkian theory not pass

A

Proposed mechanisms unsupported by evidence

We do not change by striving

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19
Q

What are the aspects of the darwinian theory of evolution

A

Hypothesized that species evolve through the mechanism of natural selection, resulting in increased diversity

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20
Q

what is thee process of darwinians theory of evolution

A

Process:
Genes mutate
Individuals undergo selection
Populations evolve

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21
Q

who was the other scientist with the same theory as Darwin

A

Wallace

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22
Q

What was Darwins journey called and what was its purpose

A

Voyage of the Beagle (1831-1836) to survey life’s “endless forms most beautiful”

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23
Q

where did Darwin go and what animals did he observe ?

A

Travelled to the (geologically new) Galapagos Islands (amongst other locales)
Observed slight variation in phenotypes of finches, mockingbirds, & tortoises by island

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24
Q

what did darwin refer evolution as?

A

descent with modification”

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25
Q

what book did darwin publish

A

ON the origin of species

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26
Q

explain diversity and unity

A

Diversity: conceived of natural history as a branching tree
Unity: similarities between living organisms attributable to descent from a common ancestor

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27
Q

Darwin talked about inheritance but…

A

He Did not yet understand the genetic mechanisms

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28
Q

Was darwins work always accepted?

A

Work was not widely accepted until 20th century

e.g. Scopes Monkey Trial of 1925 (the State of Tennessee v. John Thomas Scopes)

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29
Q

what do the root, branches and tips represent in a phylogenetic tree

A

Root: distant ancestor
Branches: divergence of species
Highest tips: living species

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30
Q

What was the first evolution observation

A

Populations have capacity to produce more offspring than actually survive (if all survived, population would increase exponentially)
But populations tend to be stable (face limited resources & predators) LOOK AT GRAPH ON SLIDES

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31
Q

what was the second evolution observation>

A

Variation exists within a population
These different traits are heritable
Some traits are beneficial & improve the likelihood that an individual will survive & reproduce

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32
Q

what was the first evolution inference

A

Individuals who inherit traits that grant a higher probability of surviving & reproducing will have more offspring (they are more ‘fit’)

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33
Q

what does it mean when an organism is “fit”

A

when an organism inherist traits that grant a higher probability of surviving & reproducing will have more offspring

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34
Q

what was the second evolution inference

A

Differences in reproductive success will result in accumulation of favourable traits (favourable alleles) in the population (over the span of several generations)

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35
Q

what did darwin lack

A

an understanding of inheritance to explain how variation might arise & be transmitted
Still considered the trait blending hypothesis to be true

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36
Q

what did mendel do to help darwins theory

A

Proposed a model of inheritance (discrete heritable units = genes)

37
Q

what is the unit of evolution

A

population

38
Q

what is the most important mechanism for adaptive evolution

A

natural selection

39
Q

what does gradualism explain

A

Gradualism explains big changes as the accumulation of many smaller changes over long time periods

40
Q

what are the 4 pieces of evidence for evolution

A
  • Paleontology (fossil record)
  • Biogeography
  • Comparative anatomy (homology, embryology)
  • Molecular evidence
41
Q

what are the issues with the fossil record

A
  • Soft tissues do not fossilize
  • Soft-bodied organisms are not well represented
  • Can only examine certain parts of organisms (skeletal structure & other hard tissues)
  • Relatively few individuals are actually fossilized
42
Q

what does the fossil record allow us to do

A

examine long-extinct species

43
Q

How can you separate fossils by era?

A

By the Stratification of rock layers allows us to separate fossils by era

44
Q

What can you see through the fossil record and what can it piece togethere

A

See incredible diversity, but also ‘transitional’ forms (succession of forms) in layers where they are expected to be found
Can piece together a roadmap of descent & dead ends

45
Q

what are the two types of dating methods?

A

Relative dating

Radiometric dating (absolute)

46
Q

explain relative dating

A

Relative dating
Use position of fossils in sedimentary rock layers (strata)
The deeper the fossil, the older it is
Not exact, & issues of disturbance

47
Q

explain carbon dating

A

Radiometric dating (absolute)
Use of unstable radioactive isotopes with known half-lives (radioactive decay)
After 1 half life, half of the atoms have become stable decay products
Can compare amount of isotope vs. decay product to determine age

48
Q

the deeper the fossil…

A

the older it is

49
Q

explain carbon dating

A

Use radioactive 14C isotope (forms stable 14N)
Same ratio of 14C:12C in a living organism as in the atmosphere
Can trace through CO2 incorporated into the organism (dead organisms don’t respire)
Over time, 14C:12C ratio will decrease
Works for organic samples younger than ~75,000 years old

50
Q

carbon dating uses what isotope

A

Radioactive 14C isotope to form stable 14N

51
Q

what is the issue with carbon dating

A

only works for samples younger than 75000 years old

52
Q

explain potassium-argon dating

A

Use radioactive 40K isotope (forms stable 40Ar)
Rocks will retain 40K isotope once they solidify from their molten state (gives the time of their formation)
Works for mineral & glass samples between 1,000 years old & a billion years old

53
Q

what isotope does potassium argon use

A

Radioactive 40K isotope (forms stable 40Ar)

54
Q

what is biogeography

A

Study of the geographic distribution of organisms

55
Q

do organisms fill every enrvironmeent that could accommodate them? explain

A

NOO
each species has a unique geographical origin, though some may have dispersed
Each major geographical area has its own distinct flora & fauna

56
Q

each major geographical area has its own distinct….

A

flora and fauna

57
Q

Explain why animals in different places from different ancestors have analogous structures

A

because Some similar animals that have adapted to similar environments have evolved independently from different ancestors – analogous structures

58
Q

What explains why some organisms on certain continents are related to/ressemble organisms on different continents?

A

Continental drift & the presence of land bridges helps

59
Q

what is homology

A

Homology = similarities between organisms due to a common (shared) ancestor

60
Q

how do homologous structures evolve

A

evolved through adaptive radiation (diversified into new forms from a common ancestor)

61
Q

explain adaptive radiation

A

Organisms diversied but have Homologous structures because they come from from a common ancestor)

ORGANISMS WITH SHARED ORIGIN

62
Q

give examples of homologous structures

A

Bat wing, whale fin, & human arm

Reptile eye & mammal eye

63
Q

explain how analogous structures come about

A

They have Structural similarities are due to a similar environment / function

BECause of Convergent evolution (independent origin)

64
Q

explain convergent evolution

A

organisms can have similar/analougous structures because they evolved in similar environments

65
Q

give examples of analogous structures

A

Butterfly wing & bird/bat wing

Octopus eye & human eye

66
Q

What does vestigial mean

A

reduced / degenerate / remnant)

67
Q

why do some structures become vestigial

A

They are not needed, and there is nothing preventing the genes that make them from being lost, so these structures can be lost too

68
Q

give an example of.a structure becoming vestigial

A

Snakes no longer have limbs (they once did), though they still have remnants of the pelvic girdle (from which the legs would have grown)

69
Q

what does Ontology recapitulates phylogeny mean

A

it means development reveals evolutionary history)

70
Q

During development, can embryos show certain traits / structures at certain points that do not appear in the fully developed organism?

A

YES

71
Q

why are some ancestral genes quickly silenced in development

A

Some ancestral genes are quickly silenced (turned off) to prevent those structures from fully developing

72
Q

true or false:Embryos of many different species appear very similar at certain points during their development

A

true

73
Q

give an example of ancestral traits devceloppign and being silenced

A

human embryos go through a stage where they briefly form the start of gills (fish-like), and a stage where the bud of a tail is transiently seen (tadpole-like)

74
Q

Are many genes conserved (shared) between different organisms, though there might be differences in their sequence?

A

Yes

75
Q

The more distantly related the species…

A

the more differences in the sequence

76
Q

do proteins involved in similar processes have homologous sequences? what does this suggest

A

yes, it suggests that these proteins had a common origin)

77
Q

TRUE OR FALSE: Not All organisms use DNA with the same 4 bases and the amino acid code is not shared by all organisms

A

false

78
Q

genes are conserved but what might change about them

A

how and when they function might change

79
Q

is evolution directed? why or why not

A

NO
There is no aim or ultimate goal, no final destination – it is not teleological
Does not necessarily lead to greater complexity

80
Q

true or false: evolution maximizes fitness?

A

false
Evolution does not care about making a “perfect” organism (because it doesn’t care about anything)
It’s all about what works well enough to survive & propagate
What doesn’t work well enough or what isn’t useful is selected out (if there’s strong enough selective pressure)

81
Q

what will decide the prevalence of a trait>

A

the strength of the selective pressure

82
Q

is evolution always conspicuous? explain

Evolutionary changes / adaptation arise over multiple generations

A

no
Small inherited changes may not be easily seen
Not all changes are useful / beneficial

83
Q

true of false: evolution can only happen over long periods of time. why

A

false
Evolution can work over long or short timescales
Some changes occur rapidly if there’s strong selective pressure

84
Q

do populations or individuals evolve

A

populations

85
Q

are Changes within an individual are typically inherited by their offspring? if no, what is the exception?

A

Changes within an individual are not typically inherited by their offspring (unless those changes affect gametes)

86
Q

Does evolution make incremental changes>

A

Small changes built upon small changes over the course of millions of years

87
Q

did we evolve from monkeys? why or why not

A

We did NOT evolve from monkeys or chimpanzees
We have a common ancestor, but we did not come from them
Evolution is NOT a linear path

88
Q

recent changes in humans

A

lactose intolerance
Novel hair & eye colours
Reduced melanin to improve vitamin D synthesis
Spread of sickle cell allele to give resistance to malaria

Biology 101 (15 decks)

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