Evolution Flashcards

1
Q

What is biological evolution?

A

A genetic change in a population over generations

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2
Q

What is fitness?

A

How well an individual is able to reproduce within its environment

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3
Q

What are the components of fitness?

A

Survival + reproductive success

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4
Q

What is sexual selection?

A

Selection of traits that give an individual an advantage in attracting mates, even if these traits are neutral or harmful for survival

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5
Q

What are they types of sexual selection?

A

Intrasexual selection and intersexual selection

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6
Q

What are selection pressures?

A

External agents which affect an individual’s ability to survive and reproduce within an environment

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7
Q

What are biotic selection pressures?

A

Living organisms within the same ecosystem that interact with the affected individual and affect fitness

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8
Q

What are abiotic selection pressures?

A

Non-living factors within an individual’s environment that affects fitness

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9
Q

What are the characteristics of a selection pressure?

A
  • act on all stages of the life cycle
  • may act for many generations
  • act on the phenotype
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10
Q

What is essential for natural selection to occur?

A
  • system of reproduction
  • inherited variation
  • differential reproductive success
  • changing environment
  • selection pressures
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11
Q

What were Darwin’s observations?

A
  1. Organisms have great potential fertility which enables populations to grow exponentially
  2. Natural populations normally do not increase exponentially but remain fairly constant in size
  3. Natural resources are limited
  4. Variation occurs among organisms within a population
  5. Variation is heritable (offspring look like their parents)
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12
Q

What were Darwin’s inferences?

A
  1. A struggle for existence occurs among organisms within populations
  2. Individuals show differential survival and reproduction, favouring advantageous traits (natural selection)
  3. Natural selection, acting over many generations gradually produces new adaptions and new species
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13
Q

When may vestigial organs arise?

A

When a species changes its lifestyle

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14
Q

What are species found in the fossil record known as?

A

Chronospecies (paleospecies)

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15
Q

What is punctuated equilibrium?

A

Evolution consisting of period of no or very little change followed by relatively large changes in a relatively short space of time

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16
Q

What is an example of punctuated equilibrium?

A

Horseshoe crabs have existed unchanged for approximately 250 million years

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17
Q

What were key concepts when Darwin was developing his ideas about evolution?

A

Hutton and Lyde’s ideas that the earth was old and continually changing

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18
Q

How did Darwin describe evolution?

A

“Descent with modification”

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19
Q

What book presented a mechanism for natural selection?

A

The Origin of Species

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20
Q

What is macroevolution?

A

The descent of different species from a common anscestor over many generations

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21
Q

What is micro evolution?

A

Changes in gene frequency in a population from one generation to the next

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22
Q

The genetic code is an example of a ________

A

Homology

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23
Q

What are some examples of biotic selection pressures?

A
  • predation
  • competition
  • disease
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24
Q

What are some examples of abiotic selection pressures?

A
  • climate
  • topography
  • habitat
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25
Q

What are the 3 types of natural selection?

A

Stabilising
Directional
Disruptive

26
Q

What is stabilising selection?

A

Selects against extreme phenotypes

27
Q

What is directional selection?

A

Selects at one end of the phenotype so that the phenotypic character shifts in one direction

28
Q

What is disruptive selection?

A

Selects against average phenotypes

29
Q

What is an example of stabilising selection?

A

Birthweight and infant mortality

30
Q

Who is the selective pressure in artificial selection?

A

Humans, uses the process of natural selection

31
Q

What is intersexual selection?

A

When a female chooses a male mating partner based on a particular trait

32
Q

What is intrasexual selection?

A

When members of the same sex within a population compete with each other in order to gain mating opportunities

33
Q

What is gradualism?

A

Evolution that happens gradually and over a long period of time

34
Q

What is anagenesis?

A

Evolution within a single lineage

35
Q

What is cladogenesis?

A

Branching evolution, where two new species evolve from a common ancestor

36
Q

How do fossils and where fossils are found provide evidence for evolution?

A
  • fossils in deeper layers are older than those above and their position within these rocks gives them a chronological age relative to older or younger fossils
  • fossils of more complex organisms are found in recent rock formations
  • the fossils in older layers will be more simple and primitive
  • the fossils found in newer layers are more diverse and samples than those found on older layers
37
Q

What is an intermediate form?

A

An organism intermediate of two species

38
Q

What is the bird intermediate form?

A

Archaeopteryx

39
Q

What type of evolution is an intermediate form an example of?

A

Cladogenesis

40
Q

What is the fossil record evidence for?

A
  • perpetual change
  • common ancestry
  • intermediate forms
  • cladogenesis
  • anagenesis
  • evolutionary failure
  • evolutionary stability
41
Q

What is comparative anatomy?

A

The study of similarities and differences in the anatomy of different species

42
Q

What are analogies the result of?

A

Convergent evolution

43
Q

What are homologous traits?

A

Traits that share an underlying similarity due to common ancestry and divergent evolution

44
Q

What is adaptive radiation?

A

Process whereby rapid cladogenesis is seen, if new niches become available to a species

45
Q

What are analogous structures?

A

Traits that have the same appearance, structure or function but have evolved separately due to convergent evolution

46
Q

What is a vestigial feature?

A

Features that become reduced because they no longer perform a function

47
Q

What do features become vestigial?

A

Structures that are large but have no function wastes metabolic energy to maintain

48
Q

How do analogous features evolve?

A

Independently through similar environmental selection pressures

49
Q

What is convergent evolution?

A

Seperate lineages that were quite different become similar because of similar lifestyles

50
Q

What are homoplastic features?

A

Features that are similar in appearance, may or may not be homologous or analogous

51
Q

What are atavistic structures?

A

When an ancestral trait reappears in a species after being lost through evolutionary change

52
Q

What is an example of an atavistic feature?

A

A horse being born with additional toes

53
Q

In what ways is artificial selection evidence for evolution?

A
  • variation in populations
  • descent with modification
  • rapid change
  • mechanism of evolution
54
Q

What is a phylogenetic constraint?

A

Refers to the limitations of future evolutionary pathways that have been imposed by previous adaptions

55
Q

What is an example of a phylogenetic constraint?

A

Terrestrial vertebrates have a body plan that consists of four limbs

56
Q

What is comparative embryology?

A

The comparison of embryo development across species

57
Q

In what ways may a peacocks tail reduce survival?

A
  • it is very large and unwieldy so it requires more energy to drag around, energy that could be better used for just staying alive
  • it is very visible so males are potentially more visible to predators and less able to escape quickly with such a bulky tail
  • it is very costly to grow, again using energy that could be used elsewhere
58
Q

How can a peacocks tail can actually result in an increase in fitness even though the survival of the individual may be compromised?

A
  • fitness consists of survival and fertility
  • if the increase in fertility through the ability to attract multiple mates outweighs the decrease in survival, then overall fitness is increased
59
Q

In what ways might a peacocks tail potentially increase that individual’s reproductive success?

A
  • it acts as a sensory cue imparting information about a male’s mating value (in terms of the quality of his genes) to peahens who then mate preferentially with the male with the best tail
  • the male with the best tail ends up with more partners compared to other males in the population, which can result in more offspring
60
Q

Why are analogies present?

A

Because two species share a common lifestyle

61
Q

What is fitness?

A

The ability for an individual to survive and reproduce so that it’s genes are passed onto the next generation

62
Q

What is punctuated equilibrium?

A

Rapid evolution followed by long periods of little or no change