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Biology 1B > Evolution > Flashcards

Evolution Flashcards

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1
Q

What are 5 pieces of evidence that helped Darwin and Wallace to propose the theory of evolution by natural selection?

A
  • Observations of artificial selection
  • Fossil record
  • Biogeography
  • Homologies
  • Adaptions to environment
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2
Q

How did observations of artificial selection help Darwin and Wallace propose the theory of evolution by natural selection?

A
  • Humans had selectively bred plants and animals to produce desired traits
  • If humans could selectively breed organisms, nature could also select for advantageous traits
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3
Q

How did observations of fossil record help Darwin and Wallace propose the theory of evolution by natural selection?

A
  • Different layers of rock contained different kinds of fossils
  • Life has changed over time
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4
Q

How did observations of biogeography help Darwin and Wallace propose the theory of evolution by natural selection?

A
  • Species on different continents often had similarities, however were also different in significant ways
  • Suggests that they share a common ancestor, but after continents split apart they evolved separately
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5
Q

How did observations of homologies help Darwin and Wallace propose the theory of evolution by natural selection?

A
  • Different species have similar structures, such as bones in wings of birds and human arms
  • Similarities due to common ancestry
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6
Q

How did observations of adaptions help Darwin and Wallace propose the theory of evolution by natural selection?

A
  • Organisms are well-suited to their environments
  • Example being finches on Galapagos Islands
  • Indicated that natural selection had acted to produce adaptions that helped them survive in particular environments
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7
Q

What is Lamarckian evolution?

A
  • The idea that organisms can pass on acquired traits to their offspring
  • Discredited by modern science
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8
Q

What is evolution by natural selection?

A
  • Proposed by Darwin and Wallace
  • Suggests that species change over time due to natural selection acting on variation within populations
  • Widely accepted scientifically
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9
Q

What are the 5 main mechanisms that cause evolution in populations?

A
  • Mutations
  • Gene flow
  • Genetic drift
  • Natural selection
  • Non-random mating
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10
Q

How do mutations cause evolution?

A
  • Spontaneous changes in DNA sequence can introduce/change particular phenotypic traits
  • Can increase/decrease likelihood of survival
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11
Q

What is gene flow?

A
  • Movement of alleles from one population to another
  • Result of migration, interbreeding or other forms of genetic exchange
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12
Q

What is genetic drift?

A
  • Random fluctuation of allele frequencies in a population due to chance events
  • E.g. founder effect or bottleneck effect
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13
Q

What is the founder effect?

A

Where a small fraction of the population becomes geographically isolated from the rest, causing a reduced genetic diversity in that group

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14
Q

What is the bottleneck effect?

A

Where only a small fraction of the population survives (e.g. a natural disaster), causing a reduced genetic diversity in that group

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15
Q

What is non-random mating?

A

Individuals with particular traits are more likely to mate

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16
Q

What is natural selection?

A

The process by which certain traits that give a selective advantage are more likely to be passed on to future generations, while traits that are disadvantageous are less likely to be passed on

17
Q

What is directional selection?

A

When individuals with traits on one side of the mean in their population survive better or reproduce more than those on the other

18
Q

What is disruptive selection?

A

When more extreme phenotypes (or genotypes) within a population have a fitness advantage over intermediate individuals

19
Q

What is continuous variation?

A
  • Continuous variation refers to characteristics that can have many different values a range (e.g. height)
  • Majority of continuous traits are around the mean
20
Q

What is discrete variation?

A
  • Discrete variation refers to characteristics that fit into distinct categories (e.g. colour)
  • Discrete traits will be shown as multiple peaks
21
Q

What is ‘fitness’ in natural selection?

A
  • Fitness refers to an organisms’ ability to survive and reproduce
  • It is often used as a measure of how well adapted an organism is to its environment
22
Q

What is sexual selection?

A
  • A type of natural selection that occurs when individuals within a population differ in their ability to attract mates
  • Traits such as courtship displays or physical characteristics that indicate genetic quality to mates are more likely to be passed on
23
Q

What are biological species?

A

Defined based on their ability to breed and produce fertile offspring

24
Q

What are morphospecies?

A

Defined based on observable physical characteristics

25
Q

When are morphospecies commonly used?

A

Often used for grouping organisms that do not reproduce sexually (such as bacteria)

26
Q

What are the two distinct patterns of evolutionary change?

A

Anagenesis and cladogenesis

27
Q

What is anagenesis also known as?

A

Phyletic evolution

28
Q

What is anagenesis?

A
  • Refers to the gradual transformation of a single lineage over time
  • A species or a group of related species evolves gradually and continuously, accumulating changes over time
  • Can result in the emergence of a new species or in the extinction of the original species.
29
Q

What is cladogenesis also known as?

A

Branching evolution

30
Q

What is cladogenesis?

A
  • Refers to the splitting of lineage into two or more distinct lineages, each of which evolve independently over time
31
Q

How does cladogenesis occur?

A

Through speciation events, such as allopatric or sympatric speciation

32
Q

What is allopatric speciation?

A
  • Occurs when biological populations become geographically isolated from each other
  • Populations diverge genetically to the point whether they no longer can interbreed
33
Q

What is sympatric speciation?

A
  • Occurs when two or more distinct species arise from a single ancestral species in the absence of a physical barrier
  • Can occur due to diversifying selection, where extreme values for a trait are favoured over intermediate values

Biology 1B (6 decks)

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