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9th Grade > Evolution > Flashcards

Evolution Flashcards

1
Q

Evolution

A

A genetic change within a population over time

  1. Species accumulate difference
  2. Descendants differ from their ancestors
  3. New species arise from existing ones
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2
Q

Robert Hooke (1635-1703)

A
  • Concluded fossils are remains of plants and animals
  • Studied mainly “petrified wood”
  • Hypothesized that living organisms had somehow turned into rock
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3
Q

Lamarck’s Explanation for

Evolution

A
  • French scientist (1744-1829)
  • Proposed that similar species descended from a common ancestor (fossil records)
  • Hypothesized that acquired traits were passed on to offspring
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4
Q

Acquired Trait

A
  • Not determined by genes

* Arises during an organism’s lifetime as a result of the organism’s experience or behavior

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5
Q

Thomas Malthus

A
  • “much of human suffering – disease, famine, homelessness and war was the inescapable consequence of the human populations potential to grow much faster than the rate at which supplies of food and other resources could be produced
  • Resources couldn’t keep up with the increase in population 🡪 kept the population number down
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6
Q

Charles Lyell (Scottish Geologist)

A
  • Book: Principles of Geology had a strong influence on Darwin
  • Proposed: gradual forces gradually change Earth’s surface and these forces are still operating today
  • Natural catastrophes are very important in evolution
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7
Q

Darwin – a brief history

A

• Charles Darwin was born on February 12, 1809 in Shrewsbury, England.
• From 1831 to 1836 Darwin served as naturalist aboard the H.M.S. Beagle
on a British science expedition around the world.
• He observed many things 🡪 basis for his ideas

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8
Q

Darwin’s Observations

A
  1. Overproduction of Offspring – species tend to produce excessive numbers of offspring
  2. Heritable Variations – individuals of a population vary extensively in their characteristics and many are inherited
  3. Limited Natural Resources – environmental resources are limited
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9
Q

Alfred Wallace

A
  • Had a theory IDENTICAL to Darwin

* Caused Darwin to publish his Origin of Species by means of natural selection

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10
Q

Natural Selection

A

Natural selection: proposed by Darwin as the mechanism of evolution

  1. individuals have specific inherited characteristics
  2. they produce more surviving offspring
  3. the population includes more individuals with these specific characteristics
  4. the population evolves and is better adapted to its present environment
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11
Q

Darwin’s Theories

A
  1. Descent with Modification – newer forms appearing in fossil records are actually the modified descendants of older species
    - Organisms similar to each other come from a common ancestor while organisms that are more dissimilar share a remote ancestor
  2. Modification by Natural Selection – states HOW evolution occurs
    - Organisms having traits that make them better suited for survival tend to leave more offspring than organisms with fewer beneficial traits
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12
Q

Survival of the “Fittest”

A

Darwin’s theory for how long necks evolved in giraffes

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13
Q

Evidence for Evolution

A
  1. Homologous Structures
  2. Analogous Structures
  3. Vestigial Structures
  4. Embryology
  5. Genetics
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14
Q

Homologous Structures

A

Similar structure; different function

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15
Q

Analogous Structures

A

Similar function; different structure

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16
Q

Vestigial Structures

A

Organ has lost its’ function over time

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17
Q

Embryology

A
  • The study of Embryos and their traits.

* Embryological Structure Similarities means a recent common ancestor.

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18
Q

Genetics

A

Similarities in amino acid chains.

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19
Q

Gene Pools

A
  • Combined genetic information of all the members of a particular population.
  • Relative Frequency of an allele - # of times the allele occurs in a gene pool compared to other alleles.
20
Q

Sources of Genetic Variation

A
  • Mutations – any change in genetic sequence

* Gene Shuffling – crossing over, which occurs during cell division (meiosis)

21
Q

Allele

A

One or two more alternative forms of a gene that arise by mutation and are found on the same place in a chromosome.

22
Q

Traits

A
  1. Single Gene Traits – traits controlled by one gene.

2. Polygenic Traits – traits controlled by two or more genes.

23
Q

Natural Selection: Single Gene Trait

A

Natural selection on single-gene traits can lead to changes in allele frequencies and thus to evolution

24
Q

Natural Selection: Polygenic Traits

A

Natural selection can affect the distributions of phenotypes in any of three ways:

  1. Directional Selection
  2. Stabilizing Selection
  3. Disruptive Selection
25
Q

Adaptive Radiation (Divergent Evolution)

A

Single species or a small group of species have evolved into several different forms that live in different ways.

26
Q

Convergent Evolution

A

Unrelated organisms come to resemble one another

27
Q

Coevolution

A

Two species evolve in response to changes in each other over time

28
Q

Punctuated Equilibrium

A

Long, stable periods interrupted by brief periods of more rapid change

29
Q

Mechanisms of Evolution

A
  1. Genetic Mutation
  2. Gene Flow
  3. Nonrandom Mating
  4. Genetic Drift
  5. Natural Selection
30
Q
  1. Genetic Mutation
A

Polymorphism – two or more distinct phenotypes

Mutations – can be harmful or beneficial

31
Q
  1. Gene Flow
A

Movement of alleles among populations by migration

32
Q
  1. Nonrandom Mating
A

Individuals choose their mates

*Inbreeding – doesn’t change allele frequencies

33
Q
  1. Genetic Drift
A

Changes in allele frequencies in a certain direction

34
Q

Bottleneck Effect

A
  • Example of Genetic Drift
  • Severe reduction in population; reduces overall biodiversity
    • Ex: Cheetahs
35
Q
  1. Natural Selection
A

Formation of a new species

36
Q

Speciation

A
  • Origination of a new species.

* Species – group of organisms that breed with one another and produce fertile offspring.

37
Q

What factors are involved in the

formation of a new species?

A

Gene pools of two populations must becomes separated for them to become new species.

38
Q

Isolating Mechanisms

A
  • As new species evolve, populations become reproductively isolated from each other.
  • When the members of two populations cannot interbreed and produce fertile offspring, reproductive isolation has occurred
39
Q

Behavioral Isolation

A

Behavioral isolation occurs when two populations are capable of interbreeding but have differences in courtship rituals or other reproductive strategies that involve behavior.

40
Q

Geographic Isolation

A

Geographic isolation occurs when two populations are separated by geographic barriers such as rivers or mountains.

41
Q

Temporal Isolation

A

Temporal isolation occurs when two or more species reproduce at different times.

42
Q

Speciation of Finches

A 
Speciation in the Galápagos finches occurred by: 
• Founding of a new population 
• Geographic isolation 
• Changes in new population's gene pool 
• Reproductive isolation 
• Ecological competition
43
Q
  1. Founders Arrive:
A
  • A few finches—species A—travel from South America to one of the Galápagos Islands.
  • There, they survive and reproduce.
44
Q
  1. Geographic Isolation
A
  • Some birds from species A cross to a second island

* The two populations no longer share a gene pool

45
Q
  1. Changes in the Gene Pool
A
  • Seed sizes on the second island favor birds with large beaks
  • The population on the second island evolves into population B, with larger beaks
46
Q

Reproductive Isolation

A
  • If population B birds cross back to the first island, they will not mate with birds from population A
  • Populations A and B are separate species
  • Organisms are unable to breed due to the isolating factors.

9th Grade (2 decks)

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