Text Chapter 8: Evolution and Natural Selection Flashcards Preview

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Flashcards in Text Chapter 8: Evolution and Natural Selection Deck (26):
1

Observations that Led Darwin to Form his Theory of Evolution

-living organisms resemble extinct fossil organisms
-progressive changes from simpler to more complex organisms can be seen in the fossil record
- different island species resemble each other
-island populations resemble those on nearby islands
-lands with similar climates have unrelated plants and animals
-plants and animals of each continent are distinctive

2

Observations Reached in the Flowchart of Evolutionary Reasoning

-potential for rapid reproduction
-relatively constant resources and population over time
-variability in structures and behaviors
-some variability is inherited

3

Conclusions Reached in the Flowchart of Evolutionary Reasoning

-competition for survival and rapid reproduction
-natural selection- on average, the fittest organisms leave the most offspring
-evolution- the genetic makeup of the population changes over time driven by natural selection

4

Conclusions Reached in the Flowchart of Evolutionary Reasoning

-competition for survival and rapid reproduction
-natural selection- on average, the fittest organisms leave the most offspring
-evolution- the genetic makeup of the population changes over time driven by natural selection

5

Adaptation

a trait that makes a species survival more likely

6

Evolution

a change in the characteristics of organisms over time

7

Natural Selection

the mechanism for evolution, the fittest organism survive

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Three Conditions Required for Natural Selection

1. variations for a trait- different versions of a trait are found in a population
2. heritability- variations on the trait are passed from parents to offspring
3. differential reproductive success- individuals best adapted to the environment leave the most offspring

9

Three Conditions Required for Natural Selection

1. variations for a trait- different versions of a trait are found in a population
2. heritability- variations on the trait are passed from parents to offspring
3. differential reproductive success- individuals best adapted to the environment leave the most offspring

10

Analogous Structures

superficially similar, do not show a common origin

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Homologous Structures

same evolutionary origin despite differences in function

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Directional Selection

increases one extreme

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Stabilizing Selection

eliminates both extremes

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Disruptive Selection

increases both extremes

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Disruptive Selection

increases both extremes

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Evidence for Evolution after Darwin

-fossil record
-geological (sufficient time for evolution based on age of earth)
-comparative anatomy (analogous, homologous, vestigial structures)
-embryology (similar embryonic patterns of development)
-biochemistry (molecular similarities between different organisms)
-genetics (mutation generates diversity, meiosis and fertilization generate new combinations due to crossing over, alternate patterns of chromosome segregation, unique genotype of fertilizing sperm combined with unique genotype of egg)

17

Evidence for Evolution after Darwin

-fossil record
-geological (sufficient time for evolution based on age of earth)
-comparative anatomy (analogous, homologous, vestigial structures)
-embryology (similar embryonic patterns of development)
-biochemistry (molecular similarities between different organisms)
-genetics (mutation generates diversity, meiosis and fertilization generate new combinations due to crossing over, alternate patterns of chromosome segregation, unique genotype of fertilizing sperm combined with unique genotype of egg)

18

Ways in which Scientists can Observe Natural Selection in Action Today

artificial selection (dog breeds)
-insecticide resistance (in western corn rootworm larvae)

19

Major Sources of Genetic Variability

-mutation generates diversity
-meiosis and fertilization generate new combinations due to:
crossing over, alternate patterns of chromosome segregation, unique genotype of fertilizing sperm combined with unique genotype of egg

20

Describe how Natural Selection Contributes to Evolution

the fittest offspring survive, over time makes organisms best suited to their environment

21

Describe how Natural Selection Contributes to Evolution

the fittest offspring survive, over time makes organisms best suited to their environment

22

Mutation

an alteration in the base-pair sequence in the DNA of an individual’s gamete- producing cells that changes an allele’s frequency

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Genetic Drift

a random change in allele frequencies, unrelated to any allele’s influence on reproductive success

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Migration (gene flow)

a change in allele frequencies caused by individuals moving in or out of a population

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Natural Selection

a change in allele frequencies that occurs when individuals with one version of a heritable trait have greater reproductive success than individuals with a different version of the trait.

26

Describe the types of color and pattern adaptations that can arise as a result of natural selection

organisms adapt to camouflage to their environment to hide from predators, or become brightly colored to ward off predators