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Questions and Answers
What is an example of an endemic species?
What is an example of an endemic species?
- Kangaroos in Australia (correct)
- Fossils of ferns in Antarctica
- Rabbits in South America
- Polar bears in the Arctic
The concept of 'no selection' suggests that if the population is large and mating is random, there will be no variation in traits.
The concept of 'no selection' suggests that if the population is large and mating is random, there will be no variation in traits.
False (B)
What type of selection results in more individuals at the median range and fewer at the extremes of a trait?
What type of selection results in more individuals at the median range and fewer at the extremes of a trait?
Stabilizing selection
Marsupials are primarily found in __________.
Marsupials are primarily found in __________.
Match the types of selection with their descriptions:
Match the types of selection with their descriptions:
What is the main result of disruptive selection?
What is the main result of disruptive selection?
Disruptive selection always results in the formation of new species.
Disruptive selection always results in the formation of new species.
What is a polymorphic population?
What is a polymorphic population?
In a disruptive selection scenario, organisms that cannot reproduce with others in their group are considered to be ______.
In a disruptive selection scenario, organisms that cannot reproduce with others in their group are considered to be ______.
Match the pollinator preference with the type of plant height it favors:
Match the pollinator preference with the type of plant height it favors:
Flashcards
Disruptive Selection
Disruptive Selection
A type of natural selection where extreme phenotypes are favored over intermediate phenotypes, leading to a bimodal distribution of traits in the population.
Polymorphism
Polymorphism
A population with multiple distinct forms or variations of traits, often resulting from disruptive selection.
Speciation
Speciation
The process of the formation of new species from a common ancestor.
Species
Species
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Reproductive Isolation
Reproductive Isolation
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Biogeography
Biogeography
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Endemic Species
Endemic Species
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Natural Selection
Natural Selection
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No Selection
No Selection
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Polygenic Traits
Polygenic Traits
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Study Notes
Patterns in Natural Selection
- No Selection: If a large population experiences random mating with no selective pressure on traits, individuals will display a range of traits. More individuals will exhibit the middle range of a trait (e.g., medium coat length), and fewer will be at the extremes (e.g., short or long coats). Over time, little change occurs in the population.
Stabilizing Selection
- Definition: Selective pressures act against the two extremes of a trait. For example, in plant height, plants that are too short may struggle to compete for sunlight, while extremely tall plants might be more susceptible to wind damage.
- Result: The number of plants with medium height increases, while the number of short and tall plants decreases.
Directional Selection
- Definition: Environmental conditions favour individuals at one extreme of a trait, while the other extreme experiences selection against it.
- Result: The population's trait distribution shifts towards the favoured extreme. (e.g. Giraffe neck length, early selection to taller necks.)
Disruptive Selection
- Definition: Selection pressures act against individuals in the middle of the trait distribution.
- Result: A bi-modal (two-peaked) distribution forms. The two extremes of the trait create their own smaller curves. (e.g. a population with multiple pollinators - for short and tall plants.)
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