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Questions and Answers
Which of the following scenarios best illustrates ecological speciation?
Which of the following scenarios best illustrates ecological speciation?
- Two populations of fish in the same lake start to mate randomly, resulting in a hybrid population with increased genetic diversity.
- A population of birds migrates to a new island with abundant food, leading to an increase in population size, but no new species are formed.
- A group of flowers develops a new color that attracts different pollinators, eventually leading to reproductive isolation from the original population. (correct)
- A population of insects becomes resistant to a pesticide, leading to increased survival rates but no change in mating behavior.
What is the primary difference between allopatric and sympatric speciation?
What is the primary difference between allopatric and sympatric speciation?
- Allopatric speciation involves sexual selection, while sympatric speciation involves reinforcement.
- Allopatric speciation results in hybrids, while sympatric speciation prevents hybrid formation.
- Allopatric speciation occurs with a physical barrier, while sympatric speciation occurs without a physical barrier. (correct)
- Allopatric speciation is driven by natural selection, while sympatric speciation is driven by genetic drift.
How does reinforcement contribute to the process of speciation?
How does reinforcement contribute to the process of speciation?
- By increasing the fitness of hybrid offspring, leading to the merging of two species.
- By promoting gene flow between two populations, increasing genetic diversity and stability.
- By weakening the reproductive barriers between two populations, promoting interbreeding.
- By selecting against hybrid offspring, thus strengthening reproductive isolation between two populations. (correct)
In the context of sexual selection, what is a likely outcome if a population becomes geographically separated and experiences different environmental conditions?
In the context of sexual selection, what is a likely outcome if a population becomes geographically separated and experiences different environmental conditions?
Considering the example of the antelope squirrels separated by the Grand Canyon, which evolutionary mechanism is most directly responsible for their speciation?
Considering the example of the antelope squirrels separated by the Grand Canyon, which evolutionary mechanism is most directly responsible for their speciation?
Why are models like fruit flies useful in the study of speciation?
Why are models like fruit flies useful in the study of speciation?
Which scenario represents a case where parapatric speciation is most likely to occur?
Which scenario represents a case where parapatric speciation is most likely to occur?
How does sexual selection differ from natural selection in driving speciation?
How does sexual selection differ from natural selection in driving speciation?
Which of the following is NOT a typical step in the process of ecological speciation?
Which of the following is NOT a typical step in the process of ecological speciation?
In the example of the fire-bellied and yellow-bellied toads, what evolutionary process is most likely maintaining the distinction between the two species despite inhabiting the same geographic area?
In the example of the fire-bellied and yellow-bellied toads, what evolutionary process is most likely maintaining the distinction between the two species despite inhabiting the same geographic area?
Flashcards
Speciation
Speciation
The formation of a new species based on ecological changes, leading to reproductive isolation.
Allopatric Speciation
Allopatric Speciation
The formation of a new species due to geographic isolation, preventing interbreeding.
Sympatric Speciation
Sympatric Speciation
Speciation occurring without physical separation, but with selective pressures causing divergence within the same area.
Parapatric Speciation
Parapatric Speciation
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Reinforcement
Reinforcement
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Sexual Selection
Sexual Selection
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Hybrid
Hybrid
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Ecological Speciation
Ecological Speciation
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Study Notes
- Speciation is the formation of a new species because of ecological changes.
- These ecological changes cause differences in organisms.
- Natural selection pressures increase favorable changes within a population.
- Speciation occurs when the members of the new species cannot mate and produce fertile offspring with the parent population.
Ecological Speciation
- A new species forms when it can no longer mate with the ancestral population due to ecological changes.
- Species become isolated through physical barriers such as mountain ranges or lakes drying up.
- Isolated species are subject to different selective pressures in their new environment, leading to new traits.
- Natural selection favors new traits that improve mating or survival.
- Speciation happens when the new population can no longer interbreed and produce fertile offspring with the original population.
Types of speciation
- Allopatric speciation involves a geographic change causing physical separation between populations
- This occurs when a population becomes reproductively isolated due to a geographical event.
- Sympatric speciation occurs without physical separation, where selective pressures cause a divide between organisms in the same space.
- Parapatric speciation, a subcategory of sympatric, lacks a physical barrier, but random mating does not occur, and is extremely rare.
- Speciation can occur if an isolated population faces new environmental conditions that favor new traits, preventing reproduction with the original population.
Factors that Lead to Speciation
- Speciation is the formation of new species based on ecological changes, leading to reproductive isolation.
- Speciation occurs when members of an original population can no longer mate and produce fertile offspring.
- Reinforcement and sexual selection can also lead to speciation
Reinforcement
- Reinforcement drives speciation when barriers preventing populations from mating become stronger.
- Hybrid organisms are selected against by natural pressures, such as increased susceptibility to predation.
- The fire-bellied toad and yellow-bellied toad exemplify reinforcement.
- These were once one species, and though they are now distinct, they inhabit the same area in Europe.
- There is a narrow hybrid zone between the two species that have formed and can no longer interbreed.
Sexual Selection
- Sexual selection involves mate choices based on traits, often with females choosing based on physical appearances.
- Males display different courtship behaviors or brighter colors to attract females.
- Males might fight to display dominance.
- Geographic separation can lead to populations favoring different traits, leading to speciation.
- The blue-footed booby and the widowbird are both examples of sexual selection.
- The male blue-footed booby shows the female his blue feet and does a dance.
- Female preference is for very blue feet.
- During mating season, a male widowbird's tail grows significantly, attracting females who prefer longer tails.
Ecological Speciation Examples
- Frog speciation occurred after geographic isolation via continental drift led to new traits suited to new environments, eventually preventing interbreeding with the original population.
- Antelope squirrels in Arizona were separated by the Grand Canyon, leading to different physical characteristics and two separate species: A. harrisii and A. leucurus.
Studying Speciation
- Scientists study speciation through observation of species in natural settings and using models like fruit flies.
- Scientists can simulate different types of speciation in fast-reproducing models.
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