18 Questions
What is the primary focus of the morphospecies concept?
Morphological differences
Which of the following is a weakness of the morphospecies concept?
It does not account for genetic differences
How does the biological species concept define a species?
As a group of interbreeding populations
Which of the following is an example of postzygotic isolating mechanism?
Hybrid inviability
Why is reduced hybrid viability considered a postzygotic isolating mechanism?
It results in the death of hybrid offspring before reaching reproductive age
Which of the following is an example of hybrid sterility as a postzygotic isolating mechanism?
A horse and a donkey producing a sterile mule
What is the primary condition that favors sympatric speciation?
Limited gene flow
Which group of organisms commonly speciates by sympatric speciation?
Flowering plants
Why is sympatric speciation a challenging concept to understand?
It involves speciation without geographic barriers
Which concept defines a species based on observable physical traits?
Morphospecies concept
What is a potential weakness of the morphospecies concept?
It does not account for genetic differences
Why is hybridization a challenge to the Biological Species Concept (BSC)?
It contradicts the concept of reproductive isolation
What is the biological species concept mainly based on?
Genetic differences
What is a major weakness of the biological species concept?
It is difficult to apply to extinct species
How does the biological species concept define a species?
As a group of organisms that can interbreed and produce fertile offspring
What is a postzygotic isolating mechanism?
A mechanism that prevents the hybrid zygotes from developing into viable, fertile adults
Which of the following is an example of postzygotic isolating mechanism?
Hybrid inviability
Why does hybrid inviability pose a challenge to species reproductive success?
It decreases the chances of producing viable, fertile offspring
Study Notes
Species Concepts
- The primary focus of the morphospecies concept is on observable physical traits.
- A weakness of the morphospecies concept is that it may not accurately reflect the genetic differences between species.
Biological Species Concept
- The biological species concept defines a species as a group of interbreeding individuals that are reproductively isolated from other groups.
- The biological species concept is mainly based on reproductive isolation.
Postzygotic Isolating Mechanisms
- A postzygotic isolating mechanism is a reproductive barrier that occurs after the formation of a zygote.
- Examples of postzygotic isolating mechanisms include reduced hybrid viability and hybrid sterility.
- Reduced hybrid viability is considered a postzygotic isolating mechanism because it reduces the chances of hybrid offspring surviving to reproduce.
- Hybrid sterility is an example of a postzygotic isolating mechanism where hybrid offspring are unable to reproduce.
- Hybrid inviability poses a challenge to species reproductive success because it reduces the chances of hybrid offspring surviving to reproduce.
Sympatric Speciation
- Sympatric speciation occurs when a new species emerges from a single population without geographic isolation.
- A primary condition that favors sympatric speciation is the presence of a distinct ecological niche.
- Some groups of organisms, such as insects, commonly speciate by sympatric speciation.
- Sympatric speciation can be a challenging concept to understand because it involves the emergence of a new species within a single population.
Biological Species Concept Weaknesses
- A major weakness of the biological species concept is that it can be challenging to apply in practice, especially in cases where hybridization occurs.
- Hybridization is a challenge to the Biological Species Concept (BSC) because it can blur the boundaries between species.
Test your understanding of speciation with these study questions for Lecture 5. Explore the different concepts of species, prezygotic and postzygotic isolating mechanisms, and the conditions favoring allopatric and sympatric speciation.
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