Speciation Mechanisms: Allopatric and Sympatric Speciation

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Questions and Answers

What is the primary mechanism that prevents gene flow in allopatric speciation?

Errors during cell division

Habitat differentiation

Intersexual selection

Geographical barrier (correct)

What is the result of errors during cell division in sympatric speciation?

Mutation accumulation

Genetic drift

Gene flow

Polyploidy (correct)

What is the term for the process in which an error in mitosis leads to the formation of a new species within one organism?

Sympatric speciation

Allopatric speciation

Allopolyploidy

Autopolyploidy (correct)

What is the adapted feature of the flightless cormorant that allows it to survive and thrive in its environment?

Adapted legs for diving Signup and view all the answers

What is the term for the process in which two separate species contribute to the making of hybrids with extra sets of chromosomes?

Allopolyploidy Signup and view all the answers

What is the result of mutation accumulation in allopatric speciation?

Genetic differences between populations Signup and view all the answers

What is the primary mechanism of reproductive isolation in sympatric speciation?

Habitat differentiation Signup and view all the answers

Which of the following is an example of intersexual selection leading to sympatric speciation?

Funnel web spiders in the Sonoran Desert Signup and view all the answers

What is the key difference between allopatric and sympatric speciation?

The presence of geographical barriers Signup and view all the answers

What is the primary outcome of sympatric speciation?

Formation of new species Signup and view all the answers

Which of the following is NOT a mechanism of sympatric speciation?

Genetic drift Signup and view all the answers

What is the primary characteristic that defines a species in biology?

Interbreeding and producing viable offspring Signup and view all the answers

What is the main reason why two species are considered different according to the biological species concept?

Because of the lack of gene flow between them Signup and view all the answers

What type of reproductive barrier prevents mating between two species due to differences in geographic areas?

Habitat isolation Signup and view all the answers

What is the term for the reproductive barrier that prevents the formation of a zygote or the development of viable offspring?

Post-zygotic barrier Signup and view all the answers

What is the result of reproductive barriers preventing gene flow between two species?

Speciation Signup and view all the answers

What is the term for the reproductive barrier that occurs when the sperm and egg of two species are incompatible, preventing fertilization?

Gametic isolation Signup and view all the answers

What is the consequence of hybrid breakdown?

Weakened or sterile offspring Signup and view all the answers

Which species concept is based on differences in physical characteristics?

Morphological species concept Signup and view all the answers

What is the consequence of reduced hybrid viability?

Prevention of the continuation of the hybrid line Signup and view all the answers

What is the example of hybrids that can survive and reproduce?

Grizzly-polar bear hybrid and the coyote-wolf hybrid Signup and view all the answers

Which species concept is based on differences in habitat preferences and ecological niches?

Ecological species concept Signup and view all the answers

What is the limitation of the biological species concept?

It does not apply to fossils or organisms that reproduce asexually Signup and view all the answers

Study Notes

Speciation refers to the formation of new species, and there are two mechanisms: allopatric speciation and sympatric speciation.
Allopatric speciation occurs when a geographical barrier separates two populations, such as the Grand Canyon separating two species of squirrels, and gene flow is prevented.
Without gene flow, mutations can accumulate, leading to genetic differences between the two populations, causing them to become distinct species over time.
The flightless cormorant of the Galapagos Islands is an example of allopatric speciation, where a mutation led to the development of underdeveloped wings, making it unable to fly and interbreed with other cormorant species.
The legs of the flightless cormorant are adapted for diving, allowing it to survive and thrive in its environment.
Sympatric speciation occurs when two species evolve in the same geographic location, but gene flow is prevented due to mechanisms such as errors during cell division, habitat differentiation, or intersexual selection.
Errors during cell division, such as mitosis, can lead to polyploidy, where an individual has extra sets of chromosomes, making it unable to interbreed with the original species.
Autopolyploidy occurs when an error in mitosis leads to the formation of a new species within one organism, often seen in plants.
Allopolyploidy occurs when two separate species contribute to the making of hybrids with extra sets of chromosomes, leading to the formation of a new species.
Habitat differentiation can lead to sympatric speciation, such as in the case of cichlids from the Americas, where fish with larger heads feed on snails near the shore, while those with smaller heads feed on sediments in deeper waters.
Intersexual selection, where females choose mates with specific traits, can also lead to sympatric speciation, such as in the case of funnel web spiders in the Sonoran Desert, where shy females prefer to mate with shy males, and aggressive males prefer to mate with aggressive females.
Sympatric speciation can occur in the same location, without geographical barriers, but with reproductive isolation due to mechanisms such as habitat differentiation or intersexual selection.
The examples of allopatric and sympatric speciation illustrate the different mechanisms that can lead to the formation of new species.

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Description

Discover the two main mechanisms of speciation: allopatric speciation, where geographical barriers separate populations, and sympatric speciation, where gene flow is prevented despite being in the same location. Learn about the examples and processes that lead to the formation of new species.