Formation of New Species and Speciation Types
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Questions and Answers

What distinguishes Cope's gray treefrog from the common gray treefrog in overlapping regions?

  • Male mating call speed (correct)
  • Size of the frogs
  • Habitat preferences
  • Coloring patterns

Which of the following mechanisms is associated with sympatric speciation?

  • Geographic isolation
  • Sexual selection (correct)
  • Hybrid vigor
  • Allopatric speciation

What are the potential outcomes of hybridization according to the content?

  • Reinforcement, fusion, and stability (correct)
  • Creation of completely new species only
  • Hybridization leading to extinction
  • Mainly reproductive isolation

Which of the following describes punctuated equilibria?

<p>Rapid bursts of speciation followed by stability (A)</p> Signup and view all the answers

How many chromosomes does Hyla versicolor possess?

<p>48 chromosomes (D)</p> Signup and view all the answers

What occurs when prezygotic barriers fail in the context of mallard ducks?

<p>Increased hybridization (C)</p> Signup and view all the answers

What is the primary mechanism for sympatric speciation mentioned?

<p>Habitat differentiation (C)</p> Signup and view all the answers

What does polyploidy result from?

<p>Meiotic failure (C)</p> Signup and view all the answers

Which type of polyploidy occurs when an organism has more than two sets of chromosomes derived from a single species?

<p>Autopolyploidy (C)</p> Signup and view all the answers

What role does ecological niche play in sympatric speciation?

<p>It allows species to exploit resources differently. (B)</p> Signup and view all the answers

What is a consequence of polyploidy in plants?

<p>Creation of novel species (D)</p> Signup and view all the answers

What is sexual selection?

<p>Preference by one sex for specific traits in the other sex (A)</p> Signup and view all the answers

How do empty ecological niches influence speciation?

<p>They provide opportunities for diversification. (C)</p> Signup and view all the answers

What is the primary distinction between allopatric speciation and sympatric speciation?

<p>Allopatric speciation involves geographic isolation, while sympatric speciation does not rely on geographic barriers. (D)</p> Signup and view all the answers

Which species concept defines a group based on anatomical characteristics that can be measured?

<p>Morphological species concept (C)</p> Signup and view all the answers

What type of barrier serves to prevent hybridization before fertilization occurs?

<p>Prezygotic barrier (B)</p> Signup and view all the answers

Which of these terms describes a situation where hybrid offspring are viable but sterile?

<p>Postzygotic isolation (C)</p> Signup and view all the answers

The ecological species concept defines species in terms of what characteristic?

<p>Ecological roles or niches (B)</p> Signup and view all the answers

What does the term 'phylogenetic species concept' refer to?

<p>A group of organisms with a unique genetic history. (C)</p> Signup and view all the answers

Which of the following is a common mechanism that may cause prezygotic barriers?

<p>Different mating seasons (C)</p> Signup and view all the answers

How does allopatric speciation primarily arise?

<p>By geographic barriers segregating ancestral populations. (A)</p> Signup and view all the answers

Which of the following does NOT characterize a postzygotic barrier?

<p>Failure of fertilization. (B)</p> Signup and view all the answers

What is the significance of 'Rassenkreis' in the study of speciation?

<p>It indicates a group of races with potential interbreeding. (A)</p> Signup and view all the answers

Flashcards

Sympatric Speciation

The process where two species evolve from a common ancestor while living in the same geographic area.

Sexual Selection

A type of sympatric speciation where individuals within a population develop preferences for different traits, leading to reproductive isolation.

Habitat Differentiation

A type of sympatric speciation where genetic changes allow individuals to exploit different resources within the same environment.

Hybridization Outcomes

The process where two species interbreed and their offspring either merge into a single species, become distinct species, or maintain a hybrid zone.

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Punctuated Equilibria

A model of evolution suggesting that species change rapidly in short bursts, followed by long periods of stasis.

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Species

A group of organisms whose members possess similar anatomical characteristics and have the ability to interbreed.

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Biological Species Concept

A group of populations whose members have the potential to interbreed in nature and to produce viable and fertile offspring with each other, but not with members of other such groups.

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Morphological Species Concept

Defining species by measurable anatomical criteria.

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Paleontological Species Concept

Defining species based on morphological differences known only from the fossil record.

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Ecological Species Concept

Defining species in terms of ecological roles (niches).

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Phylogenetic Species Concept

A set of organisms with a unique genetic history, representing a single branch on the tree of life.

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Allopatric Speciation

Speciation that occurs when a population is divided by a geographic barrier.

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Prezygotic Barriers

Evolutionary adaptations that prevent hybridization before fertilization.

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Postzygotic Barriers

Biological accidents that can result in decreased or zero fitness of hybrid offspring.

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Ecological Niche

The unique environmental role of a species, encompassing all resources used and habitat aspects that allow it to thrive.

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Polyploidy

A mechanism for sympatric speciation where a mutation results in an offspring with more than two sets of chromosomes.

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Autopolyploidy

A type of polyploidy resulting from the duplication of chromosomes within a single species.

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Allopolyploidy

A type of polyploidy resulting from the hybridization between two different species, followed by chromosome doubling.

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Adaptive Radiation

A type of speciation where new species arise from a common ancestor in an environment with diverse opportunities and challenges.

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Cryptic Species

A phenomenon where two similar species coexist without interbreeding, despite the absence of physical barriers.

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Study Notes

Formation of New Species

  • Species are groups of organisms with similar anatomy and the ability to interbreed.
  • Different species concepts exist, including biological (ability to interbreed in nature), morphological (measurable anatomical features), paleontological (differences seen in the fossil record), ecological (species roles/niches), and phylogenetic (unique genetic history).

Types of Speciation

  • Allopatric speciation: A population is geographically separated. This leads to the development of distinct populations that no longer interbreed, thus creating new species.
  • Sympatric speciation: A population develops new species within the same geographic area. This can occur through various mechanisms.

Mechanisms for Sympatric Speciation

  • Polyploidy: An individual has more sets of chromosomes than typical. This may result from errors during meiosis, which is related to forming gametes. This new combination leads to reproductive isolation.
  • Sexual selection: Preference by one sex for traits in the other sex. This leads to the diversification of the population due to mating choices.
  • Habitat differentiation: Mutations allow individuals in a population to exploit different resources within the same environment leading to a new species.

Reproductive Isolation

  • Prezygotic barriers: Prevent fertilization from occurring.
    • Habitat isolation: Species occupy different habitats, minimizing contact.
    • Temporal isolation: Different mating seasons or times of day.
    • Behavioral isolation: Different courtship rituals.
    • Mechanical isolation: Physical incompatibility between reproductive organs.
    • Gametic isolation: Incompatibility between eggs and sperm.
  • Postzygotic barriers: Occur after fertilization.
    • Reduced hybrid viability: Offspring do not develop or survive.
    • Reduced hybrid fertility: Offspring are infertile.
    • Hybrid breakdown: Offspring of hybrids have reduced fitness or are infertile.

Outcomes of Hybridization

  • Reinforcement: Selection strengthens prezygotic isolating mechanisms.
  • Fusion: Reproductive barriers weaken, leading to a single species.
  • Stability: Hybrids continue to be formed, demonstrating the balance within a hybrid zone.

Modes of Speciation

  • Punctuated Equilibrium: Speciation occurs in rapid bursts followed by long periods of stability, unlike gradualism.
  • Both gradualism and punctuated equilibrium describe possible speciation pathways.

Polyploidy

  • Autopolyploidy: A duplication of chromosome sets within a species.
  • Allopolyploidy: Combining chromosome sets from two species.

Polyploid Plants

  • Polyploidy can result in new crop species, which are important sources of food.

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Chapter 18B Formation of New Species PDF

Description

Explore the fascinating concepts of how new species are formed through various mechanisms. Understand the differences between allopatric and sympatric speciation, along with the processes that contribute to speciation, including polyploidy. This quiz covers essential concepts critical to the study of evolutionary biology.

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