BIOL 424 Module 3 Handout Quiz (Easy)
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Questions and Answers

What did Charles Darwin describe as the 'mystery of mysteries'?

  • The formation of new species (correct)
  • The classification of organisms
  • The extinction of species
  • The process of natural selection

What is necessary to study the process of speciation?

  • A detailed history of genetic mutations
  • A clear definition of what constitutes a species (correct)
  • Knowledge of environmental changes
  • A comprehensive fossil record

What are species described as, according to current understanding?

  • Homogeneous groups with identical genetics
  • Fixed entities with no variation
  • Groups of individuals that maintain observable discontinuities (correct)
  • Population clusters that rarely interbreed

What is indicated by the term 'reproductive isolation' (RI)?

<p>A mechanism that prevents species from interbreeding (B)</p> Signup and view all the answers

How does the idea of gaps among species evolve according to Darwin's contributions?

<p>They are dynamic and continuously created (D)</p> Signup and view all the answers

Which of the following factors is crucial in the study of speciation?

<p>Recognizing the mechanisms of gene flow and traits causing RI (A)</p> Signup and view all the answers

What is the relationship between speciation and gene flow?

<p>Gene flow can lead to reproductive isolation (C)</p> Signup and view all the answers

What type of speciation is primarily examined in the current understanding of evolutionary processes?

<p>Geographically defined speciation (C)</p> Signup and view all the answers

What does the presence of 'gaps' between diverged taxa signify?

<p>They represent unique traits that differentiate species. (A)</p> Signup and view all the answers

Why is it problematic to draw a hard line when defining species?

<p>Populations often have varying degrees of gene flow. (C)</p> Signup and view all the answers

What is a key aspect to understand in speciation?

<p>The traits and factors causing reproductive isolation. (A)</p> Signup and view all the answers

What challenges does geographic variation within taxa create?

<p>It complicates global population clustering. (B)</p> Signup and view all the answers

What role does gene flow play in defining species?

<p>It creates confusion in genealogical definitions. (D)</p> Signup and view all the answers

What is the main pursuit in understanding speciation?

<p>Understanding the traits causing reproductive isolation. (C)</p> Signup and view all the answers

What does ongoing polymorphism within populations suggest?

<p>Genetic variation and potential gene flow. (D)</p> Signup and view all the answers

How might named species be perceived due to gene flow?

<p>As human constructs of convenience. (C)</p> Signup and view all the answers

What is prezygotic reproductive isolation (RI)?

<p>It prevents gene flow before mating. (B)</p> Signup and view all the answers

Which of the following describes noncompetitive gametic isolation?

<p>Gametes cannot unite due to poor transfer of sperm. (C)</p> Signup and view all the answers

How can prezygotic RI affect speciation?

<p>By generating assortative mating. (C)</p> Signup and view all the answers

What occurs during gametic isolation?

<p>Gametes of different species fail to unite. (D)</p> Signup and view all the answers

What type of postzygotic RI is linked to external factors affecting hybrids?

<p>Extrinsic isolation. (D)</p> Signup and view all the answers

Which statement is true about intrinsic postzygotic isolation?

<p>It does not depend on external conditions. (D)</p> Signup and view all the answers

What role do pollinators play in prezygotic RI?

<p>They affect pollen transfer and assortative mating. (A)</p> Signup and view all the answers

What defines postzygotic reproductive isolation?

<p>It occurs after zygote formation. (B)</p> Signup and view all the answers

What is the main factor that led to the formation of the apple host race of the fly?

<p>Shift to attacking apples sympatrically (C)</p> Signup and view all the answers

Which mode of speciation is characterized by populations evolving in overlapping geographic areas?

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

What was proposed by Bush regarding the R.pomonella sibling species group?

<p>It developed through various modes of speciation (D)</p> Signup and view all the answers

What are the potential consequences of traits adapting individuals to one habitat when they migrate to another?

<p>Reduction in survivorship and fertility (B)</p> Signup and view all the answers

How may the geographic distribution of populations change during speciation?

<p>It may shift between allopatry, parapatry, and sympatry (B)</p> Signup and view all the answers

What is the term used for speciation that is influenced by hybrid ancestry and reduced fitness?

<p>Mutation order speciation (B)</p> Signup and view all the answers

What is the significance of opsin genes in the context of parapatric divergence?

<p>They allow vision in varying water depths (D)</p> Signup and view all the answers

Why is it difficult for intrinsic reproductive isolation (RI) to evolve in sympatric populations?

<p>Adaptation to the same ecological conditions (C)</p> Signup and view all the answers

What does RI stand for in the context of speciation?

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

What does the strict categorization of speciation modes not always reflect?

<p>The complexity of evolutionary processes (A)</p> Signup and view all the answers

Where is the evolution of D-M incompatibilities more likely to occur?

<p>In isolated allopatric populations (B)</p> Signup and view all the answers

What type of external factors can contribute to divergent ecological selection pressures?

<p>Biotic and abiotic factors (C)</p> Signup and view all the answers

In what type of divergence do populations remain in contact but adapt to different ecological niches?

<p>Parapatric divergence (D)</p> Signup and view all the answers

What complicates the identification of candidate loci in speciation studies?

<p>Complex environmental interactions (C)</p> Signup and view all the answers

Which statement best describes an effect of divergent ecological selection on hybrid populations?

<p>It can cause D-M incompatibilities in hybrids (B)</p> Signup and view all the answers

What must be established to discern the evolutionary chronology of reproductive isolation?

<p>Natural history details of populations (D)</p> Signup and view all the answers

What characterizes parapatric speciation?

<p>Populations adapt to different ecological habitats (A)</p> Signup and view all the answers

How does the rate of gene flow in parapatric speciation compare to other modes of speciation?

<p>Higher than in allopatric speciation but lower than in sympatric speciation (C)</p> Signup and view all the answers

What presents a challenge in verifying parapatric speciation?

<p>Historical data of past species ranges is often missing (D)</p> Signup and view all the answers

What is indicated by the term 'transporter' speciation?

<p>Adaptive divergence using recycled genetic variation (B)</p> Signup and view all the answers

Which of the following best describes the process involved in the divergence of taxa in parapatric speciation?

<p>Populations accumulate genetic differences while overlapping (B)</p> Signup and view all the answers

What is a key aspect of reproductive isolation (RI) models relevant to parapatric speciation?

<p>They evolve through varying combinations of factors and modes (B)</p> Signup and view all the answers

How do historical patterns of species ranges inform our understanding of speciation?

<p>They may indicate whether taxa share a parapatric relationship or have undergone secondary contact (A)</p> Signup and view all the answers

Which organism examples are related to the concept of transporter speciation?

<p>Cichlid fish in Africa (B)</p> Signup and view all the answers

Flashcards

Speciation

The process of forming new and distinct species in the course of evolution.

Species Definition

A crucial concept for studying speciation; defining how one species differs from another.

Reproductive Isolation

The evolution of genetic barriers to gene flow, preventing formerly interbreeding populations from interbreeding.

Gene Flow

The transfer of genetic material between populations of the same species.

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Darwin's Species Definition

Groups of individuals that maintain observable discontinuities in diversity when co-occurring.

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Dynamic Species

Species are not static; they are constantly changing and created over time.

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Modes of Speciation (Geographically Defined)

Different ways in which new species form, often based on geographic factors.

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Mystery of Mysteries

A reference to species formation being one of the least understood aspects of evolution.

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Species definition

Determining when two populations are considered separate species. It's complex and not universally agreed upon.

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Geographic overlap and species

Whether populations must completely overlap geographically to be considered different species. There's no single, easy answer.

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Genotypic clusters

Groups of organisms sharing similar genetic characteristics. A key factor in considering species delineation.

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Speciation

The process by which new species arise from existing ones. Understanding what causes genetic differences within populations is critical

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Gene flow

The exchange of genetic material between populations. Can complicate defining species.

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Phylogenetic clades

Groups of organisms sharing a common ancestor. A way to classify species using evolutionary relationships.

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Longstanding polymorphism

Genetic variation that has persisted within a population for a long time. A factor that might delay speciation

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Majority rule in species decision

Determining species status based on a majority vote or consensus among groups.

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Prezygotic Reproductive Isolation

A type of reproductive isolation that occurs before fertilization, preventing the formation of a zygote.

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Postzygotic Reproductive Isolation

A type of reproductive isolation that occurs after fertilization, resulting in the formation of inviable or sterile offspring.

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Gametic Isolation

A type of prezygotic isolation where the gametes (sperm and egg) of two species fail to unite due to incompatibility.

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Noncompetitive Isolation

A type of gametic isolation where the transfer of sperm is poor or gametes die in the reproductive tract of the female.

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Extrinsic Postzygotic Isolation

Postzygotic isolation due to negative interactions of hybrids with external environmental conditions.

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Intrinsic Postzygotic Isolation

Postzygotic isolation due to genomic incompatibilities between species, independent of external factors.

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Assortative Mating

Mating preference for similar traits.

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Speciation with Gene Flow

Speciation occurring even with some continued gene exchange between populations.

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Sympatric Speciation

Formation of new species in the same geographic area.

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Parapatric Divergence

New species evolve in geographically adjacent but not completely overlapping ranges.

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Host Shifts

A species adapting to a new host, which can lead to speciation.

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Allopatric Speciation

Formation of new species through geographic isolation.

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Ecological Divergence

Populations differentiating based on ecological factors.

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Sibling Species

Species that are very similar in appearance but genetically distinct.

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Geographic Distribution

The area where a species is found.

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Adaptive Radiation

A process in which multiple species evolve from a common ancestor in a relatively short period.

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Parapatric Speciation

Species formation where populations live in adjacent areas but still partially overlap, leading to adaptation to different habitats or mutations.

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Gene Flow

The transfer of genes between populations.

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Introgression

The transfer of genetic material between species.

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Allopatric Speciation

Species formation where populations are geographically isolated leading to little or no gene flow.

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Sympatric Speciation

Species formation without geographic isolation, e.g. due to niche divergence

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Reclassification of RI models

Shifting how we classify reproductive isolation (RI) from a framework based mainly on geographic location to include other speciation mechanisms.

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Standing genetic variation

Pre-existing genetic differences within a species population that can be 'recycled' to contribute to new adaptation and speciation.

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Historical data for species ranges

Data about past geographic distributions of species, crucial but often missing, in studying parapatric speciation

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Reduced Fitness in Hybrids

Migrants and hybrids between differing populations have lower survival, reproduction, and mate attraction.

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Divergent Ecological Selection

Different selection pressures (like food, climate, or interactions) cause trait differences between populations.

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Intrinsic Postzygotic Isolation

Genetic incompatibility making hybrid offspring less fit, regardless of environment.

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Sympatric Speciation Difficulty

In the same area, it's hard for populations to evolve reproductive isolation due to shared environmental pressures.

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Allopatric Speciation Advantage

Reproductive isolation is more easily established in separate populations initially.

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D-M Incompatibilities

Genetic incompatibilities, often arising from divergent selection, affecting hybrid individuals.

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Role of Selection in Speciation

Selection pressures drive divergence and lead to genetic differences, crucial to species formation.

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Speciation Genes

Genes associated with reproductive isolation, identified in patterns of molecular evolution.

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Study Notes

Modes and Mechanisms of Speciation

  • Speciation is the evolutionary process where a group of inbreeding populations diverges into two or more reproductively isolated groups
  • There are about 8.7 million eukaryotic species on Earth
  • Species are fundamental units of biodiversity
  • Darwin described the formation of new species as the "mystery of mysteries"
  • Reproductive isolation is the barrier of reproduction and gene exchange between different incipient species; occurring before or after zygote formation
  • Prezygotic isolation occurs before zygote formation (before fertilization)
  • Postzygotic isolation occurs after zygote formation (after fertilization)

Classifying Barriers to Gene Flow

  • Prezygotic isolation: Barriers to gene flow that occur before the formation of a zygote

    • Temporal isolation: Differences in timing of breeding seasons or times of activity
    • Mating isolation: Differences in mating signals (e.g., calls, dances, pheromones) or mating behaviors that prevent interbreeding
    • Habitat isolation: Differences in the habitats where species live (e.g., different ecological niches)
    • Behavioral isolation: Differences in courtship rituals or other behaviors that prevent interbreeding
    • Pollination in plants: Differences in flower structure, pollination mechanisms or timing
    • Mechanical isolation: Differences in reproductive structures prevent successful mating
    • Gametic isolation: Differences in gamete structures or chemical signals that prevent successful fertilization

  • Postzygotic isolation: Barriers to gene flow that occur after the formation of a zygote

    • Intrinsic postzygotic isolation occurs internally and is independent of the environment
      • Genomic incompatibilities between species result in hybrid inviability (unsuccessful development) or sterility (unsuccessful reproduction)
    • Extrinsic postzygotic isolation are influenced by the environment; meaning hybrids have lower fitness in the wild

Modes of Speciation

  • Allopatric speciation: Populations are geographically separated, preventing gene flow
    • Peripatric speciation: Occurs when a small population breaks off from the main population and forms new specie in a new habitat.
  • Sympatric speciation: Populations live in the same geographic area, but still diverge
  • Parapatric speciation: Populations diverge while in contact along a geographic boundary.

Evolutionary Mechanisms Causing Population Divergence

  • Natural selection: Selection pressures in different environments cause populations to evolve different traits.
  • Sexual selection: Individuals with traits that are attractive to the opposite sex are more likely to reproduce, leading to divergence in mating preferences.
  • Hybrid, Polyploid, and Homoploid Speciation: Processes that involve hybridization between species

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BIOL 424 Test #3

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