Biology Chapter on Speciation and Species Concepts
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Questions and Answers

What is the primary characteristic of ecological speciation?

  • It results only from genetic mutations.
  • It leads to hybrid vigor.
  • It involves reproductive isolation as a by-product of adaptation. (correct)
  • It requires geographical isolation.

Which of the following statements about polyploidization is true?

  • It increases the number of chromosomes from the same species. (correct)
  • It results in the complete failure of fertilization.
  • It can instantly create reproductive isolation.
  • It only occurs in animal species.

What does reinforcement in the context of speciation refer to?

  • The strengthening of postzygotic barriers only.
  • The enhancement of prezygotic barriers by natural selection. (correct)
  • The promotion of hybrid formation.
  • The weakening of species boundaries.

How is speciation studied experimentally in a laboratory setting?

<p>By testing various mechanisms and conditions affecting speciation. (D)</p> Signup and view all the answers

What is expected from ecological speciation regarding postzygotic isolation?

<p>It predicts reduced hybrid fitness in the absence of intermediate environments. (D)</p> Signup and view all the answers

What is the main characteristic that defines speciation?

<p>Splitting of a species into two or more distinct species (C)</p> Signup and view all the answers

Which species concept is focused on reproductive compatibility?

<p>Biological Species Concept (A)</p> Signup and view all the answers

What type of reproductive barrier occurs before mating?

<p>Temporal isolation (A)</p> Signup and view all the answers

What disadvantage does the Biological Species Concept face?

<p>It is complex to test reproductive barriers. (D)</p> Signup and view all the answers

Under what conditions does sympatric speciation typically occur?

<p>In the presence of strong disruptive selection (C)</p> Signup and view all the answers

Which of the following is NOT a prezygotic reproductive barrier?

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

What best describes allopatric speciation?

<p>Speciation resulting from geographical barriers interrupting gene flow (A)</p> Signup and view all the answers

Which statement about postzygotic reproductive barriers is true?

<p>They result in reduced viability or fertility of hybrid offspring. (D)</p> Signup and view all the answers

What does the biological species concept define species as?

<p>Groups that interbreed and produce fertile offspring in nature. (A)</p> Signup and view all the answers

Natural selection can maintain divergence despite gene flow.

<p>True (A)</p> Signup and view all the answers

Which of these is NOT a prezygotic barrier?

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

What process can lead to speciation in the absence of a geographic barrier?

<p>Sympatric speciation</p> Signup and view all the answers

Which type of polyploidy involves the doubling of chromosomes within a single species?

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

What does the term 'reinforcement' refer to in the context of speciation?

<p>The strengthening of prezygotic barriers by natural selection.</p> Signup and view all the answers

Which of these is NOT a common technique used in the study of speciation?

<p>Astrophysical observation (B)</p> Signup and view all the answers

Ecological speciation can be tested by comparing the degree of behavioral isolation between populations in different environments.

<p>True (A)</p> Signup and view all the answers

What is the primary method of testing for ecologically-dependent postzygotic isolation?

<p>Reciprocal transplantation (B)</p> Signup and view all the answers

Cladistics is an approach to systematics that uses homologies to define clades.

<p>True (A)</p> Signup and view all the answers

What type of group comprises an ancestral species and ALL of its descendants?

<p>Monophyletic group</p> Signup and view all the answers

What type of character is unique to a group and shared by all members due to descent from a common ancestor?

<p>Derived character (B)</p> Signup and view all the answers

Analogous traits, which are similar due to convergent evolution, are highly useful in constructing accurate phylogenies.

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

What principle states that the most likely phylogenetic tree is the one that involves the fewest number of evolutionary transitions?

<p>The principle of parsimony</p> Signup and view all the answers

What do cladograms depict?

<p>Branching patterns only (A)</p> Signup and view all the answers

What is the primary method of dating branching points (nodes) on a phylogeny?

<p>Molecular clock analysis</p> Signup and view all the answers

What does the molecular clock assume about the rate of nucleotide substitutions?

<p>It's constant for a given gene (C)</p> Signup and view all the answers

Flashcards

Sympatric Speciation

Speciation that occurs within the same geographic area, as opposed to allopatric speciation which occurs in different areas.

Ecological Speciation

Reproductive isolation arises from adaptation to different ecological niches within a shared habitat.

Polyploidization

A speciation mechanism where a species gains an extra set of chromosomes, often leading to instant reproductive isolation.

Autopolyploid

A type of polyploidization where a species gains an extra set of chromosomes from its own species.

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Allopolyploid

A type of polyploidization where a species gains an extra set of chromosomes from a different species.

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Speciation

The process where one species splits into two or more species.

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Biological Species Concept

Groups that can naturally interbreed and produce fertile offspring are considered the same species.

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Reproductive Barriers

Biological factors that reduce or prevent gene flow between species.

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Allopatric Speciation

Speciation that occurs when populations are geographically separated.

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Prezygotic Barrier

Reproductive barriers that occur before the formation of a zygote.

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Postzygotic Barrier

Reproductive barriers that occur after the formation of a hybrid zygote.

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Systematics Definition

The science of classifying organisms and determining their evolutionary relationships.

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Taxonomy

The branch of systematics focused on naming and classifying organisms.

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Phylogenetics

The study of evolutionary relationships among organisms.

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Phylogenetic Tree

A diagrammatic hypothesis of the evolutionary relationships of a group of organisms based on a phylogenetic analysis.

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Carl Linnaeus

Developed the hierarchical system for classifying organisms, known as the Linnaean system.

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Linnaean System

A hierarchical system of classifying organisms based on shared characteristics.

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Taxon

A group at any level of the classification hierarchy (e.g., species, genera, families, etc.)

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Binomial Nomenclature

A two-part naming system for species, using genus and species names (e.g., Homo sapiens).

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Homologous Traits

Similarities in organisms due to shared ancestry.

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Analogous Traits

Similarities in organisms not due to shared ancestry but to shared environment or independent mutations.

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Cladistics

An approach to systematics that uses shared evolutionary history as the primary basis for classification.

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Clade

A monophyletic group, including an ancestral species and all its descendants.

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Monophyletic Group

A group that includes a common ancestor and all of its descendants.

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Paraphyletic Group

A group containing an ancestor and only some of its descendants, not all.

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Polyphyletic Group

A group lacking a common ancestor for all its members, not reflecting evolutionary history accurately.

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Shared Derived Characters

Characters unique to a group, inherited from a common ancestor.

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Ancestral Character

A character present in both the group of interest and its ancestor.

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Outgroup

A species outside the group of interest (ingroup) used for comparison in phylogenetic analysis.

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Convergent Evolution

Independent evolution of similar traits in different lineages.

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Principle of Parsimony

The most likely phylogenetic tree is the one requiring the fewest evolutionary changes.

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Cladogram

A phylogenetic tree showing only branching patterns, without information on timing or amount of change.

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Phylogram

A phylogenetic tree showing branching patterns and branch lengths proportional to genetic change or time.

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Molecular Clock

A method for estimating the time of evolutionary events based on the rate of molecular changes.

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Fossil Record

The preserved remains or traces of organisms from the past.

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Radiometric Dating

A technique for determining the age of materials by measuring the decay of radioactive isotopes.

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Stratigraphy

The study of layered rocks (strata) and their sequence.

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Extinct Species

Species that no longer exist.

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Extant Species

Species that are currently living.

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L.U.C.A.

Last Universal Common Ancestor, the common ancestor of all living organisms.

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Study Notes

Speciation & Species Concepts

  • Speciation is the process where a species splits into two or more species
  • Daughter species share characteristics with a common ancestor
  • Irreversible endpoint; two species cannot form fertile hybrids

Species Concepts

  • Biological species concept (BSC): Groups that interbreed and produce fertile offspring in nature. Same species if reproductively compatible, different species if reproductively isolated
  • Morphological similarity: species are similar in appearance, but misses cryptic species
  • Ecological niche: species occupy different niches. Requires conditions to apply to fossils; subjective

Reproductive Barriers

  • Prezygotic barriers occur before mating
    • Habitat isolation
    • Temporal isolation
    • Behavioral/pollinator isolation
    • Mechanical isolation
    • Gametic isolation (including sperm competition & preference)
  • Postzygotic barriers occur after mating
    • Genetic incompatibilities: gene interaction reduces viability/fertility of offspring
    • Ecologically-dependent isolation: reduction in hybrid fitness due to phenotype/environment mismatch between parents

Mechanisms of Speciation

  • Allopatric speciation: geographic isolation (gene flow interrupted); populations evolve independently and accumulate reproductive barriers (e.g., different mating calls).

  • Sympatric speciation: speciation in the same geographic area; hard to overcome unrestricted gene flow. Can occur from:

    • Polyploidization (increase in chromosome sets, creating instant postzygotic isolation)
    • Disruptive selection (strong selection for traits, leading to assorative mating) and positive assortive mating

  • Ecological speciation: reproductive isolation arises as a by-product of adaptation to different environments. Selection for diverging traits leads to reproductive isolation regardless of geographical barriers

  • Reinforcement: strengthening of prezygotic barriers, often post-initiation of speciation, in sympatry leads to stronger prezygotic isolation (e.g., selection for different mating calls)

  • Polyploidization: increase in chromosome sets; postzygotic isolation can be instant; common in flowering plants, two types:

    • Autopolyploid: chromosomes from a single species
    • Allopolyploid: chromosomes from two or more different species

Studying Speciation

  • Laboratory studies: testing feasibility of various speciation mechanisms; exploring conditions for speciation to occur.
  • Experimental evolution: multiple populations derived from a common ancestor, evolution tracked under controlled conditions; useful for verifying mechanisms of divergence.
  • Ecological speciation: predicts stronger behavioural isolation between different-environment populations.

Speciation in Nature

  • Postzygotic isolation: hybrid fitness is reduced; occurs in the absence of intermediate environments; occurs when ecological speciation is expected.
  • Tested via reciprocal transplant of parental species and hybrids in both habitats

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Related Documents

Speciation & Species Concepts PDF
Systematics: Definitions & Phylogenetic Trees PDF

Description

Explore the processes of speciation and the various species concepts in this quiz. Delve into reproductive barriers, both prezygotic and postzygotic, and how they contribute to the formation of new species. Test your understanding of biological, morphological, and ecological classifications.

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