Speciation Flashcards

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1
Q

What is the biological species concept?

A

When two groups can reproduce together they are of the same species and their offspring can reproduce

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2
Q

What is speciation?

A

A process by which one species splits into two species.

Segregation of the gene pool of an ancestral species into 2 separate gene pools

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3
Q

What speciation is caused by a geographic barrier?

A

Allopatric speciation

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4
Q

What factors affect allopatric speciation?

A

In different environments, populations will evolve differently through natural selection.

Genetic drift and mutation can also be factors

Most dominant form of speciation

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5
Q

What are the factors that determine the efficacity of a barrier?

A

Size and mobility of the species

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6
Q

What is symmetric speciation?

A

Partition of gene pool happens without physical seperation

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7
Q

What is polyploidy?

A

Duplication of whole sets of chromosomes

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8
Q

How does polyploidy arise?

A
  1. Autopolyploidy
  2. Allopolyploidy
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9
Q

What is autopolyploidy?

A

Chromosome duplication in a single species.

Occurs accidentally if 2 diploid gametes combine resulting in a tetraploid individual

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10
Q

What happens between tetraploid and diploid populations after autopolyploidy?

A

They separate because their hybrid offspring are triploid and sterile

Tetraploid plants can self-fertilize (or mate with another tetraploid), which results in reproductive isolation

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11
Q

What is allopolyploidy?

A

The combining of chromosomes from two different species

This happens when individuals of closely related species interbreed, or hybridize

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12
Q

Why are alloploids usually fertile?

A

Each of the chromosomes has a nearly identical partner to pair with during meiosis

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13
Q

What are prezygotic isolating mechanisms for? What are the types of prezygotic isolating mechanisms?

A

To prevent hybridization from occurring

  • Spatial/Habitat isolation: live in different locations
  • Temporal isolation: Mating periods don’t overlap
  • Behavioral isolation: individuals of one species may reject or fail to recognize individuals of other species as mating partners
  • Mechanical isolation: have differences in size and shape of reproductive organs
  • Gametic isolation: sperm of one species may not attach or penetrate the egg of other species
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14
Q

What are postzygotic isolating mechanisms?

A
  • Hybrid zygote abnormality: fail to mature normally, either dying during development or have severe abnormalities
  • Low hybrid viability: hybrids may survive less well than individuals resulting from matings within populations
  • Hybrid infertility: may mature normally, but be infertile when they attempt to reproduce
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