CH24 Flashcards

1
Q

Define

Speciation

A

Process by which one species splits into two or more species. It is responsible for the tremendous biodiversity observable and links microevolution to macroevolution

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2
Q

Define

Macroevolution

A

Broad pattern of evolution above the species level

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3
Q

Define

Biological species concept

A

Species are differentiated by their ability to interbreed and produce fertile, viable offspring

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4
Q

Define

Morphological species concept

A

Species differentiated by body shape and features (subjective but works for asexual species)

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5
Q

Define

Ecological species concept

A

Species differentiated by how species interact with their environment

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6
Q

Define

Phylogenetic species concept

A

Species defined by the smallest group of individuals that share a common ancestor

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7
Q

Define

Reproductive isolation

A

Biological factors that prevents members of 2 different species from interbreeding and producing fertile + viable offspring

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8
Q

What are the prezygotic barriers?

A
  1. Habitat isolation
  2. Temporal isolation
  3. Behavioural isolation
  4. Mechanical isolation
  5. Gametic isolation
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9
Q

What are the postzygotic barriers?

A
  1. Reduced Hybrid Viability
  2. Reduced Hybrid Fertility
  3. Hybrid breakdown (above problems occur for hybrid-hybrid offspring)
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10
Q

Define

Allopatric speciation

A

Interruption of gene flow by geographical isolation. Groups are separated and gene pools may diverge, which leads to reproductive barriers

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11
Q

Define

Sympatric speciation

A

Interruption of gene flow despite lack of physical separation

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12
Q

What are some ways by which sympatric speciation occurs?

A
  • Polyploidy (mutation-driven speciation)
  • Habitat differentiation (subset of population exploits a habitat or diurnal/nocturnal cyclles)
  • Non-random mating (ex: mosquitofish choosing mates with similar body shape)
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13
Q

What are the forms of polyploidy?

A
  • Autopolyploidy: species just doubles its number of chromosomes, either autopollinate or mate with others 2ns
  • Allopolyploidy: Infertile hybrid offspring that can propagate asexually (ex: 2n=6 and 2n=4) come together, create a 5 chromosome infertile offspring)
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14
Q

Define

Hybrid zone

A

Region in which members of different species meet and mate, producing some offspring of mixed ancestry (intermediate mediocre phenotype)

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15
Q

What are the possibilities for a hybrid zone (what can become of it)?

A
  • Reinforcement: hybrids are less fit than parents, natural selections strengthens prezygotic barriers
  • Fusion: reproductive barriers weaken/vanish, fusion of species
  • Stability: continuous production of hybrids, happens in narrow hybrid zones
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16
Q

What are the ways in which species fall and rise?

A
  • Plate Tectonics
  • Mass Extinctions
  • Adaptive Radiations
17
Q

Define

Plate tectonics

A
  • Continents float on mantle in a movement called continental drift
  • Their collision causes the creation of mountains, islands (promotes geographical separation)
18
Q

What were the biggest events of mass extinction?

A

Permian Extinction and Cretaceous Extinction

19
Q

Describe

Permian Extinction

A

Permian Extinction: 250 mya for 500k years. Extreme volcanic activity, acid oceans, anoxia, global warming and formation of Pangea. Loss of 95% marine life and 70% terrestrial.

20
Q

Describe

Cretaceous Extinction

A

Cretaceous Extinction: 65 mya, few k years. Asteroid collides with earth, volcanic activity, huge cloud of debris. Loss of dinosaurs and 50% marine life.

21
Q

Describe

Adaptive radiations

A
  • Rapid speciation and diversification
  • Organisms will out vacant areas/niches otherwise occupied by other species
  • Regional: face little competition after migrating to a new location
    ex: Mammals adaptively radiated after Cretaceous Extinction