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Biology 2 > Ch.24 > Flashcards

Ch.24 Flashcards

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1
Q

Speciation

A

-formation of new/distinct species in the course of evolution
Origin of new species are a focal point of revolutionary theory
-can occur rapidly/ slowly and can result in a few/many changes in genes
-can occur with/without geographic operation

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2
Q

Macroevolution

A

broad patterns in evolutionary change above species level
-larger changes over a longer period of time
-can result in speciation

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3
Q

Biological species concept

A

-emphasizes reproductive isolation
-characterizes a group as a pop. whose members have the potential to interbreed in nature and produce viable fertile offspring ( don’t successfully breed with other pop.)

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4
Q

Gene flow between pop.

A

holds phenotype of a pop. together

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5
Q

Reproductive isolation

A

-the existence of barriers that impede two species from producing fertile offspring
-prezygotic barriers
-postzygotic barriers

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6
Q

Prezygotic barriers (before)

A

-prevent members of different species from meeting to produce zygote in the first place
-habitat, temporal, behavioral, mechanical, and gametic barriers

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7
Q

Postzygotic barriers (after)

A

reduced hydra viability and fertility, and hybrid breakdown

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8
Q

Imitations of biological species concept

A

-Can’t be applied to fossils or asexual organisms
-emphasizes absence of gene flow

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9
Q

Morphological species concept

A

-Define species by structural features
-applies to sexual and asexual
-relies on subjective criteria
–difficult to determine the degree of difference required for separate species

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10
Q

Ecological species concept

A

-Use a species in terms of its ecological niche
-sexual/asexual
-emphasizes the role of disruptive selection

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11
Q

Phylogenetic species concept

A

-Defines a species of smallest group of individuals on phylogenic tree
-sexual/asexual
-difficult to determine the degree of difference required for separate species

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12
Q

Speciation can occur in 2 ways

A

-allopatric
-sympatric

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13
Q

behavioral isolation

A

Courtship rituals and other behaviors you need to species are effective barriers

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14
Q

allopatric speciation (AS)

A

-“other homeland”
-gene flow is interrupted or reduced when a population is divided into geographically isolated subpopulations
-driven by sexual selection
- in AS, Geographic isolation restrict gene flow between populations

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15
Q

Sympatric speciation

A

“together homeland”
-takes place in geographically overlapping populations
-can result from appearance of new ecological niches
-can result from polyploidy, natural selection, or sexual selection

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16
Q

Definition of a barrier depends on..

A

ability of a pop. to disperse
-ex: canyon may be a barrier for mice but not for birds

17
Q

reproductive isolation

A

-May arise as a result of genetic divergence (evolution caused to be too different to breed), which won’t allow for fertile offspring
-increases as distance between populations increase
-may arise by natural selection, genetic drift, or sexual selection and isolated populations

18
Q

polyploidy

A

Presents an extra set of chromosomes due to accidents during cell division
-more common in plants (crops, cotton, potatoes, tobacco, and wheat)

19
Q

autopolyploid

A

Individual with more than two chrome zone sets derived from one species

20
Q

allopolyploid

A

Species with multiple sets of chromosomes derived from different species sex

21
Q

hybrid zone

A

Region in which members of different species meat and produce hybrids
-can occur in a single band where adjacent species meet

22
Q

Hybrids

A

Results of the meeting between species with incomplete reproductive barriers
-often have reduced fitness

23
Q

3 possible outcomes for hybrid zones

A

-reinforcement
-fusion
-stablilty

24
Q

Reinforcement

A

-strengthening reproductive barriers
-hybrids less fit than parents
-overtime, rate of hybridization decreases
-reproductive barriers are stronger for sympatric than allopatric species

25
Q

Fusion

A

-weakening reproductive barriers
-hybrids are as fit as parents
-if gene flow is enough, parent species confuse into a single species

26
Q

Stability

A

-continued formation of hybrid individuals
-extensive gene flow from outside of hybrid zone can overwhelm selection for increased reproductive isolation inside hybrid zone

27
Q

Punctuated equilibria

A

Corned by Niles Eldredge and Stephan Jay Gould
-described. Apparent stasis punctuated by sudden change

28
Q

microevolution

A

smaller changes over a shorter period of time

Biology 2 (18 decks)

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