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Biology - Sabrina > Ch22 speciation > Flashcards

Ch22 speciation Flashcards

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1
Q

speciation 2 parts

A
  1. the process of species formation.
  2. microevolutionary processes that alter the genetic and phenotyppic variation within populations. when these processes differ between populations the populations will diverge genetically and may become so different that we recognize them as different species.
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2
Q

morphological species concept

A

the concept that all individuals of a species share measurable traits that distinguish them from individuals of other species

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3
Q

biological species concept

A

the definition of species based on the ability of populations to interbreed and produce fertile offspring

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4
Q

phylogenetic species concept

A

a concept that seeks to describe species as the smallest group of populations that can be united by shared derived characters

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5
Q

subspecies

A

a taxonomic subdivision of a species

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6
Q

reproductive isolating mechanism

A

a biological characteristic that prevents the gene pools of 2 species from mixing

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7
Q

hybrid

A

an organism produced by mating between parents of different species or subspecies

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8
Q

prezygotic isolating mechanism

A

a reproductive isolating mechanism that acts before the formation of a zygote ( a fertilized egg)

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9
Q

postzygotic isolating mechanism

A

a reproductive isolating mechanism that acts after zygote formation

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10
Q

ecological isolation

A

a prezygotic isolating mechanism in which species live in the same geographical region occupy different habitats

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11
Q

temporal isolation

A

a prezygotic isolating mechanism in which species live in the same habitat but breed at different times of the day or year

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12
Q

behavioral (ethological) isolation

A

a prezygotic isolating mechanism in which 2 species do not mate because of differences in courtship behaviour

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13
Q

mechanical isolation

A

a prezygotic isolating mechanism caused by differences in the structure of reproductive organs or other body parts

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14
Q

Gametic isolation

A

a prezygotic isolating mechanism caused by incompatibility between the sperm of one species and the eggs of another species; may prevent fertilization

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15
Q

Hybrid inviability

A

a postzygotic isolating mechanism in which a hybrid individual has a low probability of survival to the reproductive age

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16
Q

hybrid sterility

A

a postzygotic isolating mechanism in which the hybrid offspring cannot form functional gametes

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17
Q

hybrid breakdown

A

a postzygotic isolating mechanism in which hybrids are capable of reproducing , but their offspring have reduced fertility or reduced valiability

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18
Q

allopatric speciation

A

the evolution of reproductive isolating mechanisms between 2 populations that are geographically separated

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19
Q

species fusion

A

merger of 2 populations into one after the establishment of secondary contact

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20
Q

secondary contact

A

the re-establishment of geographical overlap after a barrier that separated allopatric populations no longer keeps them apart

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21
Q

species cluster

A

a group of closely related species recently descended from a common ancestor

22
Q

hybrid zone

A

a geographical are where the hybrid offspring of 2 divergent species / populations are common

23
Q

reinforcement

A

the enhancement of reproductive isolation that had begun to develop while population were geographically separated

24
Q

sympatric speciation

A

speciation that occurs without the geographical isolation of populations

25
Q

host race

A

a population of insects that may be reproductively isolated from other population of the same species as a consequence of their adaptation to feed on a specific host plant species

26
Q

polyploidy

A

(POLY was HAPpy with her Car)

the genetic condition of having one/more extra copies of the entire haploid complement of chromosomes

27
Q

autopolyploidy

A

(PARENTS gave Carmen a Automobile)

the genetic condition of having more than 2 sets of chromosomes from the same parent species

28
Q

unreduced gamete

A

a gamete that contains the same number of chromosomes as a somatic cell (46)

29
Q

allopolypoidy

A

(Allo for Apart)

the genetic condition of having 2 or more complete sets of chromosomes from different parent species

30
Q

ring species

A

a species with a geographical distribution that forms a ring around uninhabitable terrain

31
Q

cline

A

a pattern of smooth variation in a characteristic along a geographical gradient

32
Q

2 advantages of the morphological species concept

A
  1. practical way to identify species

2. can be applies to extincted fossilized organisms

33
Q

3 disadvantages of the morphological species concept

A
  1. tells us little about the evolutionary processes that produced new species
  2. morphology doesn’t help distinguish some closely related species that are nearly identical in appearance
  3. difficult to apply morphology to variable species. if a species has polymorphism for example, then the phenotypic variation may lead the organisms being identified as different species (e.g European garden snails)
34
Q

the biological species concept in Mayr’s words

A

“groups of interbreeding natural population that are reproductively isolated from (do not produce fertile offspring with) other such groups”

35
Q

the biological species concept emphasizes 3 things

A
  1. the genetic cohesiveness of species
    - same species experience gene flow
    - species=large gene pool
  2. genetic distinctive of each species
    - different species=reproductively isolated, so cannot exchange genetic info
  3. individuals of a species generally look a like
    - same gene pool
36
Q

3 advantages of the biological species concept

A
  1. species defined on basis of evolutionary concepts
  2. species=relatively easily to identify
  3. clear indication of process
37
Q

2 disadvantages of the biological species concept

A
  1. doesnt work for life that reproduce sexually (e.g most bacteria)
  2. doesnt work for extincted life forms
38
Q

phylogenetic species comprises population that share a ……

A

recent evolutionary history

39
Q

3 advantages of the phylogenetic species concept

A
  1. can be applied to any organism (sexual and asexual)
  2. can be applied to extinct organisms
  3. distinctiveness of branches reflects lack of gene flow
40
Q

2 disadvantages of the phylogenetic species concept

A
  1. evolutionary history of very few groups of organisms are known
  2. level of genetic distinctiveness used to define species is arbitrary (e.g. 70% similar are they a related species or not?)
41
Q

many species exhibit substantial geographical variation…2 patterns

A
  1. ring species

2. clinal variation

42
Q

5 types of prezygotic mechanisms

A
  1. ecological
  2. temporal
  3. behavioural
  4. mechanical
  5. gamete
43
Q

3 postzygotic mechanisms

A
  1. hybrid inviability
  2. hybrid sterility
  3. hybrid breakdown
44
Q

3 modes of speciation based on the geographical relationships as they become reproductively isolated

A
  1. allopatric speciation
  2. parapatric speciation
  3. sympatric speciation
45
Q

allopatric speciation occurs in 2 stages

A
  1. population become geographically separated by a physical barrier
  2. population accumulate genetic differences that isolate them reproductively
    - genetic drift= founder effect
    - natural selection
    - populations experience distinct mutations
46
Q

secondary contact in allopatric speciation is when…..

A

barrier =eliminated or breached

47
Q

secondary contact tests whether

A

populations have diverge enough to make them reproductively isolated. if the gene pools didnt differentiate much then species fusion will occur

48
Q

4 properties of parapatric speciation

A
  1. speciation arising between adjacent populations
  2. may occur if hybrids have low relative fitness
  3. individuals colonise neighbouring habitat
  4. different genetic variants= favoured in each habitat
49
Q

3 genetic mechanisms can lead to reproductive isolation

A
  1. genetic divergence between allopatric populations
  2. polyploidy in sympatric populations
  3. chromosome alterations
50
Q

insects that feed on one/more plant species are likely to evolve by sympatric speciation forming…..

A

host races

51
Q

genetic divergence in allopatric populations can lead to speciation in 3 processes

A
  1. postzygotic isolation accidental byproduct of …absence of gene flow accumulate genetic difference from: mutation, genetic drift and natural selection
  2. selection cannot promote isolating mechanisms directly in allopatry
  3. during secondary contact - reinforcement
52
Q

polyploid individuals arise from 2 things

A
  1. autopolyloidy

2. allopolyploidy

Biology - Sabrina (9 decks)

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