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HELENP EE Evolution and Natural Selection > EE Lecture 11: Species and Speciation > Flashcards

EE Lecture 11: Species and Speciation Flashcards

1
Q

why do species matter

A

theyre fundamental unit of biodiversity important in terms of evoln, ecology,conservation

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2
Q

what are main types of definitions for species

A
  1. morphological species concept
  2. biological species concept
  3. phylogenetic species concept
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3
Q

what is the morphological species concept

A

species are a collection of individuals with a similar morphology that differ from other such groups

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4
Q

what species concept is one that states species are a collection of individuals with similar morphological traits that differ from other groups

A

morphological species concept

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5
Q

what is the biological species concept

A

species are a collection of individuals that can interbreed to produce fertile offspring and there is reproductive isolation from other species

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6
Q

what species concept is one that states species are a collection of individuals that can interbreed to produce fertile offspring

A

biological species concept

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7
Q

what is the phylogenetic species concept

A

species are a distinct group that share a common ancestor and can be distinguished from other such groups

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8
Q

give an example of a species that cant be categorized/ defined by any of the species concepts

A

Conodonts ~380MYA

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9
Q

why cant the Conodonts be defined by any species concepts

A

not all parts of body fossilise - only apatin mouthparts
theyre extinct - only known from their fossil record
have no known close relatives

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10
Q

give pros of morphological species concept

A

easy

adaptive traits

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11
Q

give cons of morphological species concept

A

plasticity in species - polymorphism
eg. worms in hydrothermal vents
cryptic species
purely descriptive therefore subjective

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12
Q

give an example of a species that defies the morphological species concept (plasticity terns)

A

hydrothermal vent worms show plasticity within the same species
HOT vents: short, fat, flexible white tubes
COLD DIFFUSE VENT: long skinny
initially described as 2 Ridgeia species, but now names R.piscesea

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13
Q

describe classification of Ridgeia piscesae species

A

they show plasticity dependent on which hydrothermal vent they live in
worms in hot vents are fat and short - flexible white tunes
worms in cold vents are long and skinny
they were initially described as 2 separate species, but now 1

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14
Q

give an example of a species that defies the morphological species concept (due to cryptic)

A

limpets in deep sea trenches - deep ocean exploration

multiple species with one formn

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15
Q

what are cryptic species

give example

A

one of two or more morphologically indistinguishable biological groups that are incapable of interbreeding
eg. lepetodrilid limpets in deep sea trenches
vesicomyid clams

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16
Q

what pros of biological species concept

A

key evolnary concept for sexuals

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17
Q

cons of biological species concept

A

asexuals
hybrids/ring species
hard to use in practise as need crossing experiments

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18
Q

give an example of species that defy the biological species concept

A

blue whale and fin whale two different species but can interbereed to bproduce a hybrid

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19
Q

outline differences between blue whale and fin whale

A

blue whale: darke baleen plates, large dlippers

fin whale: short snout, dark back&flanks

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20
Q

give an example of a ring species

A

Ensantina salamanders in California

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21
Q

what is a ring species

A

different species arrange themselves in a circle within their own territories, the ones directly next to eachother CAN interbreed however the ones not directly next door neighbours cant interbreed

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22
Q

which species concept is defied by ring species

A

biological species concept

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23
Q

what are the pros of the biological species concept

A

practical guide to delimitation, still based on evolnary concept and applies to asexuals

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24
Q

cons of phylogenetic species concept

A

cryptic species
taxonomic inflation - where known subspecies are raised to species as a result of a change in species concept rather than new discovery

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25
Q

what is taxonomic inflation

A

where known subspecies are raised to species due to a new description of species concept as opposed to new species discovery

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26
Q

how has taxonomic inflation affected primates

A

nearly double, mostly subspecies raised to spcies by phylogenetic species concept

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27
Q

what is speciation

A

single ancestral pop splits into two genetically distinct daughter pops

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28
Q

what causes speciation

A
  1. isolation

2. divergent selection

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29
Q

what is isolation

A

something that stops interbreeding between 2 parts of the ancestral pop
eg. geographic barrier to migration

30
Q

what is a geographic barrier to migration causing

A

reproductive isolation

31
Q

name examples of geographical barriers to migration

A

river
mountain range
habitat fragmentation

32
Q

what is divergent selection

A

accumulation of differences between groups which can lead to the formation of new species, usually a result of diffusion of the same species to different and isolated environments which blocks the gene flow among the distinct populations allowing differentiated fixation of characteristics

33
Q

what is the accumulation of different traits between groups which can elad to the formation of a new species called
give example

A

divergent selection
eg. trait: beak size in finches
one for seeds one for insects

34
Q

how can you test ideas about speciation

A
  1. experiments: artificial selection
  2. fossil record tracking
  3. genetic crosses
  4. phylogenies
35
Q

what is allopatric speciation

A

geographic speciation occxurs when biological pops of same species become isolated
eg. marine life seperated by emergence of Isthmus of Panama ~3MYA - lots of sister species pairs - One Carribean and one PAcific

36
Q

what speciation is caused when pops of same species become isolated by a reproductive barrier

A

allopatric speciation

37
Q

give an example of allopatric isolation

A

species pairs when marine life separated by emergence of Isthmus of Panama ~3MYA

38
Q

when did emergence of Isthmus of Panama occur

what is its significance

A

~3MYA

significant because it separated marine life, so now lots of sister species pairs - One Caribbean and One Pacific

39
Q

what do sister species on opposite sides of the Isthmus show

A

allopatric speciation

  1. Reproductive ISolation: mainly behavioural eg.mate choice
  2. GEnetic Divergence based on mtDNA
  3. Morphological Divergence``
40
Q

give genotypes of geographical isolation: allopatric speciation

A

AABB -> aaBB and AAbb

41
Q

what happens if 2 popns separated by allopatric speciation reestablish contact

A
  1. RI has already evolved (prezygotic or postzygotic) so coexist as separate species
  2. Interbreed - hybridise and remain one species
  3. Partial isolation: selection against production of inviable hybrids leads to reinforcement of prezygotic isolation - mating preferences diverge and they coexist as separate species
42
Q

what is ecological speciation

A

genetic divergence of pops driven by adaptation to the different (a)biotic enviros

43
Q

give an example of ecological divergence

A

Galapagos finches
different enviros on different islands = different available foods
trophic specialisation = song differences, female preferences = RI

44
Q

in terms of divergent selection and geographic isolation, where is ecological divergence

A

STRONG divergent selection but GEOGRAPHIC isolation @ ANY level

45
Q

in terms of divergent selection and geographic isolation, where is allopatric speciation

A

HIGH geographic isolation and ANY divergent selection (weak to strong)

46
Q

which divergence is caused from STRONG divergent selection and any geographical isolation

A

ECOLOGICAL speciation

47
Q

which divergence is caused from HIGH geographical isolation and any (weak or strong) divergent selection

A

ALLOPATRIC speciation

48
Q

what is parapatric divergence

A

extremely rare
occurs when pops are separated by an extreme change in habitat as opposed to geographical barrier
eg, mimulus copper waste

49
Q

common on commonness of parapatric divergence

A

extremely rare

50
Q

give an example of parapatric divergence

A

Mimulus on copper waste
M.guttatus is widespread - adj. pops on copper mine waste have evolved copper tolerance - partial gene flow, strong selection - reproductive isolatoin:hybrid lethality
there was a locus that appeared to cause copper tolerance and hybrid lethality

51
Q

in terms of divergent selection and geographic isolation,what is parapatric divergence

A

strong divergent selection and medium geographical isolation

52
Q

what type of divergence does Mimulus guttatus show

A

parapatric divergence

53
Q

what type of divergence does Sinningia show

A

parapatric divergence along altitudinal gradient

S. cochlearis @ high altitudes and S.gigantifolia at low altitudes

54
Q

how does ecological divergence speed up origin of reproductive isolation

A
  1. selection against intermediate hybrids reinforces prezygotic isolation eg. flower type,pollinators
  2. RI evolves as pleiotropic (by product of ecological divergence)
55
Q

what is prezygotic reproductive isolation

A

mate choice

genital morphology

56
Q

what is postzygotic reproductive isolation

A

hybrids inviable
sterile
poorly adaptive

57
Q

what is sympatric speciation

A

process through which new species evolve from a single ancestral species while inhabiting the same geographic region

58
Q

in terms of divergent selection and geographic isolation, what is sympatric speciation

A

low geographic isolation and strong divergent selection

59
Q

in sympatric speciation, where geographic isolation is low, how does reproductive isolation originate in a popn

A

originates solely as a result of divergent selection

60
Q

give an example of a form of sympatric isolation

A

host-shift speciation

61
Q

what is host shift speciation a form of

A

sympatric speciation

62
Q

what is host shift speciation

A

a form of sympatric speciation whereby parasite or plant-feeding insect specialised on host, few individuals shift to new host, if mating occurs within host or on natal plant, automatically leads to isolation (micro-allopatry)
adaptations to new condns drives further divergence

63
Q

give an example of host-shift speciation

A

host race formation in maggot flies :Rhaglottis

64
Q

what is host race formation in maggot flies Rhagoletis an example of

A

host shift speciation

65
Q

what is microallopatry

A

occurs in host shift speciation where if mating occurs within host or on natal plant, automatically leads to isolation

66
Q

discuss the host shift speciation in apple maggot fly : R.pomonella

A

Host shift from hawthorn to apple
adults mate on native fruit therefore inherent isolation
then divergent selection betwen hosts: apple fruit is easier than haw, hybrids maladapted to both habitas
genetic divergence between host races created allozymes

67
Q

what is the controversy over sympatric speciation

A

its hard to show that two sister species actually formed in sympatry, present day sympatry could be secondary contact
host shifts could occur in allopatry
different races could have involved immigration from other areas eg.MExico

68
Q

what are the main conclusions of ecological speciation

A

lots of evidence that ecological divergence drives speciation
sympatric speciation is rare

69
Q

what are the best condns for speciation

A

strong divergent selection with some geographic isolation

70
Q

what effect can a major genome change have

A

major genome change can spontaneously create reproductive isolation and ecological differences

71
Q

give an example of a major genome change causing speciation

A

Louisiana irisis - created a hybrid swarm

72
Q

what does hybridisation produce

A

ecological novelty as well as reproductive isolation

HELENP EE Evolution and Natural Selection (14 decks)

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