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BIO3A: Processes 2 Patterns > S2: W7 (Dr. Hanlie) > Flashcards

S2: W7 (Dr. Hanlie) Flashcards

1
Q

Galapagos islands?

A

= a “hotbed” of speciation.

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2
Q

Why are the Galapagos islands a “hotbed” of speciation?

A

It’s because the islands arose from volcanic islands.

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3
Q

Speciation?

A

= process by which new species are formed.

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4
Q

Speciation = …?

A

Cladogenesis.

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5
Q

Modes of speciation? (3)

A

• Allopatric speciation.
• Parapatric speciation.
• Sympatric speciation.

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6
Q

“Patric”?

A

= place.

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7
Q

Allopatric speciation process? (4)

A

• Original population.
|
• Barrier formed.
|
• Populations in isolation.
|
• New distinct species after equilibrium.

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8
Q

Parapatric speciation process? (4)

A

• Original population.
|
• New niche entered.
|
• In new niche.
|
• New distinct species after equilibrium.

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9
Q

Sympatric speciation process? (4)

A

• Original population.
|
• Polymorphism.
|
• Within the population.
|
• New distinct species after equilibrium.

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10
Q

Types of speciation in general? (2)

A

• Allopatric speciation.
• Non-allopatric speciation.

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11
Q

Types of allopatric speciation? (2)

A

• Allopatric speciation by vicariance/Vicariant speciation.
• Peripatric speciation.

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12
Q

Types of Non-allopatric speciation? (2)

A

• Parapatric speciation.
• Sympatric speciation.

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13
Q

What causes speciation to occur?

A
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14
Q

What can happen if drivers disappear?

A

Hybridization (uncommon).

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15
Q

Vicariant speciation?

A

= geographic isolation due to a barrier to dispersal & gene flow.

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16
Q

Egs of barriers? (4)

A

• Uplifting of mountains.
• Continental drift.
• Changes in the flow of rivers.
• Changes in environment (desertification).

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17
Q

Eg of Vicariant speciation?

A

Panamic porkfish & Porkfish.

• the former lives in the Pacific ocean & the latter lives in the Atlantic ocean.

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18
Q

Peripatric speciation?

A

= small, isolated population, usually on the periphery of a larger ancestral species gives rise to a distinct species (founder effect).

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19
Q

Peripatric speciation attributes? (2)

A

• Active dispersal into an area not previously occupied.
• Periphery is isolated.

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20
Q

Egs of Peripatric speciation? (2)

A

• Hawaiian picture-winged Drosophila.
• Mexican prairie dog.

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21
Q

Egs of Peripatric speciation? (2)

A

• Hawaiian picture-winged Drosophila.
• Mexican prairie dog.

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22
Q

Explain Hawaiian picture-winged Drosophila?

A

12 species arose from a single species that migrated from the mainland.

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23
Q

Explain Hawaiian picture-winged Drosophila?

A

12 species arose from a single species that migrated from the mainland.

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24
Q

Explain Mexican prairie dog? (5)

A

• Grassland ecosystems.
• Shifts in distribution related to Pleistocene climate change.
• Divergence from C. ludonicianus.
• Climate change promoted biogeographical substructure within Chihuahua descent.
• Population expansion resulted in secondary co tact between lineages of C. ludovicianus.

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25
Q

What happens if separated populations come into contact after removal of barrier? (3)

A

• If reproductively isolated, no mating/no viable offspring.

• If not completely reproductively isolated, may form secondary hybrid zone where hybrids are sterile/inviable/less fit.

• Reinforcement of NS.

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26
Q

What happens if separated populations come into contact after removal of barrier if reproductively isolated (prezygotic/postzygotic)?

A

No mating/no viable offspring.

27
Q

What happens if separated populations come into contact after removal of barrier if not completely reproductively isolated? (2)

A

• May form secondary hybrid zone.
• Hybrids sterile/inviable/less fit.

28
Q

Hybrids sterile/inviable/less fit attributes? (2)

A

• Lower rates of survival.
• Eg due to epistatic incompatibility.

29
Q

Eg of What happens if separated populations come into contact after removal of barrier?

A

Green-eyed tree frog.

30
Q

Explain Green-eyed tree frog? (3)

A

• Habitat isolation.
• Event = deforestation (remove trees for agricultural areas).
• Evolved 2 different mating calls due to different habitat structure.

31
Q

Non-allopatric speciation?

A

= speciation is initiated when there’s incomplete geographic separation of two or more populations of an ancestral species.

32
Q

Non-allopatric speciation attribute?

A

Limited gene flow continues to occur between populations, yet there is divergence.

33
Q

Parapatric speciation?

A

= populations occur in adjacent regions with different selection pressures (eg in an ecological cline) or where 2 different habitats meet.

34
Q

Parapatric speciation attributes? (2)

A

• Gene flow occurs bit “hybrid”.
• Especially if drivers are weak, we can have a zone of hybridization or secondary contact (ecological niche).

35
Q

Egs of Parapatric speciation? (3)

A

• Grasses in the vicinity of mines.
• Orchid Satyrium hallackii.
• Carrion crow & hooded crow.

36
Q

Explain eg 1 of Parapatric speciation? (2)

A

• Have diverged from neighbouring populations in:
- tolerance to heavy metals.
- flowering time.
- self pollinate more frequently.

• Eurasia (uncontaminated) & Northern Africa (mine waste).

37
Q

Explain eg 2 of Parapatric speciation? (4)

A

• Separation by pollinator shift along ecological gradient.
• Different pollinators.
• One hawkmoth & other carpenter bee.
• Proboscis vs spur length.

38
Q

Explain eg 3 of Parapatric speciation? (2)

A

• The 2 species of crow meet.
• There’s a primary hybrid zone.

39
Q

Sympatric speciation?

A

= occurs when one or more new species arise without geographical segregation of populations.

40
Q

Sympatric speciation attributes? (6)

A

• Models postulate disruptive selection (eg in 2 microhabitats), which leads to Intermediate phenotypes (heterozygotes) that have low fitness.

• May involve one or many loci.

• Difficult to prove.

• Occupy different microhabitats which leads to Intermediate phenotypes that have lower fitness.

• Genetic differences result in reproductive isolation.

• Should also be linked to mate selection.

41
Q

Eg of Sympatric speciation?

A

Apple maggot fly.

42
Q

Explain eg of Sympatric speciation? (5)

A

• Lay eggs on Hawthorn fruit.
• Moved onto apples (shifted host).
• Speciated sympatrically.
• From Hawthorn to apples.
• Timing of fruit mating differs.

43
Q

What do we use to hypothesize modes of speciation? (3)

A

• Distribution maps.
• Habitat & body size information.
• Phylogenies.

44
Q

Drivers of speciation? (6)

A

• Barrier.
• Geographical distance.
• Ecological.
• Reproduction.
• Genetic isolation (no gene flow).
• Divergences (NS/SS).

45
Q

Eg of where a competitor caused character displacement in a sympatric population?

A

Geospiza fortis & G. magnirostris.

46
Q

Character?

A

= useful features that help species to exploit resources.

47
Q

Types of character divergence? (2)

A

• Character displacement.
• Character release.

48
Q

Character displacement attributes? (5)

A

• Due to competition.
• Control.
• Character gets displaced.
• Evolutionary divergence in resource-exploiting traits.
• Caused by interspecific competition.

49
Q

Chatacter release attributes? (3)

A

• No competition.
• No control.
• Takes advantage of variety of resources in the absence of competition.

50
Q

Driver of something?

A

= what is the underlying cause behind a certain geographical speciation pattern.

51
Q

General process in terms of character divergence types? (4)

A

Character release
|
Drought/event happens
|
Competitor introduced
|
Character displacement

52
Q

Eg of character divergence types?

A

Geospiza fortis (medium ground finch).

53
Q

Explain eg of character divergence types? (6)

A

• Daphne major.
• Absence of small ground finch.
• Medium ground finch.
• Presence of new competitor (large ground finch).
• Same species, different beak size.

• Process:
Character release
|
Drought happened (“killed” small beak variant)
|
Competitor introduced.
|
Character displacement (evolved a medium sized beak to “widen diet”).

54
Q

Explain Cactus finches? (7)

A

● Eg of Sympatric speciation.

● Males singing song type A had longer, wider beaks & ate cactus seeds in fruit. Males singing song type B had smaller, narrower beaks & ate insect larvae in cactus pads.

● Divergent selection.

● No two males with the same song type.

● Enforced by continuous climatic changes.

● No assortative mating by females.

● Territorial pattern disappears in wetter year (secondary pattern):
• beak size is now intermediate.
• songs are no longer different.

55
Q

Cactus finches paper?

A

Grant & Grant, 1983.

56
Q

Conclusion of Cactus finches? (2)

A

● Mate choice is not genetically correlated with the use of a particular niche.

● Drivers were weak & didn’t prevent genre flow.

57
Q

Explain Warbler finch? (4)

A

● Ecological adaptation in parapatry (song differences).

● Secondary contact phase (very little discrimination of heterospecific song).

● Two morphologically similar species.

● Occupy similar ecological niches.

58
Q

Warbler finch paper?

A

Grant & Grant, 2006.

59
Q

Explain Grey warbler finch & Green warbler finch? (4)

A

● Low levels of genetic divergence/genetic distance.

● Positive correlation between genetic distance & differences in maximum elevation (ecological differentiation ).

● Females have chosen to breed on islands with habitats similar to where they were born.

● Phylogram of mtDNA haplotypes & geographical location.

60
Q

Grey & Green warbler finch paper?

A

Tonnis et al., 2005.

61
Q

Grey & Green warbler finch conclusion? (2)

A

● Genetic relatedness among populations is associated with habitat similarity.

● Habitat choice explains genetic & habitat similarities.

62
Q

Explain Disa draconis complex species? (6)

A

● Habitat isolation (2 adjacent in Western Cape).

● Horse fly (mountain form) with short spur length.

● Long-tongued fly (sandplain form) with long spur length.

● Orchid species have different spur length (evolve/diverge as such).

● If a short spur is in an environment with only long-tounged flies, they will evolve long spur length.

● Therefore, long spur goes with Long-tongued fly & vice versa.

63
Q

Spur?

A

= part of a flower that allows itself to be pollinated.

64
Q

Interpreting pattern of speciation from phylogeny attributes? (2)

A

• Dating the phylogeny relative to understanding the history of the landscape helps (historical biogeography).
• Match phylogeny to distribution OR distribution to phylogeny.

BIO3A: Processes 2 Patterns (12 decks)

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