Co-evolution Flashcards

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1
Q

Define co-evolution.

A

The evolution of reciprocal adaptations of 2 or more species that have prolonged close interactions

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2
Q

Co-evolution is expected in…

A
  • mutualism (++)
  • parasitism (+-)
  • competition (–)
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3
Q

Co-evolution is unlikely in…

A
  • commensalism (o+)

- amensalism (-o)

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4
Q

Give the 2 types of mimicry.

A

Mullerian & Batesian.

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5
Q

Define Mullerian mimicry.

A
  • likely to exhibit reciprocal evolutionary patterns since both species involved are unpalatable and so have the opportunity to affect the evolution of each other’s colour patterns.
  • the more abundant species is usually the model since it is what the selective agent (predator) is cueing on.
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6
Q

Define Batesian mimicry.

A

-may not involve co-evolutionary phenomena as the evolution of colour is asymmetric (one is unpalatable).

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7
Q

Define adaptive radiation.

A

spread of new species of common ancestry into different niches, involving an excess of cladogenesis over extinction

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8
Q

Define convergent evolution.

A

organisms not closely related. Independently evolve similar traits as aa result of having to adapt to similar environments or ecological niches.

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9
Q

What does diversification into different niches permit?

A

The coexistence of multiple species.

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10
Q

What are KEIs

A

Key evolutionary innovations, they drive diversification.

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11
Q

Factors that promote adaptive radiation.

A

INTRINSIC
-metabolic & physiological opportunities eg crassulacean acid metabolism, endosymbiosis, toxins.
-developmental opportunities eg Hox genes and segmentations, wings and flight, dispersal.
-efficient dispersal (some organisms lack the ability to disperse over wide ranges)
EXTRINSIC
-empty habitats
-novel environments
-intensity of selection
-founder effects
-ecological release – occurs when a species expands its niche within its own habitat or into a new habitat where there is little competition for resources, which remain abundant (also release from predators and disease).

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12
Q

Example of adaptive radiation.

A

Lake Malawi, ~400,000 years old (up to 2 million).

Single cichlid species >200,000 years ago has since diversified into approx. 1,000 different species

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13
Q

Give the model of vertebrate evolution based on lake Malawi Cichlids Streelman and Danley put forward.

A
  1. Divergence of lineages into different major habitats
  2. Morphological specialization leading to trophic differentiation within habitats
  3. Sensory communication diversification- sexual selection
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14
Q

Give 2 examples of convergent evolution.

A
  • marsupial and placental mammals

- African euphorbias and north American cacti

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15
Q

Give an example of molecular convergent evolution.

A

-Antarctic fish vs Arctic fish
-Antarctic fish produce glycoproteins
-Arctic fish produce unrelated anti-freeze proteins
Independent episodes of molecular evolution occurred, with the same functional results.

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16
Q

Evidence of adaptive radiation.

A

homologous structure.

17
Q

Evidence of convergent evolution.

A

analogous structure.

18
Q

Limitations of convergent evolution.

A
  • contingency
  • functional/physical constraints
  • developmental constraints
  • genetic constraints
19
Q

How can adaptive radiation be proved?

A
  • a recent shared origin of members of the radiation
  • an accordance between diverse genetically based phenotypic traits and their divergent environment
  • a benefit of the specific phenotypic trait in the correlated environment
  • relatively high rate of lineage splitting
  • link between a key evolutionary innovation and rapid diversification
20
Q

Fitness decides the outcome of selection, therefore adaptations are described in terms of

A

their ability to promote fitness

21
Q

Give examples of fitness.

A
  • viability
  • growth
  • foraging efficiency
  • longevity
  • fecundity
22
Q

Give experimental approaches to adaptation.

A
Manipulate species
-population size
-variation (asexual vs sexual, in-breeding/outbreeding)
-attributes (size, colour)
-modify (biomimetics of a tail or wing)
Manipulate environment
-modify species composition
-exclude or add predators/hosts
-alter physical factors (temp, humidity)
23
Q

Give a way to measure the contribution of an adaptive trait.

A

modify or inactivate it, then study the consequences for fitness

24
Q

Why are microbes a good model for evolution?

A
  • easily propagated
  • rapid generation times
  • large population sizes
  • easily stored
  • environment readily controlled
  • asexual or sexual
  • single or mixed gentype
  • phenotypes are easily detected
  • whole genome sequencing
  • direct genetic manipulations possible
25
Q

Summarise paper on adaptive radiation in a heterogenous environment

A

Stated aim: examine role of ecological opportunity and competition in driving genetic diversification.

Stated conclusions:

  • ecological opportunities promote morphological diversification
  • ecological homogeneity does not promote divergence
  • mutation and selection alone are sufficient to promote new designs
  • competition amongst niche variants maintains variation
  • trade-offs in competitive ability drive adaptive radiation