Lecture 22: Dispersal, Metapopulations, and Island Biogeography Flashcards

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1
Q

How is sweet, fleshy fruit an adaptation?

A

It attracts animal pollinators which can disperse the seeds in their stool (heavier seeds can be dispersed this way when they cannot be dispersed by wind or water)

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2
Q

Dispersal allows organisms to

A
  • colonize new areas
  • escape competition
  • avoid inbreeding depression
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3
Q

metapopulation and metacommunity

A
  • collections of spatially distinct populations connected via dispersal
  • set of local communities linked by the dispersal of one or more of their constituent species
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4
Q

patch

A

each spatially distinct population within a metapopulation

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5
Q

source-sink dynamics

A

one patch is a source the other is a sink (locally extinct without being globally extinct)

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6
Q

Areas which can often be locally unstable but globally stable

A

archipelagos (each island can have different population dynamics) so long as there is occasional dispersal between islands

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7
Q

What is tracked with patch dynamics

A

patch occupancy through time (instead of individuals)

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8
Q

Colonization of patches is affected by…

A

Fraction of currently occupied patches (P)

  • higher P means more colonizers
  • but also higher P means fraction of empty patches available to colonize is less
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9
Q

Metapopulation structure facilitates

A

species persistence and coexistence

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10
Q

If species A always outcompetes species B within a habitat patch…

A

local coexistence is impossible, but global coexistence could be possible

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11
Q

Global coexistence of species A and B requires (when A always outcompetes B in a patch)

A
  • that A must go extinct in a patch OR new patches must be created from time to time
  • B must be a better disperser than A
  • B must be a fugitive/tramp/weedy/opportunistic/transient species
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12
Q

When local coexistence is impossible but global coexistence is, this is known as a…

A

competition-colonization tradeoff

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13
Q

populations can be driven to extinction by…

A
  • stochastic forces: chance fluctuations in population numbers
  • competitive exclusion
  • predator prey interactions
  • Allee effects at low density
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14
Q

Without migration…

A

patches that went extinct would stay extinct

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15
Q

What determines the number of species on an island?

A
  • colonization: species can arrive from elsewhere
  • extinction: species can go locally extinct on an island
  • in-situ speciation: a lineage can split in two on an island but it will be a very slow process
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16
Q

Goal of the Theory of Island Biogeography

A

to predict the number of species on an island from the island’s size and isolation (distance from the mainland)
- only considers colonization and extinction

17
Q

Which island would you expect to have more species: an large island 3 km from mainland or a smaller island 10 km from the mainland? Why?

A

The larger island because it is easier to colonize something from closer by and equally so the large island because species are less likely to go extinct when there is more habitat (conducive to more species living there less comp)

18
Q

Species richness tends to…

A

increase with area, decrease with isolation

19
Q

habitat fragmentation

A

suitable habitat in an inhospitable matrix (kind of like an island but on land; island of suitable habitat)

20
Q

How are metapopulations used to describe disease dynamics?

A

Hosts are like islands, area (or usable resources) and isolation matters for population dynamics of the disease.

21
Q

Environmental Stochasticity

A

Seemingly random events caused by environmental changes that influence how a population changes in size through time.

22
Q

Demographic Stochasticity

A

chance sequences of births or deaths in a small populations

23
Q

Variability increases around the…

A

carrying capacity (K) in the discrete logistic growth model as the growth rate (lambda) increases.

24
Q

Deterministic Chaos

A

make population dynamics looks very noisy but the value in one timestep depends exactly on the value in the preceding timestep