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ECO3A: Individs, Popns, Commun > Community Ecology (W13) > Flashcards

Community Ecology (W13) Flashcards

1
Q

Island biogeography?

A

= a field within biogeography that examines the ecological phenomena & diversification on islands.

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2
Q

Island biogeography focus?

A

Focuses on factors that affect species richness in naturally isolated communities.

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3
Q

Island Equilibrium Theory (IET) attributes? (6)

A

• There’s an equilibrium in species richness on an island.

• Area & distance relationships determine the species richness on an island.

• Species richess is as a result of the rate of extinction & the rate of immigration (rate of dispersal).

• Explain that bigger & nearer islands will have higher species richness than the smaller & further islands.

• High rate of immigration is often a consequence of less species richness.

• High species richness onan island, higher rate of extinction.

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4
Q

Ways through which extinction can occur? (2)

A

• Competitive exclusion.
• Predation.

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5
Q

Why is a high rate of immigration a common consequence of less species richness?

A

It’s because there are more niches to occupy.

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6
Q

Island Equilibrium Theory is AKA?

A

Equilibrium theory of island biogeography.

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7
Q

Island Equilibrium Theory/Equilibrium theory of island biogeography?

A

= states that the number of species on an island is governed by the migration of new species & the extinction of species already there.

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8
Q

Explain IET graph? (8)

A

● x-axis = species richness.

● left y-axis = rate of immigration.

● right y-axis = rate of extinction.

● Equilibrium = where extinction & immigration rates line graphs meet/cross.

● Crossed lines also represent Species 1 (S1) and Species 2 (S2) but on different island sizes and island areas.

● Immigration rate line graphs = decreasing line graphs (one for far island & one for near island from mainland).

● Extinction rate line graphs = increasing line graphs (one for large island & one for small island).

● Interpretation.

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9
Q

How might immigration & extinction rates vary with island size & island isolation? (2)

A

● By large islands support more species than small islands.

● By isolated islands having fewer species than less isolated ones.

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10
Q

Island area effect (Island area)?

A

= extinction rate is the driver in equilibrium & determines species richness on an island.

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11
Q

Island distance effect (Island distance)?

A

= immigration rate is the driver in equilibrium & determines species richness on an island.

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12
Q

Immigration rate via? (2)

A

• Colonization.
• Dispersion rate.

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13
Q

Immigration rate is associated with?

A

Island distance from the mainland.

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14
Q

Extinction rate is associated with?

A

Island area.

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15
Q

Metacommunities Theory?

A

= a set of local communities linked by the dispersal of one or more of their constituent species (potentially interacting species).

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16
Q

Metacommunities Theory attributes? (2)

A

• Spatailly delimited.

• Analysing patterns in metapopulations as an ecologist.

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17
Q

Paradigms/Views for metapopulations? (4)

A

• Patch-dynamic view (PD).
• Species-sorting view (SS).
• Mass-effects view (ME).
• Neutral view (NM).

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18
Q

PD view attributes? (2)

A

• Assumes that patches are identical & that local species diversity is limited by dispersal.

• Doesn’t consider heterogeneity of a community.

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19
Q

SS view attributes? (3)

A

• Emphasizes spatial niche separation above & beyond spatial dynamics.

• Dispersal is important because it allows for species compositional changes.

• Considers heterogeneity of the community.

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20
Q

ME view attribute?

A

Focuses on the effect of immigration & emigration on local population dynamics.

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21
Q

NM view attributes? (2)

A

• A perspective in which all species are similar in their competitive ability, movement & fitness.

• Focus is on equivalence.

22
Q

Thing to note on Metacommunities Theory?

A

Interactions occur across different populations (populations are separated spatially), that’s how it relates to island theory as there is immigration/dispersal of species from different populations. This in turn affects species richness & causes populations to be slightly similar.

23
Q

Biome?

A

= the largest land community unit recognized at a continental level.

24
Q

Biome attributes? (3)

A

• Distinct geographical region with a specific climate, vegetation & animal life.

• Consists of a biological community that formed in response to its physical environment & regional climate.

• Metacommunities at regional scales.

25
Q

SA’s major biomes/metacommunities? (4) F²SG

A

• Fynbos.
• Forest.
• Savanna.
• Grassland.

26
Q

Fynbos attributes? (3)

A

• Synonymous with the Cape Floristic region.

• Characterized by.

• Fire is a major influence on community processes (infrequent).

27
Q

What does fire help with in the Fynbos biome?

A

It allows for germination of the seed bank.

28
Q

What is the Fynbos bione characterized by? (3)

A

• Plants from the Restinacaea, Ericacaea & Proteacaea families.

• Infertile & leached soils.

• Low animal biomass.

29
Q

Fynbos biome location?

A

E. Cape.

30
Q

Forest biome attributes? (3)

A

• Occurs in patches around the country & are restricted to forest-free areas.

• Support evergreen trees & multi-layered herbaceous cover.

• Large mammals & birds are important Keystone species.

31
Q

Mean annual winter rainfall for Forest?

A

> 525mm.

32
Q

Mean annual summer rainfall in Forest biome?

A

> 725mm.

33
Q

Why are large mammals & birds important Keystone species in the Forest biome?

A

It’s because they disperse seeds & maintain gap processes which allow succession within the forests.

34
Q

Savanna biome attributes? (3)

A

• Largest biome in SA (46% land cover).

• Environmental factors delimiting the biome are complex.

• Fire & herbivory maintain woody cover.

35
Q

Savanna biome altitude?

A

0–2000m.

36
Q

Savanna biome rainfall?

A

235–1000mm/year.

37
Q

Savanna biome frost?

A

Occurs 0–120 days/year.

38
Q

Grasslands attributes? (4)

A

• Found on the high central plateau of SA from near sea level to 2850m above sea level.

• 2 categories.

• C4 grasses dominate throughout the biome except at the highest altitudes where C3 grasses dominate.

• Fire & grazing drive ecological processes in grasslands.

39
Q

Categories of grasslands? (2)

A

• Sweet grasslands.
• Sour grasslands.

40
Q

Sweet grasslands?

A

= low fiber content.

41
Q

Sour grasslands?

A

= high fiber content.

42
Q

How does SA characterize biomes? (3)

A

• Rainfall.
• Vegetation.
• Biotic factors (fire & grazing).

43
Q

Bush encroachment in grasslands & savanna biomes kinds of drivers? (2)

A

• Local drivers.
• Global drivers.

44
Q

Local drivers of ush encroachment in grasslands & savanna biomes? (3)

A

• Fire.
• Herbivory.
• Land use change.

45
Q

Global drivers of ush encroachment in grasslands & savanna biomes? (2)

A

• Temperature.
• CO2.

46
Q

Fire as local driver?

A

= affects tree densities, biomass & species composition.

47
Q

Herbivory as local driver?

A

= maintains open, grassy ecosystems through their impact on adult tree mortality.

48
Q

Land use change as local driver?

A

= leads to invasion of old …

49
Q

Temperature as global driver?

A

= low temperatures suppress sapling growth & high temperatures result in faster growth rates.

50
Q

CO2 as global driver?

A

= high CO2 increases plant growth rate & water use efficiency.

51
Q

When is bush encroachment bad?

A

Bush encroachment is bad if it leads to the collapse of a community.

ECO3A: Individs, Popns, Commun (11 decks)

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