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ECOL211 > Travis Ingram (L9-18 (not 11,12)) > Flashcards

Travis Ingram (L9-18 (not 11,12)) Flashcards

1
Q

What are the main processes in community ecology? What can change the relative abundance of species?

A

Selection
Ecological drift
Speciation
Migration

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2
Q

What is selection and its causes?

A

Some species have a higher expected reproductive output than others
Competitive exclusion, whichever species has the highest fitness should exclude the other
This can be caused by superior competitor for a shared resource, less vulnerable to a shared predator or pathogen, benefit more from a shared mutualist, more tolerant to environmental stressors

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3
Q

What is ecological drift and its causes?

A

In finite communities, some species will increase or decrease in relative abundance due to chance
This can be caused by demographic stochasticity (random variation in reproductive success even if underlying fitnesses are equal), occurs whether or not there are any fitness differences or niche differences between species

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4
Q

What is speciation and its causes?

A

New species arise over longer time periods
All species ultimately arose from other species, dating back to their universal common ancestor
Usually occurs in allopatry, species form when they’re geographically isolated long enough that they don’t interbreed and may later come into contact

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5
Q

What is migration and its causes?

A

When individuals of different species move between communities
Regular migrations occur at particular life stages or seasons
Directed or random dispersal between habitats
It can change the relative abundance of species, making multiple communities more similar and source-sink effects

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6
Q

What does the selection, ecological drift, speciation, and migration framework miss?

A

Trophic structure
Intraspecific variation

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7
Q

What is coexistence?

A

Stable coexistence is where species are expected to persist in the same community more or less indefinitely

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8
Q

What is co-occurence?

A

Species occur in the same community, though they may or may not stably coexist

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9
Q

What is mutual invasibility and the criteria for this?

A

If two species can coexist, then either should be able to establish at low density
Intraspecific competition is larger than interspecific competition
It requires some niche difference between species

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10
Q

What is neutral theory?

A

The theory that in a large community with many individuals, of competitively equivalent species can co-occur for a long time
Some species may not co-exist, but if they are competitively equivalent it might take thousands of years for one to disappear from a large pond due to ecological drift

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11
Q

What are the assumptions of neutral theory?

A

All individuals are competitively equivalent, regardless of their species identity
No differences in fitness (competitive ability) or niche (resource use), meaning no selection
No coexistence but no competitive exclusion either due to a lack of dominance, species co-occur until extinction by ecological drift (demographic stochasticity)
New species arise via speciation, and move between patches via migration

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12
Q

What does competitively equivalent mean?

A

Mortality depends on the density but not the frequency

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13
Q

What is the modern coexistence theory?

A

Coexistence depends on niche differences being greater than differences in competitive ability
Key components are niche differences and fitness differences

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14
Q

What are the stabilising effects?

A

Niche differences between species
Different resource use
Storage effect
Using resources at different times
Different responses to environmental variation

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15
Q

What are the equalising effects?

A

Decreasing with fitness difference
Smaller fitness differences between species

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16
Q

Successes of the neutral theory?

A

Damselflies - Enallagma ebrium and Enallagma vesperum
Found that coarse patterns like species abundance distribution can’t really distinguish between neutral theory and niche-structured communities
The assumption of competitive equivalence is usually found to be false
Got people thinking about ecological drift and the need to distinguish coexistence vs co-occurrence

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17
Q

What is community assembly?

A

The process by which species from a regional pool colonise and interact to form local communities

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18
Q

What is the spatial scale of communities?

A

There are different scales based on the species we are looking at, but if a local community is a group of interacting species occurring in the same place at the same time, we can roughly define communities using movement distances of individuals

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19
Q

What is a regional pool?

A

All the potential colonists of a local community, within a reasonable dispersal distance

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20
Q

What do species need to be able to do to be present in a local community?

A

Be able to colonise the site (present in the regional species pool)
Be able to tolerate the local abiotic environment
Be able to coexist with the other species present (biotic environment)

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21
Q

Intraspecific competition = interspecific competiton

A

Neutral theory

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22
Q

Intraspecific competition < interspecific competition

A

Competitive exclusion

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23
Q

Intraspecific competition > interspecific competition

A

Species passing through the biotic filter

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24
Q

What are the tests for regional effects?

A

Comparisons of average local diversity (α-diversity) with regional diversity (γ-diversity)

1:1 relationship - every species in the region occurs in every local community
Linear relationship - regional processes such as dispersal and speciation determine local diversity (species pool is important)
Saturating relationship - local processes such as selection and drift determine the local diversity

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25
Q

How does co-existence tell us about community assembly?

A

Traits and phylogenetic relatedness may reflect niche differences and fitness differences, which cannot be seen in graphs

26
Q

Does niche difference predict the probability of existence?

A

Yes, the larger the niche difference, the more chance of coexistence

27
Q

Does phylogenetic distance predict the probability of existence?

A

No, ecological similarity requires verification

28
Q

Experiment on community assembly

A

Experimental assembly on wetland plant communities
5 replicates x 24 treatments
Tracked over 5 years
Revealed the environmental conditions that limit the establishment of different species, as well as the role of stochasticity

29
Q

What is the island biogeography theory?

A

Big islands that are close to the mainland have a higher diversity than those that are smaller and further away

30
Q

What are metacommunities?

A

Local communities or patches that are connected by dispersal, which may be asymmetric (have different dispersal rates)

31
Q

What are reasons for bias in metacommunities?

A

Ocean currents, wind, sun, productivity of islands, closeness of islands

32
Q

How is diversity in metacommunities measured?

A

α-diversity = at the local community scale
β-diversity = turnover between communities (helps to scale whether it is local or regional)
γ-diversity = in the entire region/metacommunity

γ = α*β
β = γ/α

33
Q

How important are dispersal/migration, abiotic factors, and biotic factors on the Neutral Theory?

A

Model 1 - the metacommunity is a set of homogenous patches, and species have no niche or fitness difference
Dominated by dispersal

34
Q

How important are dispersal/migration, abiotic factors, and biotic factors on Patch Dynamics?

A

Model 2 - the metacommunity is a set of homogenous patches that are periodically emptied by disturbance
Dominated by migration and biotic factors (competition)

35
Q

How important are dispersal/migration, abiotic factors, and biotic factors on Species Sorting?

A

Model 3 - the metacommunity is a set of heterogenous patches, and species fitness varies among patch types
Dominated by selection (biotic) following migration

36
Q

How important are dispersal/migration, abiotic factors, and biotic factors on Mass Effects?

A

Model 4 - the metacommunity is a set of heterogenous patches, but dispersal from more productive patches prevents complete species sorting (source-sink)
Dominated by migration, but there is a large interplay between all 3 processes

37
Q

What are some ways to study metacommunities?

A

Observational studies (environment vs distance)

38
Q

Metacommunity study (protozoa)

A

Protozoan communities in pitcher plants
Studied the effects of migration and selection on local species richness
Treatment replicated 5 times and tracked for 8 weeks
Saw an increase in dispersal with no predator, meaning competition is a major process in this environment

39
Q

Metacommunity study (arthropods)

A

Effects of selection (wet habitat vs dry habitat) and migration on mite diversity
4 replicates on metacommunity type, tracked over 14 weeks
Low migration - found that the amount of high quality habitat determines local diversity
High migration - found that heterogeneity increases diversity and mass effects allow for the co-occurrence of wet and dry habitat specialists

40
Q

What is a food web?

A

A network of trophic and feeding interactions

41
Q

How is trophic transfer efficiency measured?

A

By the proportion of energy at one trophic level that is converted to energy at the next trophic level

42
Q

What is the Rule of 10%?

A

10% of the energy at one trophic level is transferred to the one above

1 - sharks
10
100
1000 - plants
Biomass trophic pyramids can be inverted when the producer biomass is low, unlike energy trophic pyramids

There is a maximum trophic level of around 6 due to not enough energy transfer through the trophic levels

43
Q

What is a trophic subsidy?

A

Allochthonous (produced elsewhere) material can move between ecosystems and alter the food web structure

44
Q

Study on trophic subsidies

A

Studies between streams and forests
8 reaches
2 replicates x 4 treatments
Reduced the input of terrestrial arthropods
Fish depleted the stream invertebrates only in the absence of terrestrial ones
Trophic cascade increases the stream autochthonous algae production

45
Q

What is bottom up control, and an example of this?

A

Limitation by the productivity of lower trophic levels
Nutrient limitation in lakes
Coastal marine ecosystem productivity across multiple trophic levels

46
Q

How to tell if bottom up control is occurring?

A

If there are high numbers in low trophic levels, bottom up control is occurring

47
Q

What is top down control and an example of this?

A

Limitation by exploitation from higher trophic levels
Predators limiting herbivores, primary producers are released from grazing (why the world is so green)
Predator prey cycles

48
Q

How to tell if top down control is occuring?

A

If there are higher numbers in higher and lower, but not middle (herbivory) trophic levels, top down control is occurring

49
Q

What does omnivory do to prevent trophic cascades?

A

Makes the trophic levels less distinct

50
Q

What does donor control do to prevent trophic cascade?

A

Provides allochthonous material whose supply isn’t under top down control
It can only be reduced once it gets there, but cannot control the supply

51
Q

What are the ecological consequences of eutrophication?

A

Harmful cyanobacteria blooms
Anoxic or hypoxic dead zones
Shading of benthic macrophytes
Loss of aesthetic/recreational value

52
Q

What are some strategies to mediate eutrophic lakes?

A

Treat the disease at its source by reducing the bottom up effect of nutrients
Treat the symptoms by manipulating trophic structure (biomanipulation)

53
Q

How does biomanipulation work?

A

Introducing or enhancing piscivore populations and/or reducing planktivorous fish populations, only if these fish are okay to be in the system
Allowing for daphnia species to return and increase water clarity

54
Q

How has biomanipulation been used in Finland?

A

Cultural eutrophication due to industrial waster and domestic sewage from 1870-1970
Nutrient inputs were reduced by 1980 but toxic cyanobacterial blooms still occurred, suggesting legacy effects

Stocking of piscivorous pikeperch, massive removals of planktivorous roach

55
Q

How has biomanipulation been used in New Zealand?

A

Reservoir in Zealandia
15k planktivorous juvenile perch culled
Zooplankton recovered, cyanobacteria declined
Perch population rapidly recovered, short term effects only
Native fish were removed
Lake was drained and rotenone and e-fishing was used to further cull the population

56
Q

How can biomanipulation be used to increase primary production?

A

Biological control of agricultural pests
Algal biofuel production
CO2 sink to limit warming (top down control of CO2 flux)

57
Q

What are the climate effects on ectotherm species?

A

Warming increases metabolic rate and activity, up to species-specific thermal limits

58
Q

What are the climate effects on endotherm species?

A

Metabolic rate is lowest in the thermoneutral zone

59
Q

How does acidification affect species?

A

Reduced calcification
Variable effects on growth and physiology

60
Q

What are some ways to predict the climate effects on food webs?

A

Observational studies - realistic but correlative and limited to presently observed climates
Models combining single species predictions - thorough by labour intensive, hard to scale beyond a few species
Predictions from metabolic theory - general but paints a broad brush and may miss the details
Experiments - the best way to isolate drivers and control for other variables, crucial to get the scale and form of manipulation right

ECOL211 (3 decks)

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