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BIOL 208 > Intro to Community Ecology > Flashcards

Intro to Community Ecology Flashcards

1
Q

What is a community in ecology?

A
  • an association of interacting species inhabiting a defined area at a particular scale over a particular span of time
  • communities are often considerations of a particular group (taxonomic, guilds, life form, funcitonal)
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2
Q

Guild

A

species living in the same way
- e.g., use same resources

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3
Q

life form

A

species that have a similar growth form

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4
Q

functional group

A

species with a similar ecological function or attribute

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5
Q

What Types of Species are in Community Ecology? (three types)

A
  • foundational species
  • keystone species
  • invasive species
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6
Q

Foundational species

A
  • species which provide a key role in shaping structure within a community
  • e.g., coral reefs (provide food, shelter, breeding areas, and refuge for marine life)
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7
Q

Keystone species

A
  • species that have a disproportionate impact the community structure relative to the abundance of other species
  • if removed the loss of keystone species leads to a dramatic change in structure
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8
Q

Invasive species

A
  • species that are not native to the habitat and disrupt the community
  • characterized by an inability to grow quickly and reduce local biodiversity
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9
Q

How is Community Structure Described?

A
  • the relative abundance of species within the community
  • the number of species and diversity
  • species composition
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10
Q

What is community diversity a combination of?

A

the total number of species there are as well as their relative abundance

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11
Q

Species richness

A

the number of species in a community

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12
Q

Species Evenness

A

the relative abundance of the various species within a community

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13
Q

Species Diversity

A

a measure of diversity that increases with species evenness and species richness

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14
Q

What is Species Abundance and how is it measured?

A
  • measure of how common or rare a species is
  • measured depending on the life history of the species in particular
  • number of individuals, species cover, species biomass
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15
Q

Number of Individuals

A
  • a measure of species abundance
  • used when organisms form distinct entities, like birds
  • not useful for clonal organisms
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16
Q

Species Cover

A
  • a measure of species abundance
  • visual estimation
  • used when identifying individuals is not trivial, like in algae, plants
  • quick and non-destructive but less precise
17
Q

Species Biomass

A
  • a measure of species abundance
  • quantifiable as fresh or dry weight
  • used when identifying individuals is not trivial like in plants
  • slow and destructive, but more precise methods
18
Q

Species Dominance and Why is it Important?

A
  • species that is more common than all others
  • may be measured as biomass, area occupies, # of individuals, etc.
  • most species in the community will occur in moderate abundances
  • is important because if only one or two species dominate a community, a majority of the interaction within that community will involve those species
19
Q

Species Abundance Distributions

A
  • abundance is usually quantified in relative terms - and graphed using a lognormal distribution
  • aka population size with respect to the total number of individuals in a community, regardless of species or percent cover with respect to the total area of a patch
20
Q

Why are Abundance Curves not always ideal

A
  • how well we can fit a lognormal distribution curve depends on sampling effort
  • overlooking rare species happens often
  • the more you sample, the more species you will find and the closer your abundance distribution will resemble a lognormal distribution curve
21
Q

What are the three types of species diversity? What is their significance?

A
  • Gamma: diversity within a region/landscape
  • Alpha: diversity within a particular area within a region/landscape (a subset of gamma)
  • Beta: a measure of the diversity among locations within a region, usually measured as the amount of species change between ecosystems calculated as gamma/alpha
22
Q

What is Species Evenness?

A
  • the relative population size of each species
  • an ecosystem dominated by one species will have low evenness
23
Q

What is Biodiversity and how is it calculated?

A
  • biodiversity is species richness AND evenness
  • calculated by the Shannon-Wiener Diversity Index (H’)
24
Q

How do we calculate Species Evenness?

A
  • using Pielou’s J
  • J= H’ / ln(s)
25
Q

How do we determine how even a community is using Pielou’s J

A
  • closer to 1 = more even
  • closer to 0 = less even
26
Q

Rank Abundance Curves, and What is their Significance ?

A
  • they are a plot of relative abundance of species
  • these are useful because they allow ecologists to visually portray species dominance/diversity patterns within a singly community or among communities
27
Q

Explain how to read a rank abundance curve

A
  • each dot represents the relative abundance of a species
  • dots ranked according to their abundances, with high-abundance species plotted on the left side of the curve
  • the flatter the curve (aka decreased), the more even the community
28
Q

What are the factors that increase/decrease biodiversity?

A
  1. time: the more uninterrupted time to evolve/colonize, the higher biodiversity
  2. global change: pollution, habitat destruction, landscape homeogenization, invasive species decrease biodiversity
  3. complexity: the more complex, the higher biodiversity
  4. exploitation and limitation: some predators or herbivores, or nutrient limitation decrease competition and increase biodiversity
29
Q

What is included in a more complex environment?

A

vertical structure, water movement, nutrient availability, light availability,etc

30
Q

What is species composition?

A

the species that occur in a given community at a given time

31
Q

Why is considering species composition important?

A

ecological functions performed by communities are dependent upon community structure
- compositional changes can indicate shifts due to environmental or anthropogenic effects
- concern rises when compositional shifts impact the delivery of ecological services - processes that are of value to humans

32
Q

What are some examples of ecological services?

A
  • biomass production
  • carbon sequestration
  • nutrient cycling
  • crop pollination
  • water filtration
  • etc.
33
Q

How does species diversity influence ecological function? (three main mechanisms)

A
  • complementarity
  • facilitation
  • species selection/sampling effect
34
Q

Define Complementarity

A
  • comes from niche theory
  • a given ecological service will be at its greatest for communities in which all resources and/or microenvironments are being exploited/occupied
35
Q

Define Facilitation

A
  • some species may enhance the growth of others
  • ex. reducing soil salinity and/or altering the thermal environment
  • may be particularly important in stressful situations
36
Q

What is species selection/sampling effect?

A
  • basic idea is that species differ in the inherent rates of delivery of ecological services
  • as the number of different species increase in a community over time, the odds of said community containing at least one species with enhanced function increases
37
Q

genetic diversity and ecological function relationship

A
  • increases in genetic diversity can lead to an increase in species diversity within a community
  • how? genotypes likely differ in : how species forage to resource, where plants put roots and leaves, susceptibility to disease, ability to outcompete rivals,etc.
38
Q

Are lakes simple or complex?

A

complex, have horizontal and vertical spatial complexity and can turn over

BIOL 208 (30 decks)

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