Lecture 14 Flashcards
1
Q
Communities
A
- groups of interacting species that occur together at the same place and time
- Ecologists usually define communities based on physical/ biological characteristics
2
Q
Physically Defined
A
- might encompass all the species in a sand dune, a mountain stream, or a dessert
3
Q
Biologically Defined
A
- this approach emphasizes the importance of abundant species, such as trees
- Ex. kelp forest
4
Q
Ecologists usually consider a subset of _____
A
- species when they define and study communities
5
Q
Subset of Species can be Defined by
A
- taxonomic affinity
- guild
- functional group
6
Q
Taxonomic Affinity
A
- all bird species in a community
7
Q
Guild
A
- Group of species that use the same resources
8
Q
Functional Group
A
- Species that function in similar ways, but do not necessarily use the same resources
- Ex. C4 group
9
Q
Trophic Levels
A
- Primary producers (autotrophs) - plants and algae
- Primary consumers - herbivores
- Secondary consumer - carnivores
- Tertiary consumers - carnivores
10
Q
Food Webs
A
- tell little about the strength of interactions or their importance in the community
- do not include non-trophic interactions
11
Q
Horizontal Interactions
A
- competition
12
Q
Interaction Webs
A
- more accurately describe both the trophic (vertical) and non-trophic (horizontal) interactions than a traditional food wed
13
Q
Community Structure
A
- the set of characteristics that shape communities
14
Q
Species Richness
A
- the number of species in a community
15
Q
Species Evenness
A
- relative abundances compared with one another
16
Q
Species Diversity
A
- combines species richness and species evenness
17
Q
Biodiversity
A
- described diversity at multiple spatial scales
- From genes to species to communities
- Implicit is the interconnectedness of all the components
18
Q
Genetic Diversity
A
- affects the viability of populations
- Which in turn affects species diversity
- The number of community types in an area is critical to diversity at larger regional and latitudinal scales
19
Q
Rank Abundance Curve
A
- plot the proportional abundance of each species (pi ) relative to the others in rank order
20
Q
Relative Abundance
A
- suggest what species interactions might be occurring
- Community A, the dominant species might have a storing negative effet on the three rare species
- Experiments that add or remove species are used to explore these relationships
21
Q
Species Composition
A
- the identity of species in a community
- The identity of species is critical to understanding community structure
22
Q
Species Accumulation Curve
A
- species richness is plotted as a function of the total number of individuals that have been counted
- Curves can help determine when most or all of the species in a community have been observed
23
Q
Interaction of Multiple Species
A
- Communities can be characterized by complex networks of direct and indirect interactions that vary in strength and direction
24
Q
Direct Interactions
A
- occur between 2 species
- Ex. competition, predation, and facilitation
25
Q
Indirect Interactions
A
- occur when the relationship between 2 species is mediated by a third (or more) species
26
Q
A Trophic Cascade
A
- Strong linear relationship of direct effects between organisms that eat one another
- The negatives are causing -/+ affects
27
Q
Trophic Facilitation
A
- a consumer is indirectly facilitated by a positive interaction between its prey and another species
28
Q
Competitive Networks
A
- competitive interactions among multiple species in which every species negatively interacts with every other species
- Strong direct competition is buffered, competitive interactions weaker, and no one species dominates
29
Q
Interaction Strength
A
- magnitude of the effect of one species on the abundance of another species
30
Q
Dominant Species or Foundation Species
A
- have large effects on other species
- This species’ diversity, by virtue of their considerable abundance or biomass
31
Q
Ecosystem Engineers
A
- they create, modify, or maintain physical habitats for themselves and other species
- Are dominant species
32
Q
Keystone Species
A
- have a strong effect because of their roles in the community
- Their effect is large in proportion to their biomass/ abundance
- Usually influence community structure indirectly, via trophic means
- Some can be ecosystem engineers (ex. beavers)
- They are building dams that transform the swiftly flowing streams into marshes with wetland plants
33
Q
A
