Carnivory

Parasitism

parasitoids

cannibalism

herbivory

1. In the absence of predators, prey populations grow exponentially- assume unlimited resources

2. In the absence of food, predator populations decline exponentially 

These predator prey populations oscillate, but few good examples in natural populations

1. prey have a spatial (hiding) or temporal (eating at different times) refuge

2. optimal foraging: predators switch to other prey as original prey species fall to low abundance

3. antipredator strategies:

-chemical defense: aposematic coloration (to warn) and poison

-camouflage: cryptic coloration and mimicry

-displays of intimidation and fighting

-agility

-armor

-altered reproductive patterns: masting, so many offspring you overwhelm predator 

Gleason

communities are chance assemblages of species with similar abiolic requirements

a more general way to say nonequilibrium view

Clements

communities are assemblages of dependent closely linked species 

a general way to say equilibrium view 

1. open biological systems

2. one way flow of energy

3. cycling of nutrients: energy imput from the sun is made into nutrients

group species by functional similarity

defined by the number of steps through which energy passes to reach the organisms in it

1. primary producers

2. primary consumers: herbivores, decomposers, detritivores (eat primary producers)

3.secondary consumers (eat primary consumers)

4. tertiary consumers (eat secondary consumers)

5. quarternary consumers (eat tertiary consumers)

forms a hierarchy of feeding relationships- shows flow of energy through ecosystem

most communities only have 3-5 trophic levels 

Odd number of trophic levels means...

Even number of  trophic levels means...

odd- resources limitation

even- consumer limitation 

an event that removes organisms and alters resource availability

communities with very high or low disturbance have lower species diversity than communities with moderate disturbance

1. when disturbance is severe and frequent community is composed of good colonizers (r-selected) with high reproductive rates

2. when disturbance is mild and rare community is composed of good competitors (k-selectors)

Species diversity is highest where disturbance is moderate (intermediate) in severity and frequency- allows both colonizers (r) and competitors to coexist (k)

1. disturbance in diverse communities is dampened by large numbers of interacting species 

2. the effect of disturbance is less than it would be in a species poor communities 

Higher diversity increases community stability 

Transition in species composition over time 

Primary succession: bare soil, no organisms

Secondary succession: soil, some organisms

1. Early successional communities (r-selection): good dispersers (colonizers) and high reproductive rates

2. Late successional communities (k-selection): good competitors, exist near carrying capacity

1. Directional succession: progressive change in species composition 

2. cyclical succession: change in species composition in which the original community is ultimately restored 

Invasive species: species that disrupt communities by a dominant colonization of a particular habitat or from loss of natural controls (predators or herbivors)

Impacts: changes in ecosystem structure and function

Environmental disturbance promotes biological invasion which can alter native succession and promote more invasion

the wider the average niche breadth the fewer the number of species in the community (extinction via competitive exclusion)

the narrower the average niche breadth the more species in the community (coexistence via resource partioning)

Predation may increase richness by allowing compeitively inferior species to coexist with superior competitors 

a species influence on the community is greater than would be expected on the basis of abundance 

moderate levels of predation increase species diversity

species richness is positively correlated with island size and negatively correlated with distance from the mainland 

if extinction is greater than immigration then species diversity decrease

if extinction is less than immigration then species diversity increases

1. communities are structured by biotic interactions (competition, predation, herbivory)

2. communities display global stability

3. niche diversification determines species diversity

interactive hypothesis

1. communities composition is always changing and never in balance

2. no global stability

3. communities are patchworks of disturbance. Colonization and dispersal determine species diversity 

individual hypothesis 

1. genetic diversity (amount of genetic variation among species)

2. species diversity (number and relative abundance of species)

3. ecosystem diversity (diversity of structure and function in an ecosystem)

Conserve biodiversity because of economic value, ecosystem services, and environmental ethics 

each individual added actually increases the population 

trees: more of them, work together to bring up the water

flamingos