Community & Ecosystems Midterm

Progressive Utilitarian Conservation Ethic

1900s, Gifford Pinchot pushed for equal use of natural resources for present and future generations

Environmental Awakening

1960-70s, resource management included interests other than extraction and capitalization

Aspects of present day ecosystem management (5)

• non-equilibrium prospective

• holistic, large-scale considerations

• embraces uncertainty

• adaptive management

• consensus building: partnerships and collaboration

Population ecology

patterns and process involving single-species groups of individuals

Community ecology

maintenance, origin, and consequences of biological diversity within communities

• place based

• study of interactions between two interacting species

Ecosystem ecology

one or more communities together with their abiotic surroundings

Functional group

collection of species that use similar resources in a similar way

Assemblage

set of taxonomically similar group

Annie Alexander

established first vertebrae museum

Competition types (5)

• consumption: consuming the same resource

• preemption: physical resource is occupied

• overgrowth: one organism grows over another

• territoriality: aggressive behavior, exclusion of space

• encounter: non-territorial encounter

Competitive exclusion principle

no two spieces can compete to occupy the same niche

Colonial Sea Anemones case study

• Competing sea anemone colonies are territorial, and create unclaimed space from death of “soldier” anemones

• showed how competitive mechanisms disadvantage both groups

Intertidal zone case study

Intraspecific competition

competition within one species

Lotka Volterra model - Model for interspecific competition, describes predator-prey dynamics

population size of the competitor (i) weighted by competition coefficient

Competition coefficient that measures intraspecific competition relative to interspecific competition

What species wins in this, i or j?

i

What species wins in this?

Coexistence

Trade-off theory

species cant evolve to resistance to predation without trading abilities such as competitive abilities

HSS/ "Why is the World Green” Hypothesis

• points to predators as being big driver of community dynamics

• predators keep herbivores in check

• function of trophic levels

Keystone predation

predation increases species richness

• when predators feed on competitive dominant, it gives opportunity for other species

• density dependent

Predation case study (Paine)

• top-down predation maintains community structure and species diversity in rocky intertidal ecosystems

• Without Piaster, the competitive dominant mussel outcompeted the other species

Predation: Jane Lubchenco 1978

• Green algae was competitive dominant, snails prey on the algae

• Snail predation on green algae allows red algae to grow

Prey Lotka Volterra variables

• H = Number of prey

• P = number of predators

• b = per capita birth rate of prey

• a = per capita attack rate

• K = carrying capacity

• aH = per capita consumption rate

Predator Lotka Volterra variables

• e = conversion efficiency of consumed prey into new predators

• -s = rate at which predators die in absence of prey

• aH = per capita consumption rate

• P = number of predators

4 Categories of mutualism

• Energetic: energy obtained by one mutualist is made available to another

• Nutritional: transfer of nutrients, such as nitrogen phosphorous

• Protective: one mutualist provides active or passive defense

• Transport: involves movement of gametes, propagules, or individuals

Indirect mutualism case study Dodson et al.

• ponds have mole salamanders, and phantom midges

• both feed on zooplankton

  • salamanders eat large, midges eat small

• without the salamanders, the zooplankton grow too large for the midges to eat

Indirect mutualism

Benefits of the mutualism depends on a third species being present

Competition

Consumptive competition

Indirect mutualism

Keystone Predation

Apparent competition

mutualism

Indirect mutualism