Niche

1
Niche

• An organisms niche is its ecological role
• habitat address, niche job

Resource partitioning
2
Niche competition

• Competitive Exclusion
• No two similar species can occupy the same niche
  at the same time

3
Predation drives evolution

• Predators adaptations
• locate subdue prey
• Prey adaptations
• elude defend

horns, speed, coloration
spines, thorns, toxins
4
Trophic structure

• Food chains
• feeding relationships
• food chain usually 4 or 5 links trophic levels
• length of food chain limited by inefficiency of
  energy transfer

5
Energy transfer

• Energy in
• from the Sun
• captured by autotrophs producers (plants)
• Energy through
• food chain
• transfer of energy from autotrophs to
  heterotrophs (herbivores to carnivores)
• heterotrophs consumers
• herbivores
• carnivores

6
Energy inefficiency
incompletedigestion
metabolism
7
Pyramids of production

• represent the loss of energy from a food chain
• how much energy is turned into biomass

8
Food webs

• Food chains are hooked together into food webs
• Who eats whom?
• a species may weave into web at more than 1
  trophic level
• bears
• theres always a bigger fish

What limits the length of a food chain?
9
Implications

• Dynamics of energy through ecosystems have
  important implications for human populations
• what food would be more ecologically sound?

10
Disturbances

• Most communities are in a state of change due to
  disturbances
• fire, weather, human activities, etc.
• not all are negative

11
Disturbances

• Disturbances are often necessary for community
  development survival

12
Ecological cycle

• fire as part of a natural community cycle

13
Ecological succession

• The sequence of community changes after a
  disturbance
• transition in species composition over ecological
  time
• years or decades

Mt. St. Helens
14
Succession
Change in species mix over time

• From bare soil, then
• bacteria
• lichens mosses
• grasses
• shrubs
• trees

makesoil
15
Succession
from mosses lichens pioneer species
to shrubs trees
16
Climax forest
The species mix of climax forest is dependent on
the abiotic factors of the region

• solar energy levels
• temperature
• rainfall
• fertility depth of soil

birch, beech, maple, hemlock
17
Chapter 54
Ecosystems
18
Ecosystem

• Community of organisms plus the abiotic factors
  that exist in a certain area

19
Nutrient cycling
20
Carbon cycle
21
Nitrogen cycle
22
Phosphorus cycle
23
What have we done!
24
Impact of ecology as a science

• Ecology provides a scientific context for
  evaluating environmental issues
• Rachel Carson, in 1962,in her book, Silent
  Spring,warned that use ofpesticides such as
  DDTwas causing populationdeclines in
  manynon-target organisms

25
Barry Commoners Laws of Ecology

• Everything is connected to everything else
• Everything must go somewhere
• there is no such place as away
• Nature knows best
• There is no such thing as a free lunch

Laws of Unintended Consequences
26
Acid Precipitation

• nitrogen oxides
• sulfur dioxide

• power plants
• industry
• transportation

27
Acid rain
28
BioMagnification
29
BioMagnification

• PCBs
• General Electric manufacturing plant on Hudson
  River
• PCBs in sediment
• striped bass nesting areas