Ecology:

1
Ecology

• The study of interrelationships of organisms with
  one another and with the environment

2
Levels of Organization

• Organism one individual organism
• Species organisms sharing similar genes
  that can reproduce and have fertile offspring
• Population a group of the same species
• Community a group of populations
• Ecosystem a community plus all of the
  non-living parts of the ecosystem

3
Organism Interactions

• Trophic Relationships

4
Food Chains/Trophic Relationships

• Grass lt------Rabbitlt---------Hawk
• Producer 1o Consumer 2oConsumer
• Autotroph Heterotroph Heterotroph
• Herbivore Carnivore

5
Trophic Levels

• In ecosystems, feeding roles called trophic
  levels
• Organisms grouped into food chains, always
  starting with a producer

6
Food Web
It is more realistic to portray food chains as a
complex food web
7
Trophic Pyramids

• Food chains can be represented by a pyramid, with
  the producer at the bottom and the top predator
  at the top
• Pyramids represent amount of numbers, biomass,
  and energy

There are more producers than primary consumers,
and so on.
8
Pyramid of BiomassThe mass of all producers is
greater than mass of primary consumers, and so on
9
Pyramid of EnergyThere is more energy available
in producers than primary consumers, etc.
Available energy is lost at each step
10
Organism Interactions

• Predator/Prey Relationships

11
Predator/Prey Defenses Against Predators
Warning coloration (warns of toxins)
Cryptic coloration (camouflage)
12
Defense Against Predators Mimicry

• Batesian Mimicry resembling a distasteful
  species without being toxic itself ex. Monarch
  butterfly (toxic) and Viceroy

• Mullerian Mimicry group defense, all toxic
  members resemble each other

13
Predator/Prey Population Interactions

• Population of prey has to be higher than
  predator, populations fluctuate in cycles, with
  predator following prey

14
Organism Interactions

• Competition

15
Competition

• G.F. Gause created the Competitive Exclusion
  Principle No two species can occupy the same
  niche
• Niche the total relationship of an organism to
  its environment
• Two types of competition Intraspecific (among
  species) and Interspecific (between species)

16
Competitive Exclusion?

• Red Tailed Hawk
• Prey on mice and rodents
• Live in trees
• Live in less dense forest
• Hunt during day

• Great Horned Owl
• Prey on mice and rodents
• Live in trees
• Live in more dense forest
• Hunt during night

17
Introduced Species Competition with native
species
Zebra Mussels
Purple Loosestrife
Gypsy Moth
Codium
Mongoose
18
Organism Interactions

• Symbiosis

19
Symbiosis

• Commensalism - one organism benefits, other
  unaffected JK
• Mutualism - both organisms benefit JJ
• Parasitism - one organism benefits, other harmed
  JL

20
Which types of symbiosis?
21
Biomes

• Biomes are large distinct ecosystems with
  characteristic organisms and climate

22
Distribution of Biomes on Earth
23
Tropical Rain Forest

• Most diverse biome
• Characterized by tall trees, a dense canopy and
  vines
• Exploited and endangered - half of this biome has
  been destroyed for cash crops despite poor soil
• 90-100 rain/year

24
Desert

• Deserts cover 1/3 of the earths surface and are
  spreading because of overgrazing
• Vegetation includes cacti and thorny bushes
• lt10 rain/year

25
Grassland

• Most has been converted to farmland due to rich
  soils
• Good for crops and grazing animals
• 10-30 rain/year

26
Temperate Deciduous Forest

• Most exploited biome
• Only about .1 of original forest remain
• This is our biome
• 30-80 rain/year

27
Coniferous Forest (Taiga)

• Logging has stripped many parts of this biome
• Vegetation primarily evergreen trees
• 15-40rain/year

28
Tundra

• Vegetation limited, mostly lichens, moss and
  grasses
• Not enough precipitation for trees
• permafrost frozen soil
• lt10rain/year

29
Ecological Succession

• Succession is the aging of a habitat
• Two types Primary Succession and Secondary
  Succession

30
Primary Succession

• In Primary Succession, organisms colonize bare
  rock or soil where plants have not grown before
• Lichens often act as a pioneer organism
• Lichen-Moss-Large plants-Trees
• Reach Climax Community, definitive stage of
  growth

31
Secondary Succession

• In secondary succession, plants and organisms
  colonize a previously colonized area that has
  been disturbed by natural or human interference
  such as fire, floods, volcanoes, drought, storms,
  agriculture, development

32
General Principles of Succession

• Pioneer species colonize a bare or disturbed
  site.
• Changes in the physical environment occur (e.g.,
  light, moisture).
• New species of plants displace existing plants
  because their seedlings are better able to become
  established in the changed environment.
• Newly arriving species alter the physical
  conditions, often in ways that enable other
  species to become established.
• Animals come in with or after the plants they
  need to survive.
• Eventually a climax community that is more or
  less stable will become established and have the
  ability to reproduce itself.
• Nutrients are efficiently cycled in later stages

33
Population Growth Models

• Biotic Potential Rate at which a population of a
  given species will increase when no limits on
  rate of growth
• Rate of change of population where Nindividuals
  in population and rintrinsic rate of growth

34
Population Growth Curves

• Exponential J Curve, unlimited growth ex. Human
  population, annual plants
• Logistic S Curve, limited growth, population
  reaches carrying capacity ex. Organisms moving
  into empty niche

35
Population Growth Strategies

• K Strategists
• K refers to carrying capacity
• Delayed reproduction
• Small broods
• Few offspring
• Much parental care
• Typical of mammals,

• r Strategists
• r refers to intrinsic rate of growth
• Early age of first reproduction
• Large brood size
• Many offspring
• No parental care
• Typical of lower animals (invertebrates)

36
Population Limiting Factors

• Availability of raw materials(water, minerals)
• Availability of energy (food, sunlight)
• Accumulation of waste
• Interactions between organisms (predation,
  competition, parasites)