Ecosystems

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Ecosystems Living Organisms
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How Did Life Evolve?

• Best hypothesis
• Chemical Evolution
• 1 billion years
• Biological Evolution
• 3.7 billion years
• Prokaryotes--gt Eukaryotes--gt Diversification

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Characteristics of Kingdoms

• Archaebacteria
• Eubacteria
• Prokaryotes
• Single-celled
• Decomposers
• Help in digestion
• Can cause diseases

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Protista

• Eukaryotic
• One-celled
• Some algae
• Ponds and sea
• Some cause disease

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Fungi

• Eukaryotic
• Mostly multicellular
• Chitin cell wall
• Decomposers
• Mutualistic

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Plants

• Eukaryotic
• Multicellular
• Photosynthetic
• Cellulose cell wall
• Annuals and perennials

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Animals

• Eukaryotic
• Multicellular
• Heterotrophic
• No cell wall
• Invertebrates Vertebrates

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Biological Communities

• Producers Consumers
• Decomposers

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Biological Communities

• General characteristics
• Lack defined boundaries
• Organisms and interactions are never isolated

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Keystone Species

• Key members of community
• Need certain limited resources.
• Critical element when describing an ecosystem

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Keystone Species

• NOT always most abundant
• ALWAYS most important

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Keystone Species

• One of the keys to conservationist efforts
• Grey wolf of Yellowstone Park

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Why is the gray wolf a keystone species?

• Gray wolves eat elk. Leftovers provide food for
  ravens, eagles, and bears.
• Too many elk overrun important vegetation that
  provide habitat for birds and food for beavers.

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Interactions Among Organisms

• Predation
• Pursuit and ambush
• Plant defenses against herbivores
• Defensive adaptations

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What is Predation?

• Predation members of a predator species prey on
  members of a prey species, but do not live in or
  on the prey.

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Predator Strategies

• Structural advantages
• Natural Weapons - Fangs, claws
• Flexible bodies
• Larger Size

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Predator Strategies

• Ambush-
• Stalk a victim
• Gape Suck (fish)
• Keen eyesight
• Venom

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Predator Strategies

• SPEED CUNNING
• More intelligent than prey
• Run faster than prey
• Hunt in packs

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Prey Strategies

• Defense Techniques
• Inflate
• Flee
• Fight Back
• Stab
• Poison

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Prey Strategies

• Structural advantages
• Hard Body Coverings
• Thorns or Spines
• Break away body parts
• Natural Weapons

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Prey Strategies

• Chemical Warfare
• Blinding ink
• Poison
• Offensive Smells and Tastes

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Prey Strategies

• Camouflage
• Color Change
• Counter-shading
• Disruptive Patterns
• Mimicry

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Mimicry

• Mostly a prey technique
• Optical and sonic illusions
• LOOKS like a predator

• School of fish, false eyes, frilled neck, and
  inflation

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Predation Feedback Systems

• Positive feedback for predator
• gets to eat prey
• Negative feedback
• prey population falls, no food, decrease in
  predator population

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Interactions Among Organisms

• Symbiosis
• Mutualism
• Commensalism
• Parasitism

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Mutualism

• Both Species Benefit
• Rhinos and oxpeckers
• Trees and fungi

• Ants Acacia (ants keep other predators away
  from acacias)
• Pollination

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The Evolution of Mutualism

• Evolved from more negative associations
• Organism impacted had two options
• Escape relationship
• Or adapt to it make it self-advantageous

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An Example of Mutualism

• Ant and Aphid
• Ant protects aphids eggs, feeds larva, tends
  them, keeps them safe
• Aphid supplies the ant with food
• Honeydew it secretes from its body

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Mycorrhizae

• Symbiotic fungus
  found on plant roots
• Aids in water
  retention, mineral
  uptake

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Truffles

• Most expensive food in the world, by mass
• Only found on deciduous tree roots
• Cannot be
  cultivated
• Unique,
  delicious taste

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Rhizobia

• Symbiotic bacteria found in nodules on legume
  roots (soybeans, peas)
• Fix nitrogen
• Natural
  fertilizers

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Pollination

• Need insects, bats, birds, and some mice to
  assist them
• Animals eat nectar and pollen

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Obligate Mutualism

• Required for the survival of both species
• ex. Yucca and yucca moth, lichens

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Co-Evolution

• The Yucca Moth and the Yucca flower are
  mutualistic

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The Yucca Relationship

• Yucca gets pollinated
• Moth gets place to lay eggs and obtain food
• Pollination fluctuates non-randomly

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Commensalism

• One member is helped, the other neither benefits
  or is harmed
• Epiphytes and forest trees
• Pearl fish Sea Cucumber

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Parasitism

• and - relationship
• Parasite benefits, host loses
• Parasite usually smaller than host
• Parasites ARE NOT predators. They usually do not
  kill their hosts

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Nematodes
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The Ecological Niche

• Each organism has a role in an ecosystem (fills a
  niche). Think of a niche like a job.
• Fundamental niche the entire range of suitable
  conditions for a species, without taking into
  account predators or interspecific competition
• Realized niche the actual occupied niche

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Competitive Exclusion

• Two species with similar requirements cannot
  occupy the same niche. (Gauses Law)
• One will either die out, or one will have to find
  a new niche.

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Intraspecific Competition

• Between SAME species intense why?

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Interspecific Competition

• DIFFERENT species less intense, Why?
• Slightly different requirements

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Solving the Problem

• Leave
• Emmigrate
• Die
• Extinction
• Adapt
• Resource Partitioning

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Solving the Problem
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Limiting Factors

• Major factor in defining an organisms niche
• Tall trees cannot grow in desert
• Water is limiting

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Other Limiting Factors?

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