Ecosystems

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Ecosystems

• Part 1

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Levels of organization
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Levels of organization
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What is a species?

• Basic unit of biological classification
• Organisms that resemble each other, that are
  similar in genetic makeup, chemistry, and
  behavior, and that are able to interbreed and
  produce fertile offspring

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Is it a species?
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Vocab

• Intra within
• Intraspecific interactions ??
• Inter Between
• Interspecific interactions ??

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Population Dispersal patterns

• Clumped most individuals are together
• In environments with patchy resources
• Most common in nature
• Random little interaction between members of a
  species
• In environments with consistent resources
• Uniform found when distance between neighbors
  is maximized
• Arises from competition for a resource

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Population dispersal patterns the visual
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Ecological Niches

• Definition ???
• Influenced by the physical environment
• Take into account
• Interactions with the biotic and abiotic
  environment
• Available resources
• To describe
• Organisms adaptive traits
• Habitat
• Place in the food web

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Generalist vs. specialist

• Generalist live in broad niches and withstand a
  wide range of environmental conditions
• (K-selected)
• Specialist live in narrow niches and sensitive
  to environmental change
• (r-selected)
• Who has the advantage in the environment?

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Law of Tolerance

• The existence, abundance, and distribution of
  each species depends on the species tolerance to
  both the physical and chemical factors of the
  environment
• Limiting factor any factor in the environment
  that limits the growth of a population

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Resource partitioning

• Species share a resource and avoid direct
  competition with each other
• Types
• Temporal use resource at different times
• Spatial use the resource in different areas
• Morphological evolves different characteristics
  to use the resource

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Ecosystem Community Characteristics

1. Physical appearance relative size,
   stratification, distribution of the populations
   and species
2. Species diversity number of different species
3. Species abundance number of individuals of each
   species
4. Niche structure number of ecological niches, how
   they resemble or differ from each other, species
   interactions

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Biological Interactions amongst species
Interaction Description Example
Amensalism One species suffers and the other is not affected -due to scarce resource -usually occurs with when one organism engages in chemical warfare Black walnut tree releases a chemical to kill neighboring plants
Commensalism One species benefits and the other is not affected Transportation Housing Use of something created Shark and ramora Epiphytic plants Hermit crabs
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Biological Interactions amongst species
Interaction Description Example
Competition Interference directly between individuals Exploitation indirect by depleting a common resource Apparent indirectly when sought by same predator Elk and moose foraging Grass and trees using water Wolves hunting elk and moose
Mutualism Interaction where both species benefit Trees and mycorrhizal fungi
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Biological Interactions amongst species
Interaction Description Example
Parasitism One species benefits and the other is harmed -Tapeworm -cuckoo bird
Predation Predator hunts and kills prey for food -??
Saprotrophism Obtain nutrients from dead or decaying matter -Fungi -vultures -dung beetles
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Key Stone Species

• A species whose presence contributes to the
  diversity of life and whose extinction would lead
  to extinction of other forms of life
• Dramatic shifts in the ecosystem can occur when a
  keystone species is removed

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Keystone species examples

• Sea Stars Starfish
• Sea stars prey on muscles, urchins, and other
  shell fish
• When removed muscle populations explode and out
  compete other organisms
• Sea urchins rise to the point they destroy coral
  reefs

• Sea Otter
• Prey on sea urchins
• Sea urchins eat through kelp holdfasts, which
  anchor the kelp to the ground, causing entire
  kelp forests to float away

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Wolves in Yellowstone

• Homework
• Download the article from my website
• Read and annotate
• paragraphs
• Highlight main ideas
• Write a one paragraph summary