Ecological Impacts of Global Climate Change

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Ecological Impacts of Global Climate Change
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What exactly is Ecology?

• The study of the interaction between an organism
  and its environment.
• Includes all abiotic and biotic aspects of the
  environment.
• The study of the distribution and abundance of
  organisms.
• Ultimately, the organism-environment interaction
  determines the distribution and abundance of
  species.

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Some Determining Factors of Distribution and
Abundance

• Individual Physiology Abiotic requirements and
  tolerance ranges for a species.
• Population Dynamics Requirements for sustaining
  a population of some limited size.
• Interspecific Interactions Prey / forage
  species needs, competition with similar species,
  pressure from predators.
• Ecosystem Dynamics Energy / nutrient cycling,
  disturbance regimes / stability, etc.

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• Individual Physiology Abiotic requirements,
  tolerance range, etc.
• Temperature tolerance / requirements
• Moisture tolerance / requirements
• Nutrient availability, habitat type, etc.
• Easy to imagine that changes in global
  temperature, precipitation regimes would lead to
  impacts on this level.

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Some Determining Factors of Distribution and
Abundance

• Individual Physiology
• Population Dynamics
• Interspecific Interactions
• Ecosystem DynamicsImpacts anywhere in the chain
  can affect other levels.

Exogenous climate forcing
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Predictable responsesRange shifts due to
climate change

• Changes in geographic temperature / precipitation
  patterns leading to shifts in species
  distributions.
• Pole-ward and higher-elevation shifts
• Reduction / loss of polar habitats and range
  reductions in resident species.
• Changes in precipitation / evapotranspiration
  rates affecting wetland or desert habitats.

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Some Observed Changes

• Shrubs invading arctic tundra ecosystems (North
  America, Russia)
• Extinction of populations of mountain pika (a
  very heat-sensitive species) in western U.S.
• In U.K., 23 of 24 species of dragonflies expanded
  range northward (average 88 km).

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Cod
Anglerfish
Snake blenny
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Predictable changesTiming of seasonal
population dynamics

• Changes in seasonal cycles affecting migration,
  breeding, etc. and other aspects of population
  dynamics
• Timing of breeding affected in temperate / boreal
  habitats (i.e., areas with distinct seasonal
  climate).
• Timing of migrations changed where seasonal cues
  are important.

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Observations

• Earlier dates of amphibian breeding (2-3 weeks,
  U.S., U.K.)
• Earlier bird nesting dates ( 8 days, U.K., North
  America)
• Earlier butterfly appearance dates (20-30 days,
  U.S., U.K.)
• Earlier passage dates of North Sea migrant
  seabirds

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Importance of Synchrony Great Tits and Oak
Caterpillars
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• Great tit nesting dates are historically timed to
  coincide with the peak in abundance of oak
  caterpillars (2-3 week period), which provide
  ample food for nestlings.

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Mismatch in Responses to Recent Warming

• Date of peak caterpillar abundance occurs
  approximately 10-15 days earlier

• Great tit nesting dates have not changed
  significantly.

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Why the Mismatch?

• In years past, earlier caterpillar abundance
  coincided with earlier great tit nesting.
• A 1-day advance in abundance elicited a roughly
  0.3 day advance in nesting date.
• The cues for caterpillar emergence and great tit
  nesting are different.
• Caterpillar emergence linked to oak budding (more
  temp. sensitive species)
• Birds respond to larch and birch budding (less
  temperature sensitive)

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Will the Birds Catch Up?

• Model predictions suggest not. Nesting dates
  will change, but will not re-establish synchrony
  in the near future.
• Consequences of mismatch?
• Documented Lower average chick weight.
• Hypothesized Reduced post-fledging survival,
  selection for reduced brood size.

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More complex interactions

• Changes in environment species ranges can
  affect interactions between multiple species.
• Change outcomes of competition between species.
• Increasing competition between species by
  creating new areas of overlap.
• Interesting example
• Pacific walrus, clams, seals, and the importance
  of sea ice

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Walrus depend on ice for transport to new clam
feeding grounds sea ice extent limits walrus
distribution. Clams primary walrus prey, depend
on sea ice for food Seals As competition for
clams increases, walrus predation on seals
becomes more frequent (documented 5x increase)
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Conclusions

• There is ample evidence that recent climate
  change has impacted the ecology of biota in
  predictable ways.
• This is not new. In part, we know what to look
  for because weve seen this before.
• Its not all doom and gloom now
• but its a complex world. Uncertainty and
  surprises are the rule when predicting ecological
  outcomes.