Download 04 Climate Change LO.10

ECOLOGICAL RESPONSES TO CLIMATE CHANGE
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OBJECTIVES
1) What aspects of individual organisms does temperature (T) affect?
What level of biological organization of the individual does T affect?
2) Why are individuals so sensitive to minor changes in T?
3) What are general types of organismal (individual) responses to a changing environment?
4) What types of responses to T change occur at each of six levels of ecological organization
(individual through global)?
A) If no migration B) If migration
5) What are specific examples of responses at each level?
6) How is T change affecting humans?
LEARN MAJOR CONCEPTS
1) Temperature affects molecular, physiological, and whole organism levels.
2) (Enzymes of) Most species perform best in a fairly narrow range of temperatures.
3) The phenotype, the expression of the in the form and function of the individual organism,
results from both genetic and environmental influences. If the environment changes, then the
phenotype may change.
4) General responses of organisms to a changing environment include:
A) acclimation, a non-genetic, reversible change in form/function to better match a
new environment
B) adaptation, the evolutionary process by which organisms become better suited to
their (changing) environment
C) migration to enable organisms to survive extreme changes in the environment
5) Responses to T change arise at all levels of ecological organization and have different
ramifications:
(Individual, population, species interactions, community, ecosystem, global) 1.1
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I. INDIVIDUAL ORGANISM’S RESPONSES TO T CHANGE
Why is an increase in temperature important to an organism?
What aspects of individual organism does T affect?
1) molecular level via enzyme conformation and function
2) physiological function (e.g. photosynthetic rate; metabolic rate; microbial respiration
3a) whole organism
Most organisms have evolved ways to compensate for variation in environmental
temperature by regulating body T e.g. endotherms – adjust metabolic rate
ectotherms – adjust morphology/behavior
energy requirements of thermoregulation may influence distribution of species
3b) temperature as cue for phenology (seasonal activities)
e.g. bud break, leaf expansion, seed germination, reproduction,
break dormancy, hibernation, diapause
Most species perform best in a fairly narrow range of T (optimal range)
Extreme temps impair enzyme function and lower rates of chemical reactions
II. ECOLOGICAL RESPONSES TO T CHANGE
A. If no migration and
1 .If no adjustments  individual may not survive
2.If adjust via phenotypic plasticity
Phenotype = Genetic + Environment; if change environ., then change phenotype.
Individual: acclimation: a non-genetic, reversible change in form/function to better
match a new environment
1) Change in life history event, e.g. when develop, reproduction, enter dormancy
2) Change in phenology (time of activity) and growing season
3) Change in births e.g. # babies, # breeding cycles/yr or whether reproduce
4) Change in survival
Population:
1) change in population size due to decreased birth rate or increased death rate
2) extinction
If adjust by evolution
3) adaptation via natural selection (assumes trait is heritable)
Must have pre-adaptation; genetic variation doesn’t arise from necessity.
Select appropriate genotypes for change in temperature
How rapid evolve?
Do rates of environmental vs. evolutionary change differ?
How does length of life cycle and population size affect speed and
probability of adaptation and persistence?
Small animals with short life cycles/large pop siz better able to adapt
and persist than large animals  decrease in pop size or replaced
Species Interactions: On what does persistence depend?
May need parallel (synchronous) changes between interacting species
Community: Change in species composition and relative abundance of species
Ecosystem:
1) productivity (amount of carbon fixed; drives available energy)
2) increase in rate of processes within nutrient cycles (e.g. microbial decomposition)
Global: change in phenology, growing season, PS and respiration leads to:
change in carbon cycle – time of seasonal decrease/increase in CO2 changes
B. If adjust via migration (phenotypic plasticity of behavior)
1. Which groups can migrate? By what means?
If sessile – use spores, seeds, larvae to move
If mobile – use flight or no flight
2. Which groups can migrate fast enough?
Time lag in response to change in T
3. Historically: what was speed after glaciers retreated?
4. Present:
a) Change in latitude
Range expansion (S stays same; N expands)
Range shift (move out of S; move into N)
What differs now that will impede and/or slow migration? landscape fragmentation
b) Change in altitude
Consequences of move at multiple levels of ecological organization
Individual: move or not; may die if doesn’t move
Population: some individuals move; others don’t 
change in genotype frequency (=evolution)
Some ind. move fast and survive  select for strong dispersal ability
Some can’t move; no suitable habitat to move to
e.g. if in N already or on top of mountain  extinction
Species Interactions: what if non-parallel (asynchronous) moves between species?
1. alters competition; may change to new invading competitor
2. alters predator-prey relations; e.g. prey may lose or gain predator control
3. alters mutualism; e.g. pollinator/seed disperser may be lost
Community: Do whole biomes move together?
Or does each species move at different speed/direction?
Changes in:
1) species composition
2) relative abundance of species
5. What are conservation problems with migration?
Boundaries of conserved areas may need to be changed; habitats shifting
Increase in number of species needing conservation
III. Consequences of T change for humans
1) acclimate physiology
2) increase in water evaporation, decrease snowfall, ice fields and glaciers, and increase
drought 
3) less water available to drink and for irrigation
4) lower food production (no pollination; less yield from heat and water stress)
5) increase health problems
increase diarrhea (bacteria thrive in increased temperatures)
increase in infectious diseases
malaria, dengue fever, yellow fever; mosquitoes changing range; moving up mts.
new emerging diseases (West Nile)
pandemics possible