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8/2/2019 Life in a Global Context (Part 3)
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Life in a Global Context (Part 3)
What ecological factors place limits on a species geographic range?
Abiotic (physical) Dispersal Biotic Biological interactions Habitat selection
What are abiotic factors?
Climate (temperature, moisture) Soils (minerals, texture, acidity) Geology (rock type, land formations) Light (sun, shade) Nutrients (nitrogen, phosphorus, potassium) Habitat Pollutants
Rain Shadow
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Wallaces Line
A hypothetical line demarcating the distribution of Asian andAustralian fauna, passing between the islands of Bali and Lombok to
the south and Borneo and Sulawesi to the north, used especially in
biogeographic studies of evolution.
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Species Gradient
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Biotas of major biogeographic regions vary strikingly
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How will abiotic factors influence distributions?
Restrict access to resourceso Food/nutrientso Habitat
Limit physical toleranceso Hot/coldo Chemistry (toxins)
Physical barrierso River, mountain, lake, and ocean
How would you determine which abiotic factor is limiting the distribution of an
organism?
Field observation of actual range of distribution Determine ecological tolerances
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Correlation between environmental gradients and a speciesoptimum range
Experiments (field transplant, controlled environment)
Transplant Experiment
Control: transplant within range Treatment: transplant outside range
Transplant: Limit of Tree Line
Timberline decreases 100m for every degree in latitude Wardle transplanted seedlings (all died) Transplanted with shade cloth (survived 180m above tree line) Conclusion: temperature and drought interact to control tree line
Limits to Tree Line
Smith and Germino (2002), physiological ecologists transplantedEngelmann spruce (Picea engelmannii) seedlings above tree line inWyoming
o Treatment: Underneath herbaceous canopy (shaded,
competition for water)
On bare soil (high light, no competition for water)
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On bare soil, surrounded by herbaceous canopy(high light, competition for water)
Approaches to Studying Ecology
Observational approacho Detecting patterns in natureo Quantitative monitoring (LTR/chronology studies)o Correlation Causation
Experimental approacho Design (treatments, controls, replication)o Process know linked to patternso Develop confidence in predictions
Theoretical approacho Theory is based on modelso Statistical model, conceptual model, or simulation modelso
Experimental Approach
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Realism Precision & Control
Global Warming Trends
Keelings Curve
Natural Experiment
Volcano
Large scale
Low cost
Difficult to replicate
Lab Experiment
Greenhouse
Small scale
Medium to low cost
Low variation in
replicates
Field Experiment
Natural forest
Large-small scale
High cost
High variation in replicates
Semi-Field Experiment
Plantation
Small scale
Medium to low cost
Medium to low variation in replicates
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Will global warming impact species distributions and limits?
Alpine tree lines increase 1000m with a 3C/year increase intemperature
Arctic tree line expansion Species replacement (deciduous vs. boreal) Grassland succession into warm dry forest (Douglas fir/Jack Pine) Ecological processes (fire cycles, flooding regimes, landslides) Wetland shrinkage Habitat changes faster than organism dispersal or adaptation
Tropical Cloud Forest
Cloud layer at 1000-3000m above sea level Unique vegetation and animals More epiphytes, pteridophytes, and bryophytes than low valley rain
forest
Temperature drops 6C/1000m
Will global warming influence this ecosystem?