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The science by which we study how organisms interact in and with the natural world.
Define Ecological System
A collection of living and non-living components that are tied together by regular interactions
What are the 3 levels of organization in an Ecological System
- 1) Organism with its surroundings
- 2) Populations within a habitat
- 3) Community with abiotic environment
What are the 3 principles of an Ecological System?
- 1) Ecological systems are physical entities
- 2) Ecological systems exchange materials and energy with their surroundings
- 3) Ecological systems undergo evolutionary change
Can biological systems alter physical or chemical properties?
Do ecological systems exist in steady or un-steady states?
Who is the founding father of ecology as a science?
What does Macroecology do?
Characterizes and explains the statistical patterns of Abundance, Distribution, and Diversity
Define Optimal Range
The range in an environmental gradient in which a species is best suited for growth or reproduction
What does it mean when sheep sorrel get pushed out of the soil pH where they grow the best and grow in acidic soils?
They have been restricted to one end of it's tolerance range in nature
Define the Law of Minimum
When a process depends on many different factors, then the process will be limited by the factor in the Lowest Relative Abundance
What is Diatom growth regulated by?
Silicate or Phospahate limitation
What is Synergy?
Interaction greater than sum
A reversible physiological or structural change in response to a changing environment
A genetically determined charactersistic that enhances the ability of an organism to cope with it's environment
Define the Law of Trade-Offs
Adaptatioin to one environment makes it difficult or impossible to live in a different environment
Different populations of a species that have genetic differences of ecological significance (color, size, physiology)
What rank is Oregon in species diversity?
What are the Biotic regions in Oregon?
- 1) Forested Regions
- 2) Interior Valleys
- 3) Steppe Region
- 4) Coastal Strand
Do Assimilatory processes consume or release energy?
Consume - Inorganic--> Organic
Do Dissimilatory processes consume or release energy?
Release- Organic--> Inorganic
Define Compartment Models
Organization of ecosystem into functional units that exchange materials and energy
What are some examples of compartment models?
- -Living Organisms
- -Inorganic pool
- -Organic pool
- -Unavailable pools
What can use atmospheric supply directly?
Nitrogen Fixing organisms (prokaryotes)
Define Rates of Decomposition
Rate at which nutrients are made available to primary producers is determined largely by rate of mineralization
Gallardo and Merino found
Differences in mass loss by the target species reflected differences in the physical and chemical characteristics of their leaves
Litter bags to study decomposition in temperate forests
Gessner and Chauvet found that
Leaves with a higher lignin content decomposed at a slower rate
Suberkropp and Chauvet found that
Leaves degraded faster in streams with higher nitrate concentrations
Webster found that
Nutrients in streams are subject to downstream transport
A positive relationship between grazing intensity and rate of turnover in plant biomass in Serengeti Plain
Nutrient dynamics under canopy of native shrub and introduced acacia
Vitousek and Walker found
Invading N-fixing tree Myrica faya is altering N dynamics of Hawaiian ecosystems
Define Ecological Community
A group of populations that occur together, interact, and whose ecological function and dynamics are in some way interdependent
Ecological communities can be characterized by
- -Dominant species
- -Major growth habit
- -Geographic location
- -Climate type
- -Major taxon
- -Trophic level
The organization of the community in vertical space
Horizontal changes in the physical environment reflect zonational changes in plant and animal components of ecological communities
A group of species thatexploit the same environmental resources in a similar way
In what ways could an organism be dominant in the ecological community?
- -Most numerous
- -Greatest biomass
- -Preempt the most space
- -Largest contribution to energy or nutrient flow
What are the two fundamentally different models for why certain species occur together?
- -Open/Individualistic Communities
- -Closed/Organismal Communities
Who was the main proponent of Open communities?
Describe characteristics of an Open community
- -Species are individualistic
- -Occurrence of one species is independent of other species
- -Each species has a characteristic environmental tolerance or optimal range
- -Species occur together where environmental tolerance coincide
- -Overlapping species populations intergrade
- -Communities are a gradient or continuum of species associations accross a changing physical environment
Describe characteristics of a closed community
- -Main proponent was Frederic Clements
- -Communities are discrete, discontinuous, predictable entities
- -Community types are compared to "super organisms"
- -Certain clusters of species reach their optima in the same environmental conditions
- -Dominant members of one group do not occur as important or dominant members of any other group
- -Only minor overlap between communities
What is the Intermediate Disturbance Hypothesis?
- -Species diversity is low when frequency or intensity of disturbance is high
- -Species diversity is low when frequency or intensity of disturbance is low
- Greatest species diversity occurs when frequency or intensity of disturbance is intermediate
Define Species Diversity
The total number of species in a community or region
What are the 2 components of diversity?
- 1) Species richness
- 2) Relative abundance (species evenness)
Define Diversity Index
A quantitative measure of relative diversity
What is the simplest and most common measure of diversity?
Statistical method to compare species richness for unequal sample sizes
What should be known about rarefaction
- -Can be used to compare species richness for unequal sample sizes
- -Uses number of species and relative abundance to estimate expected number of species in a standard sample size
- -Some information is lost, number of species and relative abundance is converted to expected number of species only
Describe Lognormal Distribution
The majority of communities studied by ecologists display a log normal pattern of species abundance
Describe Simpson's Index
- -Based on dominance of species
- -Emphasizes evenness
What are the disadvantages of Simpson's Index?
- -Rare species are mostly ignored
- -Influenced by sample size
Define Simpson's Index
The probability that any two individuals drawn randomly from a population belong to different species
What do Rank Abundance Curves do?
Portray relative abundance and species diversity within a community by plotting relative abundance of species against their rank in abundance
What are the 3 terms used to divide spatial scale continuum?
- 1) Alpha local
- 2) Beta regional
- 3) Gamma biogeographical
Define Alpha diversity
Diversity of small areas of relatively homogeneous habitat; number of species per unit area
What is the principal goal of Alpha diversity?
Describe local community structure
Define Beta Diversity
Change in species composition over relatively small distances; often between distinct adjacent habitats along an environmental gradient
What is the principal goal of Beta Diversity?
Describe species turnover
Define Gamma Diversity
Diversity of similar habitat type separated by wide geographic distances
What is the principal goal of Gamma Diversity?
Address the relative roles that history and ecology have played in species assemblages, distribution
In latitudinal diversity gradients, species diversity (Increases/Decreases) with decreasing lattitude
In elevational diversity gradients, diversity (Increases/Decreases) with increasing elevation
In Aridity diversity gradiants, diversity (Increases/Decreases) with increasing aridity
What are the 2 factors controlling diversity?
- 1) Environmental Heterogeneity
- 2) Area
- 3) Climatic Stability
- 4) Biotic factors
- 5) Evolutionary speed