Ecology

The science by which we study how organisms interact in and with the natural world.

A collection of living and non-living components that are tied together by regular interactions

• 1) Organism with its surroundings
• 2) Populations within a habitat
• 3) Community with abiotic environment

• 1) Ecological systems are physical entities
• 2) Ecological systems exchange materials and energy with their surroundings
• 3) Ecological systems undergo evolutionary change

No

Steady states

Ernst Haeckal

Characterizes and explains the statistical patterns of Abundance, Distribution, and Diversity

The range in an environmental gradient in which a species is best suited for growth or reproduction

They have been restricted to one end of it's tolerance range in nature

When a process depends on many different factors, then the process will be limited by the factor in the Lowest Relative Abundance

Silicate or Phospahate limitation

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

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)

4th

• 1) Forested Regions
• 2) Interior Valleys
• 3) Steppe Region
• 4) Coastal Strand

Consume - Inorganic--> Organic

Release- Organic--> Inorganic

Organization of ecosystem into functional units that exchange materials and energy

• -Living Organisms
• -Inorganic pool
• -Organic pool
• -Unavailable pools

Nitrogen Fixing organisms (prokaryotes)

Rate at which nutrients are made available to primary producers is determined largely by rate of mineralization

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

Leaves with a higher lignin content decomposed at a slower rate

Leaves degraded faster in streams with higher nitrate concentrations

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

Invading N-fixing tree Myrica faya is altering N dynamics of Hawaiian ecosystems

A group of populations that occur together, interact, and whose ecological function and dynamics are in some way interdependent

• -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

• -Most numerous
• -Greatest biomass
• -Preempt the most space
• -Largest contribution to energy or nutrient flow
• -Behavior

• -Open/Individualistic Communities
• -Closed/Organismal Communities

Henry Gleason

• -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

• -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

• -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

The total number of species in a community or region

• 1) Species richness
• 2) Relative abundance (species evenness)

A quantitative measure of relative diversity

Species Richness

Statistical method to compare species richness for unequal sample sizes

• -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

The majority of communities studied by ecologists display a log normal pattern of species abundance

• -Based on dominance of species
• -Emphasizes evenness

• -Rare species are mostly ignored
• -Influenced by sample size

The probability that any two individuals drawn randomly from a population belong to different species

Portray relative abundance and species diversity within a community by plotting relative abundance of species against their rank in abundance

• 1) Alpha local
• 2) Beta regional
• 3) Gamma biogeographical

Diversity of small areas of relatively homogeneous habitat; number of species per unit area

Describe local community structure

Change in species composition over relatively small distances; often between distinct adjacent habitats along an environmental gradient

Describe species turnover

Diversity of similar habitat type separated by wide geographic distances

Address the relative roles that history and ecology have played in species assemblages, distribution

Increases

Decreases

Decreases

• 1) Environmental Heterogeneity
• 2) Area
• 3) Climatic Stability
• 4) Biotic factors
• 5) Evolutionary speed