View
226
Download
4
Category
Tags:
Preview:
Citation preview
Chapter #16 – Community Structure(pg. 334 – 348)
Chapter #16 – Community Structure(pg. 334 – 348)
16.1 – The Number of Species and Their Relative Abundance Define Diversity.
16.2 – Numerical Supremacy Defines Dominance.
16.3 – Keystone Species Have an Influence on Community Structure Disproportionate to Their Numbers.
16.4 – Food Webs Describe Species Interactions.
16.5 – Species Within a Community Can Be Classified into Functional Groups.
16.6 – Communities Have a Definitive Physical Structure.
16.7 – Zonation is Spatial Change in Community Structure.
16.8 – Defining Boundaries Between Communities Is Often Difficult.
16.9 – Two Contrasting Views of the Community.
Individual to IndividualTerritory, Home Range, DensityAbundance, Distribution
Species to SpeciesPredator-PreyCompete (?) for access to essential resources
Species to Abiotic (non-living) ComponentsSoil, Topography, Weather
Species A Species B
Species C Species D
Ecological “Lines of Dependency”
Chapter #16 – Community Structure(pg. 334 – 348)
The group of species that occupy a given area, interaction either directly or indirectly is called a community.
Chapter #16 – Community Structure(pg. 334 – 348)
16.1 – The Number of Species and Their Relative Abundance Define Diversity.
Perhaps the simplest and easiest measure of community structure is a count of the number of species that occur within the community: species richness.
The percentage or rankabundance of the species in a community is called RelativeAbundance.
Chapter #16 – Community Structure(pg. 334 – 348)
16.1 – The Number of Species and Their Relative Abundance Define Diversity.
Chapter #16 – Community Structure(pg. 334 – 348)
16.1 – The Number of Species and Their Relative Abundance Define Diversity.
Simpson’s Index (D)
measures the diversity and dominance of species in a community.
16.2 – Numerical Supremacy Defines Dominance.
Chapter #16 – Community Structure(pg. 334 – 348)
When a single or few
species predominate
within a community,
these organisms
are referred to as
dominants.
Chapter #16 – Community Structure(pg. 334 – 348)
16.3 – Keystone Species Have an Influence on Community Structure Disproportionate to Their Numbers.
A species that has a disproportionate impact/effect on the community relative to its abundance is referred to as a keystone species.
Chapter #16 – Community Structure(pg. 334 – 348)
16.3 – Keystone Species Have an Influence on Community Structure Disproportionate to Their Numbers.
Creel, S. 2005. Elk Alter Habitat Selection as an Antipredator Response to Wolves. Ecology 86(12):3387-3397.
Chapter #16 – Community Structure(pg. 334 – 348)
16.4 – Food Webs Describe Species Interactions.
Each circle represents a species, each line represents a
“link”, or connection to another species.
A – Autotrophs, H – Herbivores, C – Carnivores, P - Predator
Chapter #16 – Community Structure(pg. 334 – 348)
16.5 – Species Within a Community Can Be Classified into Functional Groups.
Guilds: another approach to grouping organisms that derive their food energy in a similar manner. As defined, guilds typically represent strong species interactions.
Chapter #16 – Community Structure(pg. 334 – 348)
16.6 – Communities Have a Definitive Physical Structure.
Factors: in terrestrial communities, vegetation is the principle factor governing community structure. In aquatic communities, vegetation and the physical nature of the water (depth, temperature, flow rate, salinity, pH, light availability) are used to define the community.
Chapter #16 – Community Structure(pg. 334 – 348)
16.7 – Zonation Is Spatial Change in Community Structure.
Zonation: the changes in the physical and biological structures of communities as one moves across the landscape. Zonation also involves changes associated with scale.
Chapter #16 – Community Structure(pg. 334 – 348)
16.7 – Zonation Is Spatial Change in Community Structure.
Chapter #16 – Community Structure(pg. 334 – 348)
16.7 – Zonation Is Spatial Change in Community Structure.
Chapter #16 – Community Structure(pg. 334 – 348)
16.8 – Defining Boundaries Between Communities Is Often Difficult.
Chapter #16 – Community Structure(pg. 334 – 348)
16.9 – Two Contrasting Views of the Community.
Frederic Clements The Organismic concept of communities
Species similar evolutionary and climatic histories.
“Succession”
Chapter #16 – Community Structure(pg. 334 – 348)
16.9 – Two Contrasting Views of the Community.
H. A. Gleason The Individualistic concept of communities
Species similarities in their tolerances and requirements,
not evolutionary history. “Gradual Change”
– The Ecological Niche Defines the Place and Role of Each Species in Its Ecosystem
– Adaptations Reduce the Overlap of Ecological Niches Among Coexisting Species
– Helps Control Population Size and Distribution
Chapter #16 – Community Structure(pg. 334 – 348)
Ecological Niche (fundamental and realized)The total
requirements of a species for all resources and
physical conditions determine where it can live and how
abundant it can be at any one place within its range.
Chapter #16 – Community Structure(pg. 334 – 348)
• Encompasses all aspects of a species’ way of life, including
– Physical home or habitat.– Physical and chemical environmental
factors necessary for survival.– How the species acquires its energy
and materials.– All the other species with which it
interacts.
Ecological Niche
Chapter #16 – Community Structure(pg. 334 – 348)
Resource Partitioning – CoexistenceGause's Principle: no two species
can coexist on the same limiting resource.Species avoid competitionby partitioningresources andhabitats amongthemselves.
Chapter #16 – Community Structure(pg. 334 – 348)
Chapter #16 – Community Structure(pg. 334 – 348)
Resource Partitioning
Desiccates atlow tide.
Does not desiccateat high tide
Competition
• When species withlargely overlappingniches are allowedto compete, theirniches may focuson a different part ofthe resource spectrum.
– Example: North American Warbler Species.
Reducing Niche Overlap
Chapter #16 – Community Structure(pg. 334 – 348)
Species – Area Curve
In general, the larger the area, the greater the
number of species.
Chapter #16 – Community Structure(pg. 334 – 348)
Recommended