Spatial Population Structure Flashcards
Scaling
The spatial extent of ecological processes and the spatial interpretation of the data. Response of an organism to the environment is particular to a specific scale
Spatial distribution of populations is limited by
niche to ecologically suitable. measured as the n-dimensional hypervolume of environmental conditions in which a population has positive growth (The range of habitats where population perform well)
Competitive Exclusion
Species with the same niche cannot coexist indefinitely.
Fundamental Niche
Range of abiotic factors in which a species can exist
Realized Niche
Range biotic and abiotic factors in which a species can exist
A measure of the total area covered by a species reflects its
realized niche
A realized niche is limited by
abiotic conditions, habitat availability, species interaction (competition, natural enemies)
Suitable climate conditions for species known as
climatic envelope
Habitat availability
Some areas wont be occupied
Abundance
Total number of individuals in a population that exist in a defined area
Population Density
The number of individuals per unit area or volume. Typically higher near center of geographic range
Census
Count all (only small populations)
Area/Volume-Based Surveys
Sample and extrapolate ~density
Capture-mark recapture (CMR
-The estimate abundance (N)
-Capture and mark a number of animals (=M) from the study population
-Release back into population
N=n (total individuals captured second sample) times M (initially captured individuals) /x (marked recaptured individuals)
Surveying
Quadrets/line transects
-calculate mean density across quadrats/lines
-unbiased placement
-more quadrats/lines=more precision
Assumptions of CMP
-Animal marking are not lost, marked and unmarked -Animals are equally likely to be caught. They mix thoroughly between the samples
-No change in population size across sampling periods (no deaths, births, emigration, or immigration)
-Sometimes, natural markings can be used
Clustered species
> 1 Clustered resources. Social behavior. Limited dispersal
Evenly spaced species. Uniform, regular.
<1 Depleted resources. Aggressive social interactions. Competition, territioriality
Random
~1
-Expected without any deterministic processes
-Not common in nature
-A null model for the dispersion of organisms
-position of each organism is independent of others
Dispersal
Movement of individuals from one area to another not related to back and forth migrations. Can lead to colonization of new areas. Dispersal limitation can constrain geographic ranges.
Endemic
Found there and only there. The double coconut is endemic to Seychelles. Dandelions found on all continents except for antarctica (not endemic)
Population Structure
Subdivision of organisms into subpopulations living in suitable patches of habitat surrounded by matrix
Matrix
Unsuitable habitat
Metapopulation
Set of populations or sub populations of a species, linked by dispersal.
Basic Metapopulation Model
Suitable habitat patches (equal quality) embedded within a matrix of unsuitable habitat. Proportion of patches occupied reflects colonization and extinction rates
Sources
High quality habitat and positive population growth without emigration. Self sustaining and provides dispersers.
Sinks
Poor quality habitat and negative population growth without immigration. Rely on dispersers
Landscape Model
Incorporates variation in matrix quality and habitat conductivity. More realistic
Ideal Free Distribution
Individuals distribute among different habitats so that they have the same per capita benefit in proportion to resources
