Topic 9 -Spatial Population Distribution Flashcards
Population
A group of individuals of the same species living together
Population ecology
Are the processes of birth, death, migration that influence the abundance and distribution patterns of groups of organisms
Population structure is characterized by
Spatial structure
age/size structure
genetic structure
Spatial structure
How individuals organize themselves in space:
geographic distribution/range patterns of dispersal
patterns of dispersion
population size
Age/size structure
Number of individuals in each age/size class
Demographic rates (birth, death, migration) of individuals change throughout their lifetime
Genetic structure
Genetic composition of all individuals combined within the population
Geographical distribution range
Geographical area in which a species occurs
Determined by presence of suitable environmental conditions and resources
Habitat patch
An area of homogeneous environmental conditions
Contain suitable conditions and resources needed to sustain a population
Habitat patches can be heterogeneously distributed over the range separated by unsuitable habitat which results in many
Local populations Of species within a range (sub populations)
Meta populations
the collective of all subpopulations
Ecology typically occurs at the level of the________rather than the entire population over its entire geographic range
Sub population
Movement of individuals in space is referred to as
Dispersal
Movement of individuals among the sub populations is key to the dynamics of
Metapopulations
With animals dispersal is active but many use passive means like
Wind and water
Wind carries the young of spiders and moths
Larval forms of many invertebrates or carry down stream by currents
Plants tend to move at the level of speed
Dispersal of seeds involves
Gravity, wind, water and animals
Plants have adaptations designed for increased dispersal such as
Release of fluid pressure allows some plants to physically eject seeds a considerable distance
Buoyancy allows fruit/seeds to be carried away by water
Other plants use sugar rewards to attract herbivores, incentive to consume the fruit and transport seeds to another location
Fruits and seeds armed with hooks and spines to catch on the fur of animals
Dispersal
Movement of individuals away from a place of birth or areas of high population density
Immigration
Movement of individuals into a population
Emigration
Movement of individuals out of a population
The degree of interaction among local populations depends on
Ability of individuals to disperse between habitat patches:
Distance between, suitability of environment
Habitat patch size and quality:
Larger/higher quality patches tend to support more individuals
Patterns of dispersion
Random
uniform
clumped
Random dispersion
Individuals have no influence on each other
resources are randomly scattered across the Range
Uniform dispersion
Individuals engage in negative interactions such as intense competition for space
Individual space themselves evenly to minimize interactions
Clumped dispersion
Most common type of distribution where individuals form groups or clusters
patchy resource distribution or environmental conditions
Social tendencies
cloning
types of individuals that can make a population
Unitary individuals
modular individuals
Modular individuals
Consist of many interconnected units derived from the same zygote example plants
Modular individuals can exist separately and be physiologically Independent
Unitary individuals
Physically and genetically distinct individuals each arising from a genetically distinct zygote example humans
Genets
Genetically distinct individuals each derived from a single zygote (sexual reproduction)
Ramets
Modules with the potential to exist separately (genetically identical, asexual reproduction)
Conservation
If a population of ramets, They will have no genetic variation and be less likely to adapt to environmental changes resulting in a high risk of extinction
Accurate estimates to count populations combine
Geographical range
patterns of dispersal
Local density equals
Number of individuals per unit area
Methods of estimation
Quadrat sampling
Line transects
Mark-recapture
Quadrat sampling
Count individuals contained in a fraction of an area
Best on immobile organisms
Line transects
Measure distance to observe specimens while walking a straight line
Use of formulas to estimate population size
Mark-recapture
Create an identifiable mark on all specimens captured in first sample
Sample again an estimate population size based on the proportion recapture
