Population
interacting groups of organisms of the same species living in an area
Population
Members of a population normally interbreed with each other and do NOT interbreed with individuals in populations of other species
Random sampling
Taking samples without any bias in order to estimate the size of a population
Random sampling
Any part of the population has equal chance of being included in the sample
Sampling error
The difference between a sample statistic (the estimated population size) and the equivalent value for the whole population (the true size of the population)
Quadrat sampling
Repeatedly placing a quadrat frame at random positions in a habitat and recording the number of organisms present each time
Quadrat sampling
Suitable for plants and other sessile organisms
Carrying capacity
The maximum size of a population that an environment can support
Competition
The struggle between organisms to survive in a habitat with limited resource(s)
Carrying capacity
Often determined by the limitation of one resource (or a small number of resources), therefore impacting population size
Negative feedback control
Allows for the overall population to remain relative stable over time (with fluctuations)
Density-independent factors
Have the same effect however large the size of a population
Density-dependent factors
Have an increasing effect as the population becomes larger
Density-dependent factors
Are the basis for negative feedback mechanisms because they reduce larger populations and allow smaller populations to increase
Competition
Example(s) of a density-dependent factor
Predation
Example(s) of a density-dependent factor
Predation
Becomes more intense if a population of prey becomes more dense (and easier to find)
Infectious disease, parasitism and prey infestation
Example(s) of a density-dependent factor
Sigmoid population growth curve
Displays the population change over a given period of time
Predation
One consumer species killing and eating another consumer species
Pathogenicity
One species living inside another species and causing a disease in the host
Community
All of the interacting organisms in an ecosystem
Community
A group of populations living together in an area and interacting with each other
Ecosystem
A community of organisms and their abiotic environment
Intraspecific relationship
A relationship that exists between individuals of the same species
Example of competition
Light availability in plants
Example of competition
Using nectar to attract pollinators
Example of cooperation
Communal roosting in animals
Example of cooperation
Hunting in groups
Interspecific relationship
Relationships between species in a community
Herbivory
Primary consumers feeding on producers (which may or may not be killed)
Interspecific competition
Two or more species using the same resource, with the amount taken by one species reducing the amount available to the other species
Example of herbivory
Aphids feeding on phloem sap from plants
Example of predation
Starfish eating oysters
Example of interspecific competition
Ivy climbing up oak trees and competing for light
Example of parasitism
Ticks living on deer
Mutualism
Interspecific: close associations between species where both species benefit from the relationship
Species
Organisms that can breed with each other and produce fertile offspring
Species of asexually reproducing organisms
Organisms with highly similar genomes
Reproductive isolation
Cannot breed with each other to produce fertile offspring