Population

Population – number of individuals of a single species in a specific area
Density – number of individuals per unit area
Population density declines with increasing organism size
Abundance – total number of individuals or biomass of a population

Distribution – size, shape, and location of a population
Random distribution- individuals have an equal chance living anywhere within the area
Based on neutral interactions
Regular distribution – individuals are uniformly place throughout the area
Based on antagonistic interactions
Clumped distribution – individuals have a much higher probability of being found in some areas than in others.
Based on attractive interactions
Reasons for distribution patterns:
 Competition between species or individuals
 Reproduction (genetic drift) and survivability
 Availability of food (prey or light)
 Defense Mechanisms of neighboring species or individuals

Small scale – distance of no more than a few hundred meters
Large scale – cover distances greater than a few hundred meters and has substantial environmental change

Ways to characterize a species:
 Population
 Density
 Age Distribution
 Birth / Death rates
 Immigration / Emigration
 Rates of Growth
 Distribution
 Abundance

Main Points:
O small scale, individuals within a population are distributed in patterns that may be random, regular, or clumped,
On larger scale, individuals within a population are clumped.
Population density declines with increasing organism size.

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