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Concept 8.1: Populations are dynamic entities that vary
in size over time and space.
Concept 8.2: The distributions and abundances of organisms are limited by
habitat suitability, historical factors, and dispersal.
Concept 8.3: Many species have a -------------of populations across their geographic range.
Concept 8.4: The dispersion of individuals within a population depends on the (3 things)
location of essential resources, dispersal, and behavioral interactions.
Geographic area over which individuals of a species occur.
The number of individuals in a specific area
Ecologists often wish to understand what factors determine the -------------and ------------- of species.
distribution and abundance
The total weight of individuals in a specific area
Number of individuals per unit area (land) or volume (density)
Mark recapture experiments
M/N=m/n what do letters stand for?
- M = number of marked individuals released
- N = actual size of population
- m = number of marked individuals captured the 2nd time
- n = the total number of individuals 2nd time
Distribution – can have 2 definitions 1
- 1The geographic range of an organism
- (Determined on the MACRO scale usually by abiotic factors)
Distribution – can have 2 definitions 2
2The spatial arrangement of individuals in a local population (Determined on the MICRO scale, usually by both abiotic and biotic factors)
Abundance can be reported as -------- or -----------
population size (# individuals), or density (# individuals per unit area).
Individuals can be defined as
products of a single fertilization: The aspen grove would be one individual, a genet.
Members of a genet may be independent physiologically, so members of a genet are called --------
Abiotic features of the environment include (5)
moisture, temperature, pH, sunlight, nutrients, etc.
events that kill or damage some individuals, creating opportunities for other individuals to grow and reproduce.
Individuals are uniformly spaced through the environment Cause? (2)
- 1Antagonistic interactions between individuals
- 2Local depletion of resources
An individual has an equal probability of occurring anywhere in an area Cause?(2)
- 1Neutral interactions between individuals and the environment
- 2Neutral interactions between individuals
Individuals live in areas of high local abundance separated by areas of low abundance Cause? (2)
- 1Attraction between individuals
- 2Attraction of individuals to a common resource
Dispersion is the
spatial arrangement of individuals within a population:
Dispersion types (3)
- 1Regular (uniform)—individuals are evenly spaced.
- 2Random—individuals scattered randomly.
- 3Clumped (aggregated)—the most common pattern
The ecological niche:
The physical and biological conditions that a species needs to grow, survive, and reproduce.
A niche model is a
predictive tool that models the environmental conditions occupied by a species based on the conditions at localities it is known to occupy.