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