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Population Ecology Populations are groups of potentially reproducing individuals in the same place , at the same time , that share a common gene pool . I. Spatial Distributions A. Dispersion. I. Spatial Distributions A. Dispersion - Regular. I. Spatial Distributions
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Population Ecology Populations are groups of potentially reproducing individuals in the same place, at the same time, that share a common gene pool. I. Spatial Distributions A. Dispersion
I. Spatial Distributions A. Dispersion - Regular
I. Spatial Distributions A. Dispersion - Regular - intraspecific competition - allelopathy - territoriality
I. Spatial Distributions A. Dispersion - Clumped - patchy resource - social effects
I. Spatial Distributions A. Dispersion - Random - canopy trees, later in succession
I. Spatial Distributions A. Dispersion - Complexities - can change with development. Seedlings are often clumped (around parent or in a gap), but randomness develops as correlations among resources decline. regular can develop if competition becomes limiting.
I. Spatial Distributions A. Dispersion - Complexities - can change with development. Seedlings are often clumped (around parent or in a gap), but randomness develops as correlations among resources decline. regular can develop if competition becomes limiting. - can change with population, depending on resource distribution.
I. Spatial Distributions A. Dispersion - Complexities - can change with development. Seedlings are often clumped (around parent or in a gap), but randomness develops as correlations among resources decline. regular can develop if competition becomes limiting. - can change with population, depending on resource distribution. - varies with scale. As scale increases, the environment will appear more 'patchy' and individuals will look clumped.
II. COMPETITION B. Modeling Competition 1. Intraspecific competition
II. COMPETITION B. Modeling Competition 2. Interspecific competition The effect of 10 individuals of species 2 on species 1, in terms of 1, requires a "conversion term" called a competition coefficient (α).
II. COMPETITION A. Modeling Competition B. Empirical Tests of Competition
B. Empirical Tests of Competition 1. Gauss P. aurelia vs. P. caudatum P. aurelia outcompetes P. caudatum.
B. Empirical Tests of Competition 1. Gauss P. aurelia vs. P. bursaria ):
B. Empirical Tests of Competition 1. Gauss P. aurelia vs. P. bursaria: coexistence ):
B. Empirical Tests of Competition 1. Gauss Why do the outcomes differ? - P. aurelia and P. caudatum feed on suspended bacteria - they feed in the same microhabitat on the same things. P. bursaria feeds on bacteria adhering to the glass of the culture flasks. ):
B. Empirical Tests of Competition 1. Gauss Why do the outcomes differ? - P. aurelia and P. caudatum feed on suspended bacteria - they feed in the same microhabitat on the same things. P. bursaria feeds on bacteria adhering to the glass of the culture flasks. - Gauss concluded that two species using the environment in the same way (same niche) could not coexist. This is the competitive exclusion principle. ):
B. Empirical Tests of Competition 1. Gauss 2. Park • Competition between two species of flour beetle: Tribolium castaneum and T. confusum. Tribolium castaneum
B. Empirical Tests of Competition 1. Gauss 2. Park Competitive outcomes are dependent on complex environmental conditions Basically, T. confusum wins when it's dry, regardless of temp.
B. Empirical Tests of Competition 1. Gauss 2. Park Competitive outcomes are dependent on complex environmental conditions But when it's moist, outcome depends on temperature
B. Empirical Tests of Competition 1. Gauss 2. Park 3. Connell ): Intertidal organisms show a zonation pattern... those that can tolerate more desiccation occur higher in the intertidal.
3. Connell - reciprocal transplant experiments Fundamental Niches defined by physiological tolerances ): increasing desiccation stress
3. Connell - reciprocal transplant experiments Realized Niches defined by competition ): Balanus competitively excludes Chthamalus from the "best" habitat, and limits it to more stressful habitat
II. COMPETITION A. Modeling Competition B. Empirical Tests of Competition C. Competitive Outcomes: - Reduction in organism growth and/or pop. size (G, M, R) - Competitive exclusion (N = 0) - Reduce range of resources used = resource partitioning. - If this selective pressure continues, it may result in a morphological change in the competition. This adaptive response to competition is called Character Displacement ):
III. Predation A. Predators can limit the growth of prey populations
Moose and Wolves - Isle Royale 1930's - Moose population about 2400 on Isle Royale
1930's - Moose population about 2400 on Isle Royale 1949 - Wolves cross on an ice bridge; studied since 1958
1930's - Moose population about 2400 on Isle Royale 1949 - Wolves cross on an ice bridge; studied since 1958
V. Dynamics of Consumer-Resource Interactions A. Predators can limit the growth of prey populations B. Oscillations are a Common Pattern
IV. Mutualism Trophic Mutualisms – help one another get nutrients
Trophic Mutualisms – help one another get nutrients 1-Esophagus2-Stomach3-Small Intestine4-Cecum (large intestine) - F5-Colon (large intestine)6-Rectum Low efficiency - high throughput...
Defensive Mutualisms – Trade protection for food Acacia and Acacia ants
Dispersive Mutualisms – Trade dispersal for food Create floral ‘syndromes’ – suites of characteristics that predispose use by one type of disperser
Dispersive Mutualisms – Trade dispersal for food Not mutualism (commensal or parasitic)