Consumption two species competing to eat the same

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Consumption : two species competing to eat the same food resource or use the same space to take up water, nutrients or sunlight Pre-emption : one species is able to access or utilize a resource more quickly Overgrowth : one species uses greater biomass to “stifle” a smaller species o Interference : species directly interact and fight over a shared resource “contest” competition Plants: chemical interactions (allelopathy)
One plant poisons another with particular chemical compounds either directly (through inhibition) or indirectly (by altering biotic or abiotic soil characteristics) o May serve against both intra/interspecific competition o Expensive Animals : territoriality Marking home territory to prevent competition for resources within a certain area o May serve against both intra/interspecific competition o Expensive Displays of aggression o May serve against both intra/interspecific competition o Expensive Actual fighting rare due to large injury risk Outcomes of competition o Competitive exclusion – local extinction o Reduction in abundance – occupying a realized niche Lower survival – lower density Reduced growth – smaller size Lower reproduction Decreased fitness Decreased population growth o Stable coexistence via intraspecific competition Each species limits itself more than each other o No pattern (other processes more important) Facilitation Mutualism Regulation by pathogens or parasites Stochastic (random) events Niche partitioning o Species minimize competition by becoming a resource specialist Specialists : can only thrive in a narrow range on environmental conditions, or has a limited ability to use resources Have a specialized diet o Can also be generalists and have relatively high niche overlap and compete strongly with other species, or switch resources Generalists : a species that is able to thrive in a wide variety of environmental conditions and can make use of a variety of different resources Have a varied diet Resource partitioning Partitioning in space o Limiting resources are unevenly distributed across the landscape o Different species can use different combinations of resources Therefore – promotes coexistence o Water availability, temperature, and sun exposure all vary with increasing altitude
Plants are sorted along the gradient according to their environmental tolerances and resource requirements Partitioning in time o Phenology : the timing of an organism’s resource use and life history stages o Resources and environment determine the characteristics of communities o Community characteristics Species richness (# of species) Species diversity (abundance and richness of species) Plant growth forms (size and shape) Shrub community vs. forest community vs. shoreline Community structure (complexity of layers and spp. Interactions) Ecosystem function (energy, nutrient, and water cycling)

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