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Vocabulary flashcards covering key terms and concepts from Chapter 41 lecture on Ecological Communities.
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Biological community
A group of populations of different species living close enough to interact.
Interspecific interactions
Relationships between individuals of different species, such as competition, predation, and mutualism.
Competition
A –/– interaction in which species vie for a limiting resource, reducing survival and reproduction of both.
Competitive exclusion
Principle stating that two species competing for the same limiting resource cannot coexist indefinitely in one place.
Ecological niche
The sum of a species’ use of biotic and abiotic resources—its ecological role.
Resource partitioning
Differentiation of niches that enables similar species to coexist in a community.
Fundamental niche
The full range of environmental conditions a species can potentially occupy and use, without competitors.
Realized niche
The portion of the fundamental niche actually occupied by a species in the presence of competitors.
Character displacement
Tendency for characteristics to diverge more in sympatric than in allopatric populations of two species.
Exploitation
Any +/– interaction where one species benefits by feeding on another, which is harmed (e.g., predation, herbivory).
Predation
A +/– interaction in which one species (predator) kills and eats another (prey).
Cryptic coloration
Camouflage that makes potential prey difficult to see.
Aposematic coloration
Bright warning coloration of animals with effective chemical defenses.
Batesian mimicry
When a harmless or palatable species mimics a harmful or unpalatable one.
Herbivory
+/– interaction in which an organism eats parts of a plant or alga without usually killing it.
Parasitism
+/– interaction in which one organism (parasite) derives nourishment from another (host), harming it.
Endoparasite
Parasite that lives within the body of its host.
Ectoparasite
Parasite that feeds on the external surface of its host.
Parasitoid
Insect (often a wasp) whose larvae develop inside a host, eventually killing it.
Mutualism
+/+ interaction benefiting individuals of both species involved.
Commensalism
+/0 interaction where one species benefits and the other is neither helped nor harmed.
Positive interaction
An ecological relationship (+/+ or +/0) that benefits at least one partner and harms neither.
Species diversity
Measure of community variety including species richness and relative abundance.
Species richness
The number of different species in a community.
Relative abundance
Proportion each species represents of the total individuals in the community.
Shannon diversity index (H)
Metric combining species richness and relative abundance to quantify diversity.
Biomass
The total mass of all organisms in a given area or community.
Trophic structure
Feeding relationships between organisms—the pattern of energy transfer in a community.
Food chain
Linear sequence of trophic relationships from producers to top consumers and decomposers.
Trophic level
Position an organism occupies in a food chain based on its source of energy.
Food web
Network of interconnecting food chains showing complex trophic interactions in a community.
Foundation species
Species that have large effects on community structure because of their high abundance or size (e.g., trees, kelp).
Keystone species
Usually low-abundance species that exert strong control on community structure via pivotal ecological roles.
Ecosystem engineer
Organism that creates, modifies, or maintains habitat, affecting other species (e.g., beavers).
Bottom-up model
Community organization where nutrient supply and primary producers control higher trophic levels.
Top-down model
Community organization where predators control herbivores, which in turn influence plants (trophic cascade).
Trophic cascade
Indirect effects of predators across multiple trophic levels, often alternating +/– impacts.
Biomanipulation
Deliberate alteration of an ecosystem by adding or removing species to restore balance (e.g., removing fish to reduce algae).
Disturbance
Event that changes a community by removing organisms or altering resource availability (e.g., fire, storm).
Intermediate disturbance hypothesis
Idea that moderate levels of disturbance foster greater species diversity than high or low levels.
Ecological succession
Sequential change in species composition of a community following disturbance.
Primary succession
Succession that begins in a virtually lifeless area where soil has not yet formed.
Secondary succession
Succession occurring where a disturbance has cleared existing community but left soil intact.
Facilitation (succession)
Process where early species modify the environment, making it more suitable for later species.
Species-area curve
Relationship showing that larger geographic areas tend to have more species.
Island equilibrium model
Theory predicting island species richness based on immigration and extinction rates, influenced by island size and distance.
Evapotranspiration
Total water loss from soil plus transpiration from plants; correlates with energy availability and diversity.
Zoonotic pathogen
Disease-causing agent transmitted to humans from other animals.
Vector (disease)
Intermediate species (often an arthropod) that transmits pathogens between hosts.
Sudden oak death (SOD)
Tree disease caused by the protist Phytophthora ramorum, altering forest community structure.