Ch 41: Ecological Communities Flashcards
Define niche, fundamental niche, realized niche
- Ecological niche: The combination of a species’ physical habitat and its ecological role in that habitat
- Fundamental niche: The full range of climate conditions and food resources that permit the individuals in a species to live.
- Realized niche: The actual range of habitats occupied by a species
Recognize what determines the size of a niche
- Competition with other species can determine the size of the realized niche.
- Two species cannot occupy the same niche indefinitely
Define competition
Definition: When there are fewer resources than required by the number of individuals that live in the immediate area. Competition negatively impacts both competitors; each spends energy it would not spend in the absence of the other.
Define competitive exclusion
Competitive exclusion - When populations of two similar species compete for the same limited resources, one population will use the resources more efficiently and have a reproductive advantage that will eventually lead to the elimination of the other population
Define resource partitioning
Resource Partitioning refers to the division of resources to avoid interspecific competition for limited resources in an ecosystem.
- allows division of feeding niches.
- decreases competition between the species
- allows occupancy of different niches
- therefore optimize survival for all species
Define keystone species
A species that is not necessarily abundant in a community yet exerts strong control on community structure by the nature of its ecological role or niche.
- reduces the competition
- allows more species to co-exist
Define predation
When one organism, predator, feeds on another, prey
- Types of predators
- Carnivores
- Herbivores
- Predator and prey populations tend to cycle instead of maintaining a steady state
Define coevolution
- Coevolution: when each of two species adapts in response to the selective pressures imposed by the other.
- Adaptation of predator
- Physical: claws, teeth, stingers, poison…
- Sensory: eyesight, smell, hearing…
- Defensive adaptations of prey
- behavioral: hiding, fleeing, herds/shoals, warning calls..
- morphological: camouflage, spines (cactus), warning coloration, mimicry..
- Batesian mimics: A harmless species mimics a harmful species
- Mullerian mimics: Two species mimic each other’s defenses
- chemical: alkaloids (plants & animals), sprays (skunk)…
- Adaptation of predator
Define symbiosis
- refers to close interactions between members of different species.
- three types: mutualism, commensalism, parasitism
Define mutualism
- Mutualism: Mutualism is a +/+ interaction that benefits members of both of the interacting species.
- Species 1: Benefitted
- Species 2: Benefitted
Define commensalism
- Commensalism: An interaction that benefits the individuals of one species but neither harms nor helps the individuals of the other species (+/0)
- Species 1: Benefitted
- Species 2: No effect
Define parasitism
- Parasitism: Parasitism is a +/- exploitative interaction in which one organism, the parasite, derives its nourishment from another organism, its host, which is harmed in the process.
- Species 1: Benefitted
- Species 2: Harmed
Define disturbance, succession, climax community
- Disturbance: A disturbance is an event—such as a storm, fire, flood, drought, or human activity—that changes a community by removing organisms from it or altering resource availability.
- Succession = Series of changes that occurs in a community following disturbance (ex: fire; earthquake, human interference) or appearance of new habitat (on a dead volcano)
- Primary Succession: A type of ecological succession that occurs in an area where there were originally no organisms present and where soil has not formed yet
- Secondary Succession: A type of ecological succession that occurs where an existing community has been cleared by some disturbance that leaves the soil or substrate intact.
- Climax community is the final stage of succession
Give examples of different types of interspecific interactions and how each participant is impacted by the interaction
- Competition → - / -
- Predation (Carnivores and Herbivores) → + / -
- Parasitism → + / -
- Commensalism → + / 0
- Mutualism → + / +
Recognize that patterns of interactions and associations between different species can change
- Associations are not fixed and can change over time
- Egrets catch insects that buffalo stir up, but the buffalo are not affected = commensalism
- Egrets spot a lion and poor sighted buffalo take warning = mutualism
