Population Ecology Flashcards
What is a biological community
An assemblage of populations of various species living close enough for a potential interaction (competition, predation, herbivory, symbiosis, and disease)
Fitness effect
Influence of competition of reproduction (fitness of offspring)
Competitive exclusion
Local elimination of a competing species
Competitive exclusion principle
two species competing for exactly the same limiting resources cannot coexist in the same place
Ecological Niche
The total of a species use of biotic and abiotic resources
Fundamental niche
entire set of conditions under which an animal can survive and reproduce
Realised Niche
Set of conditions actually used by animal after interaction with other species (competition) has been accounted for
Barnacle example of fundamental niche and realised niche
once a competitive species was removed from the rock base, another barnacle was able to expand into entire rock - can tolerate entire rock.
Resource partitonisn
The differentiation of ecological niches, enables similar species to coexist in a community. (i.e. adaptations for tree-dwelling, floor dwelling, etc)
Character displacement
Two competing species in the same environment develop divergent traits to reduce competition between the species
Example of character displacement (Galapagos finches)
Beak size related to range of seeds that can be eaten, allowing each species to exploit differing resources (thereby reducing competition as they aren’t competing for the same resource) - When living on islands separately - they have similar beak sizes (lots of overlap). When living together on islands - their beak size is remarkably different = Character displacement (result of competition over many generations which lead to specialisation)
Batesian Mimicry
Harmless/palatable species mimics and unpalatable or harmful model
Mullerian Mimicry
Two or more unpalatable/harmful species resemble each other
Herbivory
Interaction where herbivore eats SOME parts of plants or alga
Parasitism
One organism (parasite) derives nourishment/structure from another organism (host), which is harmed in the process
Dominant species
Ecological dominance is the degree to which one or several species have a major influence controlling other species in their ecological community (more often species with large biomass)
Example of dominant species
mangroves, high abundance, high influence
Keystone
Not the most abundant species in their community but have a disproportionate influence on community structure
Sea star example of keystone species
In the absence of sea stars, the mussels (its prey) dominated the community as their expansion was not limited by predator.
Otter example of keystone species
Otters eat sea urchins, allow kelp forest to flourish. Due to overfishing, orca turned to eating otters, urchins became abundant, kelp forests died. Otters are therefore keystone species for kelp forest diversity.
What are keystone species often (predator, prey etc??)
Predator, keep population in check
Ecosystem “Engineers”
Some organisms exert influence by causing physical changes in the environment that affect community structure
Example of ecosystem engineers
Beaver dams can transform landscapes on a very large scale
Non-equilibrium model
Decades ago, most ecologists favoured the view that communities are in a state of equilibrium. * Recent evidence of change has led to a non-equilibrium model, which describes communities as constantly changing after being buffeted by disturbances.
