3-Community ecology Flashcards
community
all the species that interact with one another within a defined area
what kind of interactions do community ecologists primarily think about
- biotic interactions
- how do species interact with each other
- what are the fitness consequences of these interactions?
- how do these interactions change with time and location?
Amenalism
occur when an organism inflicts harm to another without any fitness cost/benefit to itself
- / 0
Commensalism
occurs when one species benefits from the interaction, but the other species is unaffected
+ / 0
Mutualism
when two species interact in a way that confers fitness benefits to both
+ / +
Consumption
when one organism eats (or absorbs the nutrients) from another
positive fitness effect for the consumer, and a negative fitness effect on the prey
+ / -
Competition
when individuals use the same limited resources
there are negative fitness consequences for both individuals
- / -
types of consumption
- predation
- parasitism
- herbivory
predation
one organism kills and consumes another organism
1. can also affect the distribution of their prey 2. can positively affect biodiversity of the community (number of species in an area and their relative abundance)
parasitism
one organism lives on/in another and steals its nutrients/resources, usually does not kill host
herbivory
one organism consumes all or part of a plant
COMPETITION
organisms use common resources that are in limited supply
types of competition
- intraspecific competition—between same species
- interspecific competition—between different species
NICHE
the resources used by a species (where it lives, the food it eats) and its relationship with other species (their role in ecosystem)
fundamental niche
based on physiological tolerance, the range of resources an organism is able to use in the absence of biotic interactions
realized niche
range of resources able to be used in the presence of biotic interactions
INTERSPECIES COMPETITION HAS TWO POSSIBLE OUTCOMES
-
competitive exclusion
- one competing species is eliminated from part or all of the site/habitat by a superior competitor
-
stable coexistence
- through niche partitioning!!
- species are able to coexist
- both remain in the site/habitat
outcome depends on the strength of competitors and degree of niche overlap
WHAT HAPPENS IF ONE COMPETITOR IS COMPLETELY SUPERIOR?
if niches only partially overlap:
- both species can co-occur!!
- weaker competitor experiences reduction from its fundamental niche
- competitively excluded from part of niche
- superior competitor experiences no reduction
if niches fully overlap:
- species cannot co-occur
- weaker is competitively excluded from entire niche!
COMPETITION ON EVEN MORE FOOTING CAN LEAD TO NICHE PARTITIONING :O
- competition in the overlap is costly, so species reduce their niche overlap by using area not used by the other species
- realized niche becomes smaller than fundamental niche for both species
- if one competitor were removed, the other species could immediately capitalize on the full range of resources (change was not heritable)
what can competition over time lead to?
EVOLUTIONARY CHANGE
character displacement
heritable change in species’ traits that allow individuals to avoid competition by specializing on different resources
niche partitioning can lead to this!!
traits become more divergent in sympatric populations as compared to allopatric populations
ECOLOGICAL SUCCESSION
a process by which the mix of species in an area changes over time (years to centuries)
Primary Succession
occurs when a new patch of land is created or follows a disturbance that removed all the soil and all living organisms
PIONEEERING SPECIES
Early colonizes that do not require much soil
progression after primary succession
- nothing remains but bare rock/gravel
- organisms need to start from scratch and when they die, their remains will slowly contribute to the fomration of soil
- as the soil deepens, larger plans can colonize the site
- larger plants provide cover and shade, which will restrict the growth of shade-intolerant plants
- eventually a climax community is reached, unless a disturbance occurs to stop succession
Secondary succession
follows a disturbance that has removed some or all living organisms but soil and nutrients remain
what can influence the pattern of succession?
plant traits!
