community structure (freshwater) Flashcards
what is a community?
a community is a group of interacting species occurring at a particular place at a particular time
what informs the evenness of a community?
species richness (Number of species) relative abundance (individuals of particular species)
what could more species at the lower trophic levels indicate?
due to more energy available
more niche availability
river continuum concept?
variation in community composition over the space of a river
higher diversity at the top of the river due to more nutrients
variation in community over time?
example spring to august food resources change
limiting resource?
limiting condition?
used by a species to survive
attribute of the environment a species must be able to tolerate to survive
competition past? (look over)
past events that structure the current system
example of how interactions with abiotic and biotic can lead to community composition changes? (study)
regulated (with dam) rivers have high abundance of flies as it is adapted to low water movement
this has a flow on effect as changes in its abundances has effect of changing abundance of different species
the age of what can structure a community?
ecosystem age
intermediate disturbance hypothesis?
the highest biodiversity will be at intermediate disturbance
because good colonizers + good competitors
productivity’s effect on biodiversity?
increased biodiversity up until a threshold of productivity is reached and then biodiversity decreases
habitat size/ complexities effect on biodiversity?
with increasing size increases the number of niches (more heterogenous) and biodiversity increases
what is more important productivity or habitat size/complexity?
complexity/size
because habitat is more of a factor in increasing the length of a trophic chain and therefore increasing biodiversity
island biogeography theories effect on biodiversity?
smaller islands= less biodiversity
more isolated islands= less biodiversity
more species= lower colonisation rates + higher extinction rates
