ecological niche Flashcards
niche
organisms place in biotic environment (relation to food and enemies) and abiotic environment (physical surroundings)
Hutchinson’s niche
n-dimensional hyper volume (n=number of environmental factors)
single niche axis
zone of intolerance, zone of stress, optimal zone
fundamental niche
the range a species could occupy without competitive pressures
realized niche
the range a species actually occupies
how does environmental complexity relate to niches
the more complex an environment, the less oportunity for competition
-more species diversity
Karr and Roth experiment
- measured height of trees (to assess complexity)
- measured number of warbler types in trees
- more complexity = more biodiversity
why can phytoplankton/algae/diatoms coexist
- partially due to complexity of environment
- mostly due to varying trophic positions and different nutritional need ratios
what happens if 2 species have same needs exactly
- cannot coexist
- one will outcompete the other
Park’s flour beetles
- both types have large niches when no competition
- smaller niches when coexisting
- T. castaneum wins in hot, wet environments
- T. confusum wins in cold, dry environments
- first colonizer wins in intermediate environments
Priority effect
when the first colonizer wins at competition
Gause’s competitive exclusion
- When grown allopatrically, they followed logistical curve
- when raised sympatrically, p. aurelia competitively excluded p. caudatum
- p. aurelia’s k was lowered though
Barnacles in intertidal zones
-Semibalanus balanoides is restricted to lower- mid tidal positions because it is sensitive to drying out
Chthamalus stellatus is restricted to upper tidal positions because of competition with the other guy
Heske’s granivorous rodent experiment
- if you remove big grainivorous rodents, there will be an increase in the number of small ones
- insectivore rodents shouldn’t be impacted
niche partitioning
basically figuring out how two species can coexist by sharing resources and limiting their fundamental ranges
-usually involves different use of resources
DW analysis
- figuring out the mean usage of a resource and finding the upper and lower limit by adding and subtracting the standard deviation
- no coexistance if ranges overlap
warbler example of niche partitioning
Robert McArthur found that different warblers used different sections of the same tree
temporal partitioning example
common spiny mouse and golden spiny mouse are both nocturnal, but when grown sympatrically, the golden one becomes diurnal
Diamond fruit doves
big ones eat big fruit; small ones eat small fruit
Niche partitioning between sexes
this happens
Character displacement requirements
- the differences in sympatry must be greater than in allopatry
- the differences cannot be due to founder effect
- difference must be genetic
- must have effect on resource use
- must be competition for resource
- not due to different available resources
Hutchinson’s ratio
- when organisms live in sympatry, tend to have size ratios of 1:1.1 to 1:1.4
- e.g. felis canine sizes bt sexes
Historical replacement
- when one species replaces another
- slides mention azure and blue tits, but this is honestly just dispersal with some overlap
- starlings and house sparrows evict native bluebirds and flickers from cavity nest sites
contiguous allopatry
- 2 species are allopatric, but the regions in which they live are adjacent to each other
- e.g. chipmunks along sierra nevada mountains
- e.g. warblers on mt. karimuni
chipmunks in contiguous allopatry
alpine, lodgepole pine, yellow pine, least
-lodgepole is most dominant, but yellow pine is dominant to the least
