the niche Flashcards
the niche
= the functional role of a species in a community including activities and relationships
fundamental niche
= the total range of environmental conditions under which a species can survive
examples of niches
- temperature = 1D niche
- temperature and humidity = 2D niche
- temperature, humidity and current flow = 3D niche
ranges of niches
- optimal range (where most individuals are concentrated)
- limit for populations
- limit for individuals
resource utilisation curves
- narrow niches with little resource overlap = relatively little interspecific competition
- broader niches with greater resource overlap = relatively intense interspecific competition
realised niches
= niche where competition occurs (inter/intraspecific)
competitive release
= niche expansion in response to reduces interspecific competition
e.g. habitat ranges of ground doves in the islands of New Guinea
specialised and changeable niches
= niches in a dynamic environment
e.g. newly aggregated mobile sand dunes with isolated fragments of sea lyme grass and couch grass
limits to niches
- altitudinal and latitudinal
e.g. position of trees altitudinally from sub-alpine to alpine
Krummholz
- where stunted trees are found in an alpine transition zone
ecotone
- the transition between two structurally different communities
adaptation
- results from challenges by the environment selecting for genetic characteristics
e.g. Pine in Sierra Nevada, 30m tall at 10,200ft, 2m tall at 10,800ft
phenotype
= the physical expression of a characteristic of an organism, determined by both genetic constitution and environment
e.g. experiment on A. lanulosa at Stanford, showed different phenotypic expression when grown at timber line (3,000m) than when grown at sea level
arctic and alpine plants
- short
- 80% biomass below ground
- often dwarf versions of plants
monocormic
trees with a single dominant axis of growth
polycormic
multi-branched trees
differences in morphology of birch trees
- monocormic in South Sweden
- polycormis in the North due to the harsher environment (high winds and heavy snow)
physical and biochemical differences
- variation in protective pigments (from UV) with latitude/altitude
- organisms at a high altitude/latitude often have cryoprotectants (sugars or amino acids)
resistance to drought
inland populations often more resistant to drought
biomes
= a biological subdivision that reflects the physiological and ecological characteristics of vegetation. Greatly influenced by the relationship between precipitation and temperature
