Slide Set 6 Flashcards
major factors for global patterns in biotic assemblages include?
- temperature
- precipitation
- timing and intensity
plant formations are influenced by ?
climate and soil factors
what is a biome?
A general scheme to classify ecosystems based on plant types and their associated animals
what is a plant formation?
A general scheme used to classify ecosystems based on plant types
whittakers scheme combines both _____ and __________ as governing factors
precipiattion and temperature
the climatic envelope was who’s idea?
woodwards scheme in 2004
vegetation types?
- evergreen needleleaf forests
- evergreen broadleaf forests
- deciduous needle leaf forests
- deciduous broadleaf forests
- mixed forests
- woody savannas
- savanna
- grasslands
- closed shrublands
- open shrublands
woodwards scheme is based on 3 criteria?
forest, grasslands, shrublands
what are the two classfication systems by life form and function?
- Dansereau’s System
2. Raunkiaer’s System
describe Dansereau system
combines life form, function and leaf structure
describe Raunkiaers system?
based on where perennating buds are found on the plant
what are perennating buds?
source of tissue for next growing season
what are perennating buds?
source of tissue for next growing season
the buds are the most ______ vulnerable part of the plant
vulnerable
what are the 7 mjor life forms according to Raunkiar?
- Phanerophytes
- Chamaephytes
- Hemicryptophytes
- Cryptophytes and Geophytes
- Hydrophytes
- Therophytes
what is Raunkiaers system’s goal?
to create a life-form spectrum for a particular vegetation type or zone, then compare the spectra for the different zones
tropical forests are dominated by __________
phanerophytes
Temperate systems dominated by _________
hemicryptophytes
Deserts dominated by ________
therophytes
forest animals are classified by ___________ habit
food
what are the 4 foraging techiques?
- arboreal
- Aerial
- Scansorial
- Ground
what is the niche concept?
The response of a population of organisms (belonging to a particular species) to the full set of conditions, resources, competitors & predators
fundamental niche
the full range of conditions and resources that allows a species population to survive and reproduce in the ABSENCE of competitors and predators
realized niche
the full range of conditions and resources that allows a species population to survive and reproduce in the PRESENCE of competitors and predators
the realized niche is almost always _____ than the fundamental niche, it is never bigger
smaller
the niche of a species can be defined by a number of different __________
dimensions
hypervolume
a niche not limited ot 3 dimensions and involving many more
what are 3 main reasons for population fluctuations?
- recovery after environmental disaster
- fluctuation around carrying capacity
- repeated episodes of colonization
there is a tendancy for ________ ocscillations in predator and prey abundances
coupled
community
An assemblage of individuals of different species that occur together in space and time
climax community concept
Climax community – one that perpetuates itself indefinitely under prevailing climate and soil conditions – a community that remains stable until disrupted by disturbance
succession
The process by which the species composition of a community changes over time
what was gleasons view of the climax community?
- Individualistic approach
- Fixed and definite vegetative structures (monoclimaxes) do not exist
- Specific conditions & random events can alter the course of succession
- Polyclimax model; mosaic of climax types within a region
what was clemensons view of the climax community concept?
- Monoclimax
- Stable and predictable series of species replacements
- Deterministic distribution & abundances of species in the monoclimax
competitive exclusion principle by garrett hardin
complete competitors cannot coexist. This implies that :
- competitors can not occupy exactly the same niche space
- to coexist, there must be some difference in the use of resources; that is, there must be differentiation of their niches
competitive exclusion principle by gause
:if two competing species coexist in a stable environment, they do so because their realized niches are different in some way. This implies that :
– if there is no niche differentiation, then one species must exclude the other
what is niche diffrentiation?
same species :
Occupation of different niches – by employing different feeding strategies, aided by different morphologies
what is the intermediate distrubance hypothesis?
**Diversity is enhanced by moderate levels of disturbance (measured in terms of intensity, timing, frequency)
- Infrequent or low intensity disturbance would allow competitive interactions to play out, resulting in extinctions of poorer competitors, and thus low diversity
- Frequent or high intensity disturbance would mean that only a few species could colonize and complete their life cycles, resulting in a low diversity community
on the scale of disturbance what are the key points?
intensity, frequency, timing, and spatial scale of the disturbance
coexistance and community divercity can be mediated by?
- Spatial & temporal heterogeneity
- Variation amongst individuals within populations in their competitive ability
- Competitive equivalence
- Non-equilibrium conditions
describe an example of spatial and temporal heterogeneity?
- owls & hawks coexist (both feed on small mammals, but at different times)
- creepers & warblers coexist (both feed on insects, but on different parts of trees)
- reduces competition and allows coexistance
what is a keystone species?
- A species that exerts strong effects on the structure of the communities in which it is found, despite low abundance or biomass
- A keystone species is one whose impacts on its community are large, and disproportionate to its relative abundance or total biomass
keystone species was defined by whom?
robert paine 1960s
curent total species count is __________ (eukaryotes only)
1.6 million
we can estimate species numbers by __________ and ________ well- known groups to less well-known groups
extrapolation
correlating
extrapolation
the action of estimating or concluding something by assuming that existing trends will continue or a current method will remain applicable.
hawksworths study of estimating species numbers used ________
ratios
erwins study of estimating species numbers used?
spatial ratios and host specificity
