3: Macroecology and conservation principles Flashcards
(32 cards)
What is range size?
Area of geographic distribution
What are the two ways range size is measured?
Extent of occurence
Area of occupancy
What is the extent of occurence?
The area within the range boundary
Scale independent
What is the area of occupancy?
Area of occupied locations within boundary
the summed area of occupied grid cells
scale dependent
What are some characteristics of a small range size?
small population size
increased extinction risk
low climate tolerance
generally lower latitudes
What is Rapoport’s Rule?
When latitudinal extent / range size of organisms at a given latitude is plotted aganist latitude, a simple positive correlation is found (stevens, 1989)
What is a historical explination for rapoport’s rule?
More small ranged species have gone extinct at higher latitudes due to frequent glaciation events
What is the climatic variabilty hypothesis?
Species with the ability to tolerate a wide range of climates have lager ranges
What is Allopatric speciation?
When a new species arises due to geographic barrier splits a population leading to reproductive isolation and then speciation
What is the equation for species area relationships?
S = cA^z
s = species richness
A = Area
What is saturation?
measures the number of species on an island relative to the possible species that could occur given the pool of species on the mainland.
More distant islands are less saturated
Island biogeography theory
Species richness is a balance of immigration and extinction
Immigration rates should increase and extinction rates should decrease with island size and proximity to mainland
What is α (alpha) diversity?
number of species found in a location (richness)
What is β (Beta) diversity?
turnover in species, i.e. change in composition between two locations
or at the same location over time
What is γ (Gamma) diversity?
number of species at a landscape scale
much larger scale than alpha
What three things cause the LDG?
Chance events
Ecological factors (energy / productivity)
Evolution
Chance - SAR
if species are distributed randomly through
space you expect more species in locations with more land area
What is Actual evapotranspiration (AET)?
Measure of energy availability – combines heat and water
What are all the species-energy relationships?
Sampling
more individuals
more trophic levels
dynamic equilibrium
niche position
niche breadth
What is sampling?
(Species-energy relationships)
more energy in a given area allows more individuals to occur, this increases number of species by chance
What is the more individuals hypothesis?
more energy increases species’ population sizes, larger populations have reduced extinction risk thus increasing total number of species present at any one point in time
More trophic levels
(Species-energy relationships)
more energy at the base of a food chain can support more trophic levels
Dynamic equilibrium
(Species-energy relationships)
more energy enables populations to recover faster from disturbance thus reducing risk of extinction
niche position
(Species-energy relationships)
Increased productive energy increases the abundance of the relatively rare resources that are exploited by niche position specialists. In high-energy areas more species of niche-position specialists can
maintain viable populations, thus increasing species richness
