module 12 Flashcards
Biodiversity
measure of the different kinds of organisms in a region or other defined area
species richness
the number of species in a region or specified area
species diversity
is the number of species in the community and their relative abundances
species evenness
the degree of equitability in the distribution of individuals among a group of species. maximum evenness is the same number of individuals among all species
simpsons index of biodiversity
sometimes written as 1-d such that the most diverse regions are the close to 1
phylogenetic diversity
an index that quantifies biodiversity while incorporating the phylogenetic differences in a sample
species endemism
species that are unique to a geographic location; organisms that are indigenous to a given region are not endemic to it if they are also found elsewhere
more energy =
more primary productivity = more niches
species energy hypothesis
there is more energy (sunlight) in the tropics so more primary productivity; more niches, and more species
climatic harshness hypothesis
tropical climate presents fewer stresses than temperate climate, so more species
climatic stability hypothesis
tropical climate is more stable over time
time and area hypothesis
most lineages originated in tropical environments throughout the cenozoic because the earth in the past was warmer, few lineages have been able to adapt to temperate regions
diversification rate hypothesis
the rate of increase in diversity is greater in the tropics because of a higher speciation rate, lower extinction rate, or both.
gilinksy and bamback
found that rate of origination within orders decreased over time, while the rate of extinction within orders increased over time
stanley
suggests that speciation extinction rates are correlated because both are influenced by intrinsic features of the organism
lineage through time plot
measure the rate of cladogenesis as a function of time, clades that diversify at a constant rate will have an approximately straight line in a lineage through time plot
EO wilson definition of extinction
termination of any lineage of orgnaims from subspecies to species and higher taxonomic categories from genera to phyla, can be local, or total (global) in which all populations vanish
what populations are more vulnerable to extinction?
small populations
what is the minimum viable population size?
the point at which a smaller population becomes prone to extinction, typically 10s - 100s of individuals, related to species-area effects
what percentage of species are extinct?
> 99.9%
background extinction
the total sum of extinction lineages over time
Van halen
provides evidence that the likelihood of species extinctin is independent of the age of the taxon
Jablonski
the likelihood of species extinction is inversely proportional to the size of the species range
Mass extinction
the sudden disappearance of a large number of species (60%) in a short period of time
