11/22 quiz Flashcards
biogeography
study of the spatial distribution of species
wants to explain why species are found where they are
what can studying islands allow us to do?
learn a lot about the processes that determine species composition and diversity across the globe
who is the “father of biogeography”? what did he discover?
alfred wallace
discovered the fauna of the philippines was more similar to that of africa than of new guinea
what are wallace’s six biogeographic regions?
neartic, neotropical, ethiopian, paleartic, oriental, and australasian
what did wallace’s regions coincide with?
tectonic plates
what did continental drift do?
change locations of continents and oceans
how does a community get its species? (global perspective)
migration - depends on dispersal ability
establishing self upon arrival - depends on a/biotic factors
time - new species from speciation (vicariance, local adaptations, etc.)
how many species should an area have?
can predict based on speciation and extinction events in an area (ignoring migration)
larger geographic area increases…
probability of speciation
speciation often occurs when populations can become isolated (get rid of gene flow)
large areas increase the chance of population…
isolation and divergence
larger geographic area decreases…
the probability of extinction
larger areas can support larger populations -> less chance of extinction by chance events
larger areas increase the geographic range of species, which in turn…
allows species to spread out and decrease extinction risk
smaller populations have a larger probability of…
becoming extinct
smaller geographic areas increase the probability of…
extinction
what is the species-area relationship?
the positive relationship between species richness and area
occurs over a variety of scales
what is the formula for the species-area effect?
S = cA^z
to find number of species
what do the variables mean in the species-area effect?
S = number of species
A = area
z = slope of the line
c = constant
how can we plot species-area effect?
logS = logc +z*logA
logS on y-axis and logA on x-axis
c = intercept of log-log curve
z = slope log-log curve
where have most species-area relationships been studied?
islands, even if not literal islands
lakes, mountain tops (“sky islands”), habitat fragments
what predictions can we make based on the species-area relationship?
more species on large islands
fewer species on small islands
more isolated islands -> more speciation due to less gene and immigration
what are other contributing factors to the number of species on an island?
area of the island
number of species already there (extinction and immigration rates)
habitat heterogeneity
proximity to other islands
who determined the equilibrium theory of island biogeography?
MacArthur and Wilson
what is the equilibrium theory of island biogeography?
island communities reach an equilibrium number of species
what is the equilibrium number of species on an island dependent on?
the immigration and extinction rates of the island
which are both affected by the size of the island and its distance from the mainland