Slide Set 11 Flashcards
what are the 4 island types?
- continental
- island acres
- hotspot islands
- terrains and accretion
where did continental islands originate?
- part of continental landmass
- formed by rising ocean levels and separated by tectonic processes
describe the origin of island acres
- volcanic activity
- old ocean rust subducted causing stresses nearby on the overlying plate; volcanic eruptions build new islands that rise above the seafloor
describe origin of hotspot islands and seamounts
- fixed hotspots scattered throughout the earths mantle
- volcanoes rise from the seafloor, plates move and islands born
- erosion reduces islands seamounts
describe formation of island chain
- erosion flattens the top of islands and seamounts
- seamounts are islands of biodivercity
seamounts
islands of incredible biodiversity, poorly known and being destroyed rapidly
what is the bend in the emperor seamount
Hawaiian island chain suggested to be caused by a change in direction of the movement of the pacific plate about 43mya
what are the 3 pacific islands
- continental (new zealand, new caledonia)
- island arc ( the aleutians, the kuriles)
- hotspot islands (tuamato ridge, hawaiia islands, archipelago)
describe terrain
a small area where geology is different from surrounding regions
describe accreted terrane
landmass that originated as an island arc or micro continent that was later added onto a continent or other landmass
describe archipelagos
variation in size and degree of isolation among islands
what is the equilibrium theory of island biogeography
role of rates of immigration and extinction in controlling species divercity
islands usually have ________ species than comparable mainland areas
fewer
often the relative ____________ of species on islands is not the same as in comparable areas on the mainland
density
often island densities are _________ than those con specifics on the mainlands
higher
what are the patterns in island species composition
harmonic and disharmonic
Harmonic biotas
balanced species composition similar to mainland
- expected if species are assembled randomly from mainland source pools
dis harmonic biotas
unbalanced species composition is different from mainland composition
- expected if non random processes are important
active dispersal
flight, ability to cope with seawater
- bats and birds and insects
passive dispersal
high altitude winds, high velocity winds, ocean currents, hitch hiking
- via spores, fungi, seeds, fruits, egg masses, insects and some vertebrates
many island species are _________ rather than specialists
generalists
why are island species generalists
- role of resource limitations compared to mainland areas, food resources have lower standing stocks and renewal rates
- organisms that have lower demands are less fussy and have a greater probability of establishing a persisting population
island food resources are _________
limited
what are advantages of being a small bodied generalist
- small animals need less
- different sources
- small animals can maintain higher max pop densities
- such populations are less susceptible to extinction through demographic processes
in general the greater the area the _____ the number of species supported
greater
is island species relationship linear?
no, richeness increases less rapidly for larger islands
S=cA^(z)
smaller islands have greater rates of __________
extinction
density overcompensation on small islands is common because?
large vertebrates and predators are absent,
absence of cogners (other members of feeding guild), reduced competition, high densities of insects and food resources, surrounding water prevent emigration and immigration
what is the island rule for body size?
tendency for small animals to become bigger and for big animals to become smaller, seems to apply for most mammals and some birds,snakes and turtles and some marine creatures
dwarfism
big animals become smaller
gigantism
normally small animals become bigger, trend seen in herbivores and seed eaters
for small animals what are the 3 factors that promote gigantism?
- immigration selection
- intensified transpacific competition
- ecological release from large competitors and predators
for large animals what are the 3 factors that promote dwarfism?
- ecological release from predators
- intensified intraspecific competition
- resource limitation and specialization for insular niches
what is diamonds study of non marine resident birds?
only islands close to source have close to the expected number of bird species
- greater the distance from source pool the more depaurate the avifauna
as distance increases non volant mammal species richness _________ fro islands in the st lawrence
decreases
islands in the central and eastern pacific have ______ gnerea
fewer
islands are ________ of species from a source pool of species living on mainland area
recipients
the number of species received by an island depends on what 3 things?
- island size
- Island distance
- the source pool of species and their characteristics (richness and vagility)
islands that are far away have _____ rates of immigration than islands that are closer to source pools of species
lower
larger islands would have _____ rates of extinction, while smaller islands would have ________rates of extinction
lower, higher
if there is plants present is it ____likely for there to be animals present
more
MacArthur and Wilson stated
distance or isolation affects the rate of immigration, and size affects the rate of extinction
*these control at equilibrium the number of species and the rate at which species turn over
two equal sized islands that differ in distance from the source pool have the same __________rates but different _________ rates
extinction, immigration
two different sized islands would have the same rate of __________ but different rates of ___________ where they would be greater on the smaller island
immigration, extinction
immigration and extinction are ________ processes
independent
