210 Islands
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Island Ecology An island is any area of suitable habitat surrounded by an expanse unsuitable habitat. NUNATAK (Habitat Island) • Peak surrounded by glaciers • but not itself glaciated • Merrit Lyndon Fernald The basin and range province in Nevada is an example of such a habitat island.
description
islands for ecology 2
Transcript of 210 Islands
Island'Ecology
An#island#is#any#area#of#
suitable#habitat#
surrounded#by#an#expanse#
unsuitable#habitat.
NUNATAK'(Habitat'Island)
• Peak#surrounded#by#glaciers
• #but#not#itself#glaciated
• Merrit#Lyndon#Fernald
The#basin#and#range#province#in#Nevada#is#an#example#
of#such#a#habitat#island.
Three'types'of'Islands
Oceanic
Volcanic
Con@nental
Oceanic'Islands:##Never#connected#to#conAnent;#usually#formed#by#volcanic#acAvity#
and#isolated#from#conAnent#by#deep#ocean.
Con@nental'Shelf
Current'Sea'Level
Former'Sea'Level!
Oceanic'Island!
Sea'Floor
UnderseaVolcano
Examples'of'Oceanic'Islands
•#Iceland
•#Japan
•#AleuAans
•#Bermuda
•#Caribbean#Islands
•#Hawaiian#Islands
•#South#Pacific#Atolls
•#Et#al.
Many#Caribbean#islands#were#formed#by#volcanic#
acAvity#at#subducAon#zone.
Chilean palm (Jubaea chilensis)
Con@nental'Islands:""Formed"on"con+nent;"may"have"formerly"been"connected"to"mainland"by"land'bridge:Indonesia
Current'Sea'Level
Con@nental'Shelf
Con@nent
Submerged'Land'Bridge
Former'Sea'Level
Island
Island'flora'&'fauna
Con@nental
Biota&subset&of&con.nent
Natural&selec.on
specia.on
Island'flora'&'fauna
Oceanic
Founder'effect
Progressive&dispersal
Sophora
ENZED
Two'methods
Dispersal
Vicariance
Various'ways
Con@nental'raOs
Nunataks
Organisms'present'during'the'Cretaceous'(vicariant'groups)'
dinosaurs
Peripatus
Ra@tes
snails
Dispersal'problem
Adapta@on
For'dispersal
Not'usually'survival
Some#plants#have#
developed#seeds#or#fruits#
that#can#be#carried#in#the#
sea#without#being#
harmed.##
Dispersal'problem
Propagules
Founders!of!the!“Island!Biogeography”!
Robert'MacArthur'and'Edward'O.'Wilson'coined'the'term'“Theory'of'Island'Biogeography”'as'this'theory'aXempted'to'predict'the'number'of'species'that'would'exist'on''newly'created'island.
E.O.!Wilson!!and!Robert!MacArthur
Island'life
More'hazards
Less'area
Island'Biogeography:Species'richness'and'island'size
Small'island Less'species
Islands'and'ex@nc@on
More'likely
Small'pops
Founder'effect
Originally&adapted&for&where?
Less'richness depauperate
Island'richness
Not'@meE.O.!Wilson!!and!Robert!MacArthur
Special'equilibrium
ex@nc@on'and'coloniza@on.
Theory
species'richness'decreases'with'distance'from'mainland.
Theory
Larger'islands'should'have'more'
species
Theory
Islands'closer'to'mainland'should'have'more'species
Higher'immigra@on
ImmigraAon#rate#
decreases#as#island#
diversity#increases#
ExAncAon#increases#as#
island#diversity#increases#
Species#equilibrium#on#
islands#is#a#balance#of#
immigraAon#and#local#
exAncAon
Equilibrium#Theory#of#Island#Biogeography
Islands#further#from#
mainland#have#lower#
immigraAon#rates
More#distant#islands#have#
lower#species#diversity
Equilibrium#Theory#of#Island#Biogeography
Smaller islands have lower total populations
Probability of extinction increases with lower population
Smaller islands have lower species diversity
Theory of Island Biogeography
Biogeography'Theory'in'a'NutshellEquilibrium#number#of#
species,#but#constant#
turnover
Migra.on#slows#as#richness#increases
Ex.nc.on#increases#with#richness
Equilibrium#=#rate#of#
exAncAon,#rate#of#
colonizaAon#intersect
Coloniza.on&balances&ex.nc.on
Equilibrium"no."of"species
Island'richness
Habitats'not'area
Edge'effects
Blend'of'habitats
On&islands,&ini.ally,&more&sites&available,&some&similar&to&those&of&the&ancestors&and&some&totally&different&leading&to&
specia.on
More'isolated
Harder'to'get'to
= Less'species
Endemism
High
All'Hawaiian'birds
Higher'in'NZ
Endemism
80%&of&all&vascular&plants
70%&of&all&birds
Na.ve&species
All&na.ve&mammals
All&na.ve&rep.les&and&Amphibs
90%&of&all&fresh&water&fish
Island'Rules
Small'gets'big
Big'gets'small
Viola#spp
Island'Rules
flightless
fearless
plants'dioecious
Flightless
Ra@tes
Parrots
wrens
Shags
grasshoppers
Animal#SpecialAes.
• Flightlessness#conserved#energy#in#cold#
condiAons#and#could#flourish#in#the#absence#of#
terrestrial#mammal#predators.
• GiganAsm#is#another#adapAve#feature#
favouring#heat#retenAon.
• Melanism#also#favours#heat#retenAon#and#
energy#conservaAon.
Island'Rulesgroups'under'represented
ecologically
