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Evolution of Australian Biota
Evidence for the rearrangement of crustal plates andcontinental drift indicates that Australia was once part of anancient super continent
Theory of Gondwana
Theory of continental drift > proposed by German scientistAlfred Wegener in 1915
Identical fossils of plants and animals had been
discovered on opposite sides of the Atlantic ocean Sggested that all continents were connected > forming
a large land mass! which he called Pangaea The continents then split into smaller nits of land and
drifted to their crrent location
Se"ence of events
225 mya:#angaea splits into two land masses >
$arasia and Gondwana 180 mya: both Gondwana and $arasia begin to brea%
p 135 100 mya: Gondwana brea%s into three parts&
Africa and most of Soth America& Antarctica! Astralia!'ew (ealand and 'ew Ginea& India > began driftingnorthwards to become part of Asia
80 mya: 'ew (ealand brea%s away
65 mya:Astralia begins to separate from Antarctica
60 mya:)nal separation of tip of Soth America from
Gondwana 45 mya:Astralia becomes a separate continent >
begins to drift northwards and becomes drier and hotter
*vidence spporting Gondwana
#late tectonic theory Theory proposed in the 19+,s > continents cold move
-ontinents were carried on large plates beneath the
ocean > plates were positioned on top of the semi.molten interior of the earth
As the plates move they cold&
~ -ollide > converging
~ Slide past /one slides beneath the other0 >subduction
~ ove apart from each other > diverging
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Geological The contries )t very
well together >
especially the continental shelfs as opposed to theshorelines Similarity in the roc% strata /layering of roc%s0
id.ocean ridges > radiometric dating has proved that
roc%s closer to the mid ocean ridges are yonger thanthose frther from the margins
2ossil Glossopteris fossils have been fond on all the
continents that once formed gondwana > 35, millionyear old roc%s all had these fossils
$abyrinthodonts were amphibians which resembled
salamanders Are %nown to have lived in Astralia! Antarctica 4 Soth
Africa > all part of Gondwana
2lightless birds The atite are a grop of 6ightless birds and each
continent is represented by at least one species of6ightless birds7
The 8iwi! *m! hea and strich > continents mst
have been connected as the birds can:t 6y
arspials and mammals arspials began to evolve on $arasia and spread
soth to Gondwana as the split was occrring >marspials spread as far as to the Antarctica andAstralian continent as there was still a land connectionbetween the Soth America and the Astralian;Antarctica continent
#lacental mammals arose on $arasia > coldn:t reach
the sothern hemisphere as the land connectionbetween soth America and Astralia no longer e
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'othofags is fond in Astralia! Antarctica! Soth
America! 'ew Ginea and 'ew -aledonia > continentswere once =oined
#roteaceae > 6owering plants fond in Astralia and
Soth Africa
*g7 The Waratah and an%sia
-rrent research
?'A se"encing of the amino acids of the platyps!marspials and mammals > monotremes mil% is very di@erentto the mil% of placentals and marspials
?'A se"encing > able to calclate that the monotremeslineage diverged from the marspial and placental lineageabot 1+ B 1C+ million years ago! which coincides with theappro#alaeontologists have fond fossiliDed grinding teeth! whichhave characteristics of both placentals and marspials!indicating that they have a common ancestor
Similarities between crrent and e
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*nvironmentE swamp areasin Feensland
ody strctreE reptilianscales! long and strong tail!large snot and sharp
teeth?i@erences
Tingamarra swampcrocodile was mchsmaller than the presentday fresh water andsaltwater crocodiles
The changes in Australian ora and fauna over millions ofyears have happened through evolution
Variation: the di@erences in the characteristics of individalsbetween a poplation! both genetically and appearance
Sorces of variation
tation andom segregation of chromosomes dring mitosis
-rossing over dring meiosis
Se
important in evoltion
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Environment:has an e@ect on the variation of characteristicshowever is not passed on to o@spring
*g7 2at layer! dying yor hair
Some variation is a combination of environment e
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change 2ire frther changed the vegetation
These changes in vegetation impacted the food sorce ofmany animals > gradally the fana of Astralia changedbecase of this
-hanging habitats
220 110 mya: dinosar age > Astralia was connected with
Antarctica and had a cool! wet climate and cold e present day land was covered in shallowwater
45 mya:Astralia became a separate continent > great la%es
remained in the interior of Astralia Evidence: fossils of a"atic organisms have been fond
in areas that are inland and dry in present day Astralia> sggesting the presence of la%es
20 mya:Astralia was isolated from the other sothern
continents as it drifted northwards > climate grew warmer btremained wet
Evidence: fossiliDed remains of trees give information in
their ring patterns that spport the changes in climaticconditions
8 mya:Astralia contined to drift northwards and becamemch drier
100 thousand years ago:time of megafana > Astralia wasvery close to its crrent day position and was temporarilyconnected to Tasmania and 'ew Ginea
! unti" 10 thousand years ago:Astralia went throgh cyclesof high and low sea levels
5 thousand years ago:Astralia:s climate contined to dry >interior land became dry and arid
Evidence: no fossil remains have been fond of
Astralia:s present day vegetation which is sited to
harsh climates > indicating it is a recent vegetation andnot part of the vegetation millions of years ago
ariations in water and temperatre availability
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-hanging 6ora and fana
The distribtion and abndance of present day plants inAstralia have main originsE
Those already on the continent when it split from
gondwana Those that dispersed from Soth *ast Asia to Astralia
Introdced species
The origin of animals that led to the present day fana areE riginal residents: > those that were on the continent
when it split from Gondwana Asian immigrants: that arrived when sea levels were
low Those introdced by immigrant traders or late arrival
aborigines Those introdced by *ropean immigrants
65 mya: wet and warm climate that spported the large
variety of 6ora and fana and rainforests > the dominantvegetation type before the split
45 mya:The climate dried as Astralia separated and beganto drift north > bsh land replaced rainforests in the inlandareas
Evidence: fossils at iversleigh in Feensland show that
inland forests dried p and vegetation changed fromforest to woodlands
Gm trees! wattles and many wild 6owers became common inAstralia:s forests as the climate dried
'ew fana inclded salt water crocodiles and bdgerigars
The climate went throgh a period of 6ctation from wet to
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dry and the pattern of forests! grasslands and desertscontined to change
egafana 6orished
Indigenos people arrived and sed )re to clear vegetation Evidence:fossils show an increase in the commonness
of carbon deposits which coincided with the arrival ofhmans
#bout 500 years ago:climate became considerably drier >
lightening gave rise to )res Evidence:carbon deposits dating bac% to that time and
the presence of the pollen of )re resistance speciesreveal a )re.vegetation: relationship
ainforest was replaced by more )re.tolerant open forests >inclding ecalypts which had frits: that brst open as areslt of the heat of )re
Evidence: plants have evolved in isolation! showingadaptations to the dry! harsh climatic conditions
Grasslands developed in the center of Astralia > sea levelshave risen and fallen and erosion has occrred so ntrientshave seeped from the soil reslting in ntrient poor soils
Astralia:s ni"e 6ora
#lants are able to withstand )re and grow in soils lac%ingntrients are characteristic of Astralia
* grow in ntrient.poor soils Sclerophyll B hard leaf > evolved in many ways to allow
them to se low levels of ntrients
Some plants developed mtalistic relationships involvingtheir roots and soil bacteria and fngi
Jeathland species are )re.resistant and their seedlings onlyemerge following a )re
The arrival of the *ropeans and sheep in6enced Astralia:s
6ora assive loss of perennial plants occrred as a reslt of
overgraDing *rosion followed > dst storms %illed o@ several native
mammals *ropeans started clearing the land for agricltre >
rainforests diminished frther
odern rainforests are very diverse > contain many plantsthat are direct decedents of the original Gondwanan species
odern 6ora is di@erent to other continents > many speciesfond e
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common
Astralia:s ni"e fana
ost living marspials today are fond in Astralia > some
e
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. eplaced by ecalyptforests
-limate became hotter 4drier. 2ires bro%e ot >
initially de tolightening
2lora and fana that cold
srvive droght 4 )re6orished
the animals > increasethe abndance of theanimals available tohnt
Jmans hnted megafana
as they were slower Aboriginal people %illed
animals that were largerthan they were
#ossible that the dingocold have driven thethylacine and theTasmanian devil toe
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become di@erent B -onvergent evoltion
Sggested that organisms that started o@ distantly related!bt ebelonged to di@erent species
bservation forced him to discard the idea of )
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and animals were created toserve manL
rganisms cannot becomeintelligent beings
Continuation of species has resulted, in part, from the
reproductive adaptations that have evolved in Australianplants and animals
The role of meiosis
The importance of meiosis is to ensre that the characteristic
chromosome nmber is maintained dring se
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-ells that are involved with se the chromosome nmber ishalved
eiosis
-ell division that occrs in the se one maternaland one paternal
Process:
17 -hromosomes line p in pairs
37 -rossing over occrs > arms of homologos
chromosomes e one entire
chromosomes of each cell moves into a daghter cell Two daghter cells that have been formed repeat the
previos steps -hromatids separate from each other moving to
opposite poles > reslts in for daghter cells! eachwith half the genetic material
2ertiliDation then occrs when gametes of a male and
female fse together
Internal and etherefore the nmber of
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temperatre is controlled Small nmber of Dygotes
prodced > very few perish reeding occrs seasonally
Dygotes is large reed fre"ently de to lower
fertilisation sccess rate
In an a*uatic environment In an a*uatic environment
Sccessfl method of
fertilisation in thisenvironment
2ewer gametes are re"ired >
higher chance of the gametesniting
Msally highly sccessfl >
gametes don:t dry ot ordehydrate
rganisms mst prodce
large amonts of gametes tocompensate to the low
sccess rateIn a terrestrial environment In a terrestrial environment
nly fertilisation possible on
land ?irect transfer of gametes
avoids dehydration and loss 2ewer female gametes are
re"ired Jigh sccess rate >
environment is enclosed in a
con)ned space
'ot sccessfl > reliance on
water environments
Advantages Advantages
Gametes not e
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eprodctive adaptions in animals
Animal +ertilisation ,ametesproduced
Survival rate
(eptiles Internal
fertilisation *ggs are
thendepositedotside themothersbody
2emale prodce
1, ales prodce
1,, thosands
Increased becase of
internal fertilisation *ggs protected by
parents in variosways > hidden!protected with body
N,O of the o@spring
srvive+ish ony )sh >
einternal
Smaller amont
of femalegametes
$arger amontof malegametes
$arge nmber of
both male andfemale
Srvival rate is low >
lots of gametes areprodced
5O of the o@springsrvive
Amphi'ians
*
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arineanimalsEStaghorn -oral
Sheds millions of gametes into the sea >
environment helps fertiliDation occrring schas tides and water temperatre
When one coral starts to spawn! pheromones
are released to stimlate nearby individals to
also spawn. -oordinating spawning over a wide area
AmphibiansESothernGastricrooding 2rog
* absorb
ntrients from the mother. $ast for +.N wee%s > female doesn:t eat. 2rogs are regrgitated
irdsE rshTr%ey
2ertiliDation is internal bt develop in eggse
place their eggs. Jeat from decomposing of leaf litter %eeps
the eggs warm. Adding or removing material controls the
temperatreeptilesE-rocodile
2ertiliDation occrs internally > female lays
eggs in the sandban% #rodce large yol%y eggs containing sPcient
food reserves from more elaboratedevelopment
onotremesE#latyps
*ggs are fertiliDed internally then deposited
otside the body to contine theirdevelopment
*ggs are incbated in a nest or specialiDed
poch Qong hatchlings obtain mil% from mammary
glands by lic%ing her s%inonotremesE
*chidna
#laces eggs into an abdominal poch where
they stay for N wee%s Qong sc% mil% from the s%in of their mothers
stomacharspialsEed 8angaroo
Internal fertiliDation
o@spring at di@erent stages > older ot of
the poch! newborn developing in the poch!embryo in ters
#rodces two types of mil% simltaneosly
eprodctive adaptations of plants#ollination
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#rocess re"ired for plants to se thestigma
#ollen then travels down the style within a pollen tbe to the
ovles contained in the ovary
When pollen from the 6ower:s anther pollinates the same6ower:s stigma is it called self pollination
When pollen from a 6ower:s anther pollinates a 6ower:sstigma from a di@erent plant its called cross.pollination
In most plants pollen is prodced at a di@erent time from
when the stigma can receive it to prevent self pollination
.ind pollinated Bird pollinated Insect pollinatedPetals Small and green $arge and colorfl >
red and orangeMsally large andcolorfl
Scent Msally absent arely fragrant asbirds can:t smell
ften present asinsects are highlyattracted to scent
Nectar 'one $arge amonts ofnectar
#rodced at the base ofthe 6ower so the insect
mst enter the 6owerto get it
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Anthers
#rotrdes! so pollenis easily blown o@by the wind
-ommonly lowerthan the stigma!often colorfl
*nclosed within the6ower
Stigma #rotrdes! longfeathery and stic%y
to increase srfacearea for trappingthe pollen
Jigher than theanthers! often
colorfl
*nclosed within the6ower! stic%y and
commonly above theanthers
Pollen Small light grains!large amontsprodces
Stic%y or powdery!small amontprodced
elatively large grainsand often stic%y! smallamont prodced
#ollination by animals
Animals that act as pollinators se the nectar or pollen in
6owers as a sorce of food Scent! color! mar%ings! shape and nectaries all attract
di@erent animals
#ollination by deceit
Some orchids which 6owers mimic the shape of female insects> male insects will attempt to mate with them and pollinatethem
Seed dispersal
An advantage for a plant to spread seeds over a wide distance> prevents over crowding
?ispersed by wind or animals
-ethod ofdispersal
%escription Examples
.ind Seeds may have
di@erent adaptationsto assist thedispersal over longdistances by wind
2ine light
aerodynamicseeds egcasarina
Winged seeds eg
ha%ea 2eathery papps
eg native daisiesAnimal Seeds may possess
hoo%s or barbs tocatch on animals fr
2rits may be eaten
and seeds are thencarried in the gtand deposited in
faeces
-olorfl frit eglilypilly
Stic%y frit eg
mistletoe
rrs or hoo%s egbirdlime tree
Throgh animal
gt eg7 'itre bsh
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+ire Some seeds arestored ntil )recases pods to open
*calypts andan%sias
.ater Seeds may 6oat onwater and bedispersed distancesover di@erent waterbodies
Water gms andmangroves
Explosion Some seeds may bee=ected from pods athigh speeds7 Thepods e
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nfavorableconditions
*g7 Spinife< srvives in saltyconditions throgh the seof vegetative propagation
. Short food spply
. Small matingpoplation
-an "ic%ly reprodce. Time restraints. apid recovery is
needed*g7 The colony wattle cansend p shots from theoter roots which grow into
separate plants of theparent dies
-an prodce a largenmber of o@spring
@spring have the samegenetic material as theparent and wold be wellsited to a stableenvironment
*g7 The grooved brain coralreprodced by bdding
when conditions arefavorable
environments
Sexualreproduction
@spring are geneticallydi@erent and possiblybetter adapted to a newand changingenvironment
A more energetic process