evolution of australian biota notes

8/9/2019 Evolution of Australian Biota Notes

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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

evolution of australian biota notes

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