L09- spesies baru

7/30/2019 L09- spesies baru

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BAGAIMANA SPECIES BARUMUNCUL

apakah asal usul biodiversitiyang kita lihat hari ini?


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biodiversity results from the

process of evolution and speciation

HOW we define species also has amassive impact on our view of'biodiversity - the study ofTAXONOMY


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spesies-spesies sentiasa berevolusisepanjang masa, oleh itu kita boleh menyiasatproses kemunculan spesies baru denganmelihat pada spesies yang ada pada masasekarang.

Dilwynnia sp.


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dengan demikian kita boleh lihat pada kelainanpola variasi pada spesies yang diperhatikan buatmasa kini, dan cuba memahami bagaimana variasiini terjadi dahulu.

Darwin explains evolution..

Those animals

that survive

and reproduce .

are those animals

that survive

and reproduce.


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Proses Asas.

Tumbuhan dan haiwan menghasilkan banyak

zuriat, lebih daripada yang diperlukan bagimengekalkan populasi

wujud persaingan dalam kalangan zuriat untukbermandiri kerana sumber yang terhad

ciri-ciri zuriat adalah pelbagai

sesetengah individu dapat beradaptasi denganpersekitarannya dengan baik berbanding yang lain


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individu-individu ini akan mempunyai

beberapa kelebihan untuk bermandiri

individu-individu yang dapat beradaptasidengan paling baik akan membiak dan akan

menurunkan ciri-ciri mereka kepada zuriatmereka.

dan seterusnya.


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proses ini mempunyai beberapaandaian

proses pembentukan spesies seringkaliberlaku apabila populasi terpencil (secarageografi?)

proses pembentukan spesies seringkaliberlaku apabila terdapat tekanan terhadappemilihan adalah tinggi (misalnya hanya

beberapa individu dapat terus hidup iaitu yangmempunyai variasi mempunyai kelebihanyang kompetetif)


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ini akan berlaku apabila sumber (air?nutrien?) adalah terhad

individu-individu yang berjaya untuk terushidup akan menjadi pengasas kepada generasiakan datang

seterusnya kumpulan baru akan terpisahsecara genetik terutamanya apabila terdapat

pemencilan secara geografik) dan tidak dapatmembiak dan mereka akan membentuk spesiesbaru


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Pola-pola pada peringkat spesies

dalam komuniti hutan hujan kita mempunyaikepelbagaian(diversiti) pada peringkat FAMILItetapi setiap famili mempunyai kurang spesies

oleh itu di hutan hujan terdapat banyak jenisspesies dan kebanyakannya tidak ada kaitanantara satu sama lain dan berasal dari familiyang berlainan


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Hutan hujan


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idi kawasan vegetasi yang kaya terdapat

diversiti SPESIES, utetapi bilangan familiyang sedikit secara relatif

eg in W.A.89 famili

5 famili = 56% of spesies

eg

Proteaceae (Grevillea, Banksia)Myrtaceae (Eucalyptus,Leptospermum)Mimosaceae (Acacia)


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- diversiti alpha- kekayaan spesies dalam lingkungansesuatu habitat

- kekayaan spesiesdalam hutan atau payadsb

- diversiti beta

- perbezaan spesies diantara habitat

- perbezaan spesies diantara kawasan payadan hutan berhampiran

POLA-POLA DIVERSITI


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- diversiti gamma diversity

- perbezaan dalaman habitat, diantarakawasan(region)

POLA-POLA DIVERSITI


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POLA DIVERSITI


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Fitzgerald River NP


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Royal Hakea


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GENUS NUMBER of SPECIES

Acacia 400+Eucalyptus 300+Grevillea 200+Stylidium 150+

Melaleuca 150+Hakea 100+Caladenia 100+

there are some'centres of diversityor

diversity hot spots


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Fitzgerald River1750+ species

Mt Leseur820+ species

Stirling Range

Murchison Gorge


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plant

diversityhot spots


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Eucalyptus


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often have largeor showy fruits


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Banksia

26 21


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Verticordia


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Acacia


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In W.A. there is high ' -diversity' (gamma-diversity)

ie variation ACROSS the landscape

even relatively close areas havedifferent suites of species

how did this diversity arise ?


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EXPLAINING DIVERSITYvegetation types

forest

arid zone


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divide W.A. into three rainfall zones

HIGH

(800 - 1500 mm)

TRANSITIONAL(300 - 800 mm)

ARID

(< 300 mm)

decreasingrainfall


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forest


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Arid Zone


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nutrient poor soils

these are some of the least

fertile soils in the world(low P)

plants have evolvedmany adaptationsto be able

to compete

proteoid roots,symbiotic relationships

the landscape has barely changed since thePermian


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erosion of laterites resulted in mosaicofsoil types

typically laterite 'islands' in a sea of saline

valley floors


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adaptation to these nutrient poor soilshas resulted in'adaptive radiation'

(each species adopts a different survival strategywhich reduces direst competition)

some individuals have shallow extensive roots

some have deep roots

some exploit the surface to target brief rainfall

events

some have both deep roots and extensive shallowroots


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reducesdirectcompetition


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plants growing together have different survivalstrategies


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in the Transitional Rainfall Zone climatic changeresulted in significant rainfall fluctuations

mean !

high

rainfall

low

rainfall year


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FREQUENT and UNPREDICTABLE

environmental stresses for a long period

variable climatic conditions result in strong

selection pressure

strong selection pressure

results in high levels of speciation


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following a fire

CONDITIONS SEEDLING SURVIVALDrought 780 seedlings nearly zeroArtificial watering 90% survivalWet depressions 90% survival'Good' year 40% survival

strong selection acting on populations isolatedbysoil type (island effect)

results in different species on different soilislands


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SUMMARY

factors contributing to the development of high

diversity in W.A. are:

nutrient scarcityresult of long period of environmental

stability and leaching

geographic isolation (eg by arid Nullarbor Plain)mosaic of landforms and soils

(small scale isolation and island effect)


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cycles of strong selection pressure

following disturbances such asdrought, fire 'flush-crash' cycles


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so we can see that many of our ideasabout speciation are supported by this casestudy

read about some other well knownexample such as Darwins finches in the

references !!


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many species are now at risk of extinction due tofragmented habitat


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composition of roadside patches is very variable


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if we know that our biodiversity isdistributed across the landscape, no single

reserve can conserve all of the speciespresent in the region

every patch has a different suite of species

how many patches can we protect ?

with limited resources which patches willwe choose to protect ?

....see the prac exercises !!!!

L09- spesies baru

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