Flora and Fauna

percentage of australian species enedemic

90%

Old explanation of southern hemisphere species correlations

long distance dispersal over waterways or land bridges that used to connect continents

Current explanation of southern hemisphere species correlations

Continental drift separating previously united land masses

Pangea break up

mid jurassic 160mya

Separation of continents from Gondwana

• NZ 80mya

• Au 35mya

• South America 30mya

Major climate determinants

• ocean and air currents

  Upwelling that brings cool, nutrient rich waters

  Wind currents bringing cool and warm airs from around the globe

• atmospheric chemistry

• topography

• latitude

Australia’s northward drift

• warm humid rainforests initially widespread

• shift in circumpolar current resulting in cooling Aus and contracting warm humid plant ranges

• desert expansion

• soil leeching during warm wet periods

• Laterite soil

• increased wind erosion - mobile dunes, drying lakes becoming salt planes

Laterite soil

thin or absent humus

thick masses of insoluble iron and aluminum oxides

occasional quartz

thick leached zone

manic ignious bedrock

low pH from oxidised iron results in optimum pH range for phosphorous

Pleistocene

2.5mya - present

Aus warm wet/cool dry periods with minimal glaciation due to flat topography

sand/silt mobilisation - dune formation

Edaphic barriers

soil land and climate conditions that effect flora and fauna

• sand dunes

• salt deposotion

• limestone formation

• makes it difficult for plants to extract nutrients and survive drought

Reproductive barriers

population isolation

adaption - speciation

Land use changes Aus

aridity reducing rainforest range

increase in fire incidence - charcoal and pollen in fossil record as evidence

Fire adaptations

• embedded stems

• locality

• leaf retention

• canopy seed storage

• soil seed storage

Closed forest

70-100% cover

can include closed scrub and closed heath

Open forest

30-70% canopy cover

can include open scrub and open heath

Woodland/shubland

10-30% canopy cover

low to tall woodland = 5m and above

shrubland = 0-8m tall

open woodland/shrubland

less than 10% canopy cover

Human landscape use

clearing land

increased closed forest instead of open forest

fuel/fire intensity increased

cropping resulting in open areas with changed flor and fauna

paddocks open grassland but with introduced grass species

Rainforests

high diversity

high endemism

tropical to temperate

high rainfall

surviving remnants of gondwanan flora and fauna

high conservation area - NE QLD wet tropics world heritage area

many species have medicinal values

Assisted migration

dispersal of seed sources or populations to locations far outside the historical species range and beyond locations acessable by natural dispersal

tropical rainforest

lowland

most species rich (eg. up to 1000 beetle species per tree)

100-200 tree species per hectare

ferns and palms

trees with large leaves (>12.5cm)

high rainfall - high humidty, saturated soils, soil leeching

pathenogenic organisms often thrive

high solar radiation

Temperate rainforest

fewer species

fewer layers, simpler structure

smaller leaves (2.5-7.5cm)

cool temperate rainforests

open forests with lower canopy cover

Lowland tropical rainforest

climate uniformly warm and wet

rainfall >1800mm

elevation <1000m

rapid water and nutriet cycling - rapid growth

regional differences in composition

Wallaces Line

separates 2 distict faunal regions

• Indo-Malaysian

• Austro-Malaysian

combination of plate tectonics and climate

climate intolerance prevented a lot of species migration to Australia

Leaf adaptations to rainforests

morphological - large, leaves, drip tips, waxy, hydathodes

physiological - guttation, sun leaves bigger than shade leaves, adapted to light gaps (sunflecks) which have high light in short intervals - dynamic photosynthesis

compound leaves

Guttation

mores on leaf edge drip water

foot pressure drives water up the plant

excess water availability adaptation

Compound leaves

large surface area

divided into leaflets

capture light but allows penetration to lower branches

cheaper to produce than branches

tropical root adaptaions

shallow roots - rapid litter turnover, leeching, saturation

buttress roots - shallow, structural support, improves competitive ability to access light and nutrients, stabilises soil and erosion control

prop roots - shallow, structural support, improves competitive ability in height and lateral expansion, stabilises soil

Shoot/stem adaptations

Climbing habit (lianas) - access to light, respond to disturbance, abundant in tropics, maintain diversity through competition - more species rich in rainforests, perform better during disturbance due to higher light, can overshade other species

Thorns and prickles - defence

Modified trichomes - epidermal structures, environmental sensory, fluid filled, silica enriched, needle shaped and resemble felt hairs, eg. stinging netals

Cauliflory - flowering on woody stems where polinators have easy access, increases seed dispersal by birds - mutualism/symbiosis

Lianas

climbers

higher species richness in rainforest

function best during disturbance as can access more light

can overshade other species

Cauliflory

flowering on woody stems where polinators have easy access

increases seed dispersal by birds

mutualism/symbiosis

Epiphytes

rainforest

plants growing on another

acess to light without investing in stems or rapid growth

no access to soil so rely on host for nutrients and water

often xerophytes and mycorrhizae

commensalism

elkhorn and staghorn ferns - 2 leaf types - one nest leaves which collect litter

basket ferns - 2 leaf types - fertile foliage fronds (senesce) and sterile nest fronds (often brown)

Parasitic plants

rainforest

overcome need to access light by tapping into photosynthate, often lacking roots leaves or stems

parasitism

particularly evolved when resources are limited

strangling fig

rainforest

starts life in upper canopy as an epiphyte and then crushes host

seeds dispersed by birds

commensalism then parasitism

Carnivorous plants

rainforest

6 orders, 11 families

evolved independently - convergence

Australia~ 200 species

low nutrient environments

pitcher plants - trap insects inside modified leaf

Rainforest dispersal

>80% tropical fruits brightly coloured and fleshy

few large fruits

fruits in nutrient high areas

small birds disperse 97% fleshy fruited species (seeds <2cm diameter)

mammals and cassowaries disperse other 3%

frugivores

other animals such as musky rat kangaroos, white tailed uromys, tree kangaroos

Frugivores

cassowary, wompoo fruit dove, flying fox, bowerbirds, figbirds

animals which survive mostly on fruits and succulent like produce

large seeds/ fruits advantages and disadvantages

Advantages

• resistance to predation

• energy reserves for seedling establishment

• evolved in resource poor environments with ample water

disadvantages

• reduced mobility

• increased apparency - large energy resource

Cassowary

largest vertebrate in Australian rainforests

only animal capable of long distance seed dispersal

up to 2m tall

10-13 cm claw on inner toe

aids in germination of seeds including toxic ones

can carry large seeds and large volume of seeds

large home ranges

Phytochemistry

secondary metabolites diversified/intensified with high selection pressure

ripe fruits have fewer toxins and are attractive

avoiding HCN by defecating in 3-4 hours and via coevolution with different enzymes and products

Green ant plant mutualism

and bends leaves to make a nest and in return attacks predators

lipid bodies reduce nitrogen for the ants making them more agressive towards other organisms that are destructive to the plant

Plant naming ending

-aceae

eg. Ericaceae

animal naming ending

-idae

eg. Macropodidae

Non flowering australian species

bryophytes

ferns and allies

cycads and conifers

oldest species

all major non flowering lineages present in pangea

Angeosperms

large majority of australian flora

flowering plants

Byrophytes

moist areas

can form biocrusts - arid areas

contribute to water retention in arid areas via nucleation and evaporation reduction

desiccation and rehydration of mosses and greatly increases resource flux whcih contributes to carbon and nitrogen cycling

mosses and ferns

pops in Au, NZ and PNG/indonesia show little morphological or genetic variation

spores

Cycads

one of earliest seed plants

all in Aus are endemic

all dioecious - separate male and female plants

widespread at various times

no australian fossil record - suggests new arrival

ancient lineages with global distribution

Dioecious

separate male and female plants

Conifers

pines

Huon pines are oldest individuals dated to 3500 years

44 species , 39 endemic

fossil record suggest substantial contraction and extinction in most lineages

Proteaceae

legumes

bottle brushes, gravilla, acacia

high diversity in shape

molecular, genomic and morphological data to trace lineages

floral organs established in concentric layers (whorls)

angiosperms - lineages of plants with vessel containing seeds

flowers can be male or female or both

flowers can be complete (all whorls) or incomplete (missing a whorl - one gender)

monoecious (“single house”) - if male and female flowers occur in same plant

Dioecious (2 houses) - male and female flowers in different plants

outermost floral organs are non reproductive

low nutrient areas - banksia, gravilia

rainforests - macadamia, warratahs

clustered roots

diversity associates with low phosphorous

many seeds open after fire

Staminate flowers

male flowers

Carpellate flowers

female flowers

Gravillia

4 lobed perianth

4 stamens attached to tepals

ovary 1 or 2 compartments

style long and acts as pollen presenter (male phase) and then receives pollen (female phase)

anther releases pollen onto style when folded

pollen placed on birds head while feeding on nectar

Pollinators

sensitive to different wavelenths

honey eater tounges shapped differently

Aussie legumes

many have toxins that must be removed by toxins

peas - trees, shrubs, herbs, creepers, climbers

hard resistant coats - survive fire

often compound leaves

schleorophyll forms simple leaves, reduced to spines or scales

nitrogen fixing

colours and size associated with polinaots

peas, cassias, wattles

Acacia

waittles

largest genus of woody flowering plants in Aus

rainforest and wet eucalypt forest

dominant in semi-arid and arid regions

keystone species

high protein and carb content in many

nitrogen fixing - key species in fire recovery

bipinnate and phylathode leaves

Bipinnate leaves

compound leaves that grow opposite to each other on a stem

double/twice compound leaves

Myrtaceae

3000 species worldwide

bottlebrushes, teatrees, paperbarks, lilly pillies and eucalypts

have fruits

gondwanan group

most have leaves with aromatic oils - highly flammable

anti-herbivory - thorns and spines

most common fruits are eucalypt capsules - open by valves - dry fruited forms

fleshy fruited forms - rainforest lilly pilly

flowers have radial symmetry. 4-5 sepals, 4-5 petals, many stamens

polinated by flies, beetles, bees, birds, honey possums

Anti-herbivory

thorns and spines

Drought avoiders

annuals/ephemerals

spend dryer times as seeds

water presence triggers seed germination - grow quickly once water is available

deep root system to access ground water

funnel like leaf system to direct rain water to land on roots

inactive during dry periods

migration or dormancy

hermaphroditism makes breeding quicker and easier

Xerophytes

drought tolerators

schlerophylls

succulents

Schlerophylls

• tough rigid leaves

• more common than succulents in aus

• acacias - dominant vegetiation in deserts

• often small leaves and short internodes

• reduced SA:V on leaves

• thick waxy cuticle

• sunken stomata

• lead hairs

• thick walled cells - lignin in walls

• leaf rolling in grasses

• evolved in low phosphorus areas - Beadles hypothesis

• evidence before onset of aridity in Aus

Evolution in low nutrient areas

lack of nutrients can limit cell growth and metabolism

macronutrients - C,N,P

P critically important for nucleic acid backnones

slow growth, small leaves and internodes, lignin, thick cell walls

more efficient nutrient use

succulents

• chenopodiceae - saltbushes

• fleshy plants, large cells filled with watery sap

• draught and salt tollerant

• silvery folliage - salt crust

• surface colour reflects radiation

• covered in bladder cells to excrete salt

• arid Aus lacks large stem succulents

• Boab tree

• Prickly pear - introduced invasive species

• low SA:V raito

• shallow roots

• CAM for many

• cortext and pith store H2O

CAM

Crassulacean Acid Metabolism

succulents

pinapple, aloe, orchids

38 angiosperm families

7% vascular plants

air plants

open stomata at night

can be switched on/ off

idling can occur under extreme stress - stomata always closed

Obligate CAM

plants that always perform CAM

independent of other conditions

Facultative CAM

CAM expression depends on environmental and or developmental cues

eg. pinapple and other bromeliads

CAM idling

extreme stress

photosythesis just uses CO2 from respiration

no growth only maintenance

C3

rubisco

PGA is 3 C compound that sugar is first converted into

Photorespiration

O2 instead of CO2 being fixed

reduces photosynthesis efficiency - particularly at high temps

C4

subtropical and tropical plants

many grasses - 23% global grass productivity

australia has highest c4 dominance of all continents

C4 have higher affinity for CO2

pep carboxylase acts as pump and concentrates CO2

Staying wet

H2O evaporation used as cooling via latent heat loss

H2O needed for cellular finctioning, metabolism, maintaining turgor, nutrient transport and photosynthesis

Staying cool

adapted to different temp ranges

metabolism reliant on different enzymes

high temps can lead to irreversible denaturation

sensible heat, net radiation load and latent heat

Sensible heat

heat loss

eg. from warmer leaf to cooler air

Flux = Gh(Tl-Ta)

Tl= leaf temp

Gh = conductance to heat

the bigger the difference between air and lead temps, the greater the sensible heat flux

heat you can feel

Net radiation load

Solar + heat from surroundings

latent heat

heat loss from evaporation of H2O

Flux + Gw(Wl-Wa)

Wl= water vapourconcentration leaf

bigger difference in air and leaf water vapour concentrations

Gw = conductance to water vapour

latent heat loss dependent on stomatal aperture and difference in H2O vapour concentrstion

Kangaroo heat loss stratergies

move to shade

promote latent heat flux by lcking forearms - cools blood in vessels close to surface

promoted sensible heat loss by laying on cool soil - digging into it

Plant heat loss stratergies

Leaf orientation

• vertical foliage reduces radiation load - eg. eucalypts

• adjusting leaf orientation during day - diaheliotrophic and paraheliotrophic

smaller or larger leaves - smaller in high sun

leaf shape - needles have low SA:V, leaf rolling can be rolled and unrolled depending on time of day

leaf amount - low lead weight relative to rest of plant, drought deciduous

leaf optics - silver grey foliage, saltbushes (bladders accumulate salt concentration and then burst), increasing reflectance

increasing water storage

C4 photosynthesis pathway to conserve water

Fire incidence change

burning levels increased since around 15mya

relative importance of vegetation types has changed - rainforest has declined

increased particularly in holocene

properties of bushfires

intensity dependent on:

• time of year (temp)

• amount of fuel

• fire is hotter if there is more accumulated flammable material

Survival determined by:

• temp fire reaches

• length of time exposed to heat

• critical temperatures - cells, tissues, proteins damaged at >60%

Schlerophyll adaptations to fire

flowers stimulated by fire

oil in leaves promotes faster and cooler fires

adult plant killed but seeds survive - post fire re-sprouting from dormant buds

canopy and seed banks

thick, fiborous outer bark - protects living parts such as vascular cambium

dormant buds - aerial epicormic buds (growth suppressed when canopy intact and promoted by hormone change when canopy lost), underground buds (lignotubers, rhyzomes, root suckers)

banksia and hakea - thick, woody seed shells, canopy seed bank, seeds from woody fruits released when dehisced

soil seed banks

seeds have elaiosome which provides food reward for ants

seed dispersal by ants - myrmecochory

smoke releases compound which stimulates germination

Lignotubers and Rhyzomes

dormant buds underground which allow gum regrowth

snow gums

elaiosome

fleshy funicle on seeds which provide food source to ants which in turn disperse seeds and bury them in their nest

Myrmecochory

seed carrying partnership between ants and plants

grass tree fire adaptations

Xanthorrhoea and Kingia

smoke contains hormone that stimulates flowering

influx of nutrients to soil after fire in the ash bed (particularly phosphorous)

fire reduces competition

resprout leaves from trunk after all foliage burnt by fire

Fire impact on forest type

if it has been over 200 years without fire northofaus dominates due to slower growth

frequent fires have resulted in geater proportions of mountain ash forests

Fire diversity curve

Australian arid zones

wide variety of topography

arid zone expanding

defined as insufficient rain for agriculture

arid <250mm

semi arid <500mm

highly irregular and unpredictable rainfall and patchy within districts and years

temp extremes - 45+ in day and can reach freezing at night

vast low areas

highly weathered and low nutrient environment

Arid animal habitats

hills and caves provide refuge - yellow footed rock wallaby

cracking soils provide refuge for small animals - planigale

stony desert of “gibber plain” is like polished rocks from wind - very little refuge

sandy dunes are moveable - level of plant cover impacts mobilty

vast flat areas have grasses which provide cover and seeds

aestivation

drought evasive

lower their metabolism and remain inactive

Drought tolerant

insulate against extremes such as temp or water

endotherms - need to balance costs of thermoregulation with costs od water fain and loss

burrowing

nocturnal

lowering metabolic rate

ectotherms have lower water requirement

specialised skin textures for water loss and capture

efficient kidneys

Alpine

alpine zone gets snow but not all year round

australia has no nival zone

0.15% Aus landmass

mean temp of warmest month <10c

snow 2-3 motnhs

strong winds

highly fragmented

predictable weather patterns

Snow gums

waxy leaves - withstand freezing

not on mountaintops

short and slow growing

highly susceptable to fire

lignotubers

changes occuring to alpine zone

tree line continually increasing

adapted animals pushing higher due to warming

18-66% reducting in snow cover by 2030 - up to 70% by 2070

tops of 6 mountains will be only remaining alpine ecosystems

Alpine Fauna charactaristics

low diversity

fewer species present as altitude increases

no truely alpine birds - migratory

low reptile diversity - one species (alpine skink) found over 2000m

very few mammals and largest herbivores absent

invertebrates most diverse group

highly seasonal food availability

Alpine ectotherms

STRATERGIES: dormant life stage, migration, behavior such as seeking refuge

small

Stenothermic - physiology adapted for narrow range of low temps, produce anti freeze, sensitive to heat

reduced wings

tasmanian scorpionfly - larvae active in winter and consume moss, so temp sensitive can die in hand

chameleon grasshopper - active during the day, thermal malanism - in cold colour is darker and in warm becomes lighter

corroboree frogs - males dig burrows in sphagnum moss where females lay eggs, eggs triggered to hatch when snow melt wets burrow, development delayed till late winter

Stenothermic

physiology adapted for narrow range of low temps

common in alpine ectotherms

produce anti freeze

sensitive to heat

animals that live in very stable conditions with a narrow temp range

Thermal Melanism

changing colour due to temperature

eg. grasshoppers in alpine areas becoming darker in winter to absorb more heat from sun and lighter in summer

Alpine Endotherms

mammals and birds

migratory

torpor - daily adaptive hypothermia

• decreased body temp

• reduced rates (metabolic, respiratory, heart)

• curl up to minimise surface area

• small species (adults <10kg)

• often response to food availability

wombat - larger size means less heat loss, dig under snow to reach food

hibernation

• seasonally-induced torpor

• mountain pygmy possum

• echidna

• fatten up prior to winter

• periodical arousal