Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
31 Cards in this Set
- Front
- Back
|
Survival Strategy 2: Maximise water supply
|
Little or no water stress
drought escapers eg. desert annuals • water spenders eg. river red gums |
|
|
Survival Strategy 2: Buffer water supply
|
•water collectors eg. succulents (Opuntia) Baobab tree (Adansonia) One species in Australia • some very old • up to 15 m diam. • up to 100 kL water • fruit can be eaten |
|
|
Survival Strategy 3: Water-use-efficiency |
In C3 plants, CO2 diffuses through the stomata into the chloroplasts In most (C4) grasses, a CO2 pump can “suck” CO2 in through less open stomata, saving water |
|
|
Mulga – survival tricks |
Deep rooted •Drought deciduous •Water “catcher” •Pays protection (nectar) •Seeds dispersed by ants |
|
|
Sucrose-free sips good for Acacia ants |
Most ants prefer nectar with sucrose •Acacia nectaries contain invertase •Acacia ants have little invertase in guts – prefer low sucrose nectar Mulga seeds - shielded from fire Chamber depth - 100 C during fire Perfect pre-treatment for germination |
|
|
Xerophytes – water saving strategies |
Schlerophylly •Sunken, closed and partially closed stomata •Drought deciduous behavior •Leaf orientation and optics •Osmoregulation •High root: shoot ratio Reflective leaves, azimuth and angle •Water storage (succulents, baobab) |
|
|
Mulga – Ant Mutualism |
•Mutualism - the way two organisms of different species exist in a relationship in which each individual benefits •Myrmecophyte – plant that has a mutualistic relationship with ants •Nectar – protection from herbivores, fungi •Invertase – dedication (obligate mutualism) •Elaiosome (fatty food body on surface of seed) – seed dispersal/favourable (heat and nutrients) germination environment |
|
|
Australian Rainforests: Fruit |
•84% of 774 spp. of rainforest trees have fleshy fruits: •Birds disperse 97% of species (seeds < 2 cm in diameter) •Mammals and cassowaries disperse other 3% •Unlike any other rainforest |
|
|
Animals capable of dispersing large fruit: |
• cassowary • musky rat-kangaroo • white-tailed uromys • tree kangaroos |
|
|
Large fruit - an advantage: |
• resistance to predation • energy reserves for seedling establishment |
|
|
Cassowary |
Seeds from cassowary gut: 96% germination rate •No other treatment could do this •Vital vector for large seed dispersal |
|
|
Leaf Defence Strategies: Chemical Weapons |
Cyanogenesis: Production of toxic HCN gas from CN containing compounds in plant; identified in > 2000 plants; HCN inhibits respiration |
|
|
Structural adaptations of myrmecophytes |
(a) Extrafloral nectaries (e.g. mulga); (b) food bodies; (c) domatia |
|
|
Myrmecotrophy |
•Named after plants in genus Myrmecodia •Ability of plants to obtain nutrients from ants •Plants have tuber-like base inhabited by ants (chambers called domatia) domatia-a tiny chamber produced by plants that houses arthropods •Nutrients from ants (and rotting prey) are provided to the plant (special roots may grow into domatia) |
|
|
Mutualisms upon mutualisms: Ant Farmers |
Mutualisms upon mutualisms: Ant Farmers • Golden ants collect eggs of endangered Apollo Jewell Butterfly • Ants look after larvae, which enlarge domatia • Larvae also secrete syrup like substance which ants eat • Larvae pupate, hatch, fly away |
|
|
Australian Arid Zones 1. Climate - rainfall |
Arid: defined as insufficientrain for agriculture • Southern areas <250mm• Northern areas <500mm• Seasonality: wet & dry seasons, but timing differs in north and south Patchy: within districts& between years • Rainfall variationin arid Aust.: 10% higher compared to other arid zones around the world Result: rainfall unpredictable & thus availability of food also unpredictable |
|
|
1. Climate cont.: temperature extremes |
Up to 45C+during day Can reach freezing point at night |
|
|
Australian Arid Zones 2. Physiography (land “shape”) |
) Limited areas of ranges - only in Pilbara and central ranges (near Alice Springs), all <1500m (i.e. very low ranges)b) Vast flat areas (stony or sand), vast sand dunes & some low stony hillsc) Landscape highly weathered:= Low nutrients: N & P |
|
|
Australian Arid Zones |
Physiography & climate leads to low productivity (i.e. low plant growth) and therefore: •low food availability for animals • unpredictable food availabilityfor animals |
|
|
Animal survival strategies in arid zones |
Problems – poor soils – overall low food availability & often low quality – unpredictable water and food supplies – high temperatures (Jan/Feb >40ºC |
|
|
Solutions (strategies) |
Drought evasive: not active during dry periods – i.e. dormant stage as egg or adult, develop and reproduce rapidly after heavy rains, ORLeave drought areas |
|
|
Example of Drought-evasive strategies: |
Shield shrimp-Dormant as egg or adult during dry times • Eggs hatch & develop into adults very rapidly after rain • Incredibly fast life cycle (includes parthenogenic stages) • When puddles dry out eggs can remain in ‘suspended animation’ (diapause) for years. Eggs very tiny, can be dispersed by wind. |
|
|
Example of Drought-evasive strategies: 2 |
2. Migration in birds: e.g. budgerigars(arid zone distribution) •behaviour: migratory/nomadic – flockstravels up to 1500km to find food & water • Breed opportunistically when grass seeds become available after |
|
|
Drought-tolerant strategies |
Drought tolerant: often long-lived species - tolerate very low levels of moisture and food, behavioural strategies assist survival |
|
|
Examples of Drought-evasive strategies (e.g. insulate against extreme environment) |
Magnetic” termites • Mounds design reduces fluctuations in temperature N-S orientation • High humidity maintained within mound •Termites remain active during drought |
|
|
Drought-tolerant strategies -animals that remain active during dry times |
Honey pot ants • Live in highly unpredictable arid environment• Live underground, emerge to forage • Store food when it is abundant • Workers serve as storage pots to feed colon |
|
|
Drought-tolerant strategies:animals that remain active during dry times |
rid zone mammals • Endotherms, thus need to balance costs of thermoregulation with costs of water gain and loss • Must regulate temperature (e.g. via coat colour, evaporative cooling, behaviour etc.) • Avoid high temperatures (behaviour: nocturnal, burrow) • Water conservation |
|
|
Southern Hairy-nosed wombat |
Avoid high temperatures: - spend very little time above ground (use burrows)- Nocturnal • Relatively low metabolic rate (for a mammal) • Survive on low quality food i.e. pursues an energy conservation strategy |
|
|
One Endotherm strategy for coping with high temperatures in the arid zone: evaporative cooling |
When air temperature exceeds body temperature, evaporative cooling is only option •Sweating: generally too costly (mouse would lose >20% of body mass per hour) •Panting: primary mechanism for mammals <100kg •Saliva spreading:wiped onto fore and hind-limbs, subsequent evaporation cools the animal |
|
|
Maximising access to water -thorny devil (Moloch horridus) |
Specialised skin texture (morphology) to capture dew and rainwater • Scales are surrounded by tiny interconnected channels that attract water • Water is then funneled from these to the mouth |
|
|
Eyrean grasswren |
Physiology • Have very efficient kidneys – water retention • Don’t drink water at all • Extract water from dry seeds and small insects |
