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31 Cards in this Set
- Front
- Back
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Australian alpine zone |
• 0.15% of Australian landmass • Mean temp. of warmest month <10oC (trees don’t thrive)• Snow 2-3 months per year • Strong winds • 25% of Australia's rainfall •Significant area for: water supply, recreation, nature conservation (contains unique group of native species |
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Special features of the alpine environment: predictable, strongly seasonal |
xtreme temperature differences • Prolonged cold - winter, night and cloud • Abundant moisture - condensation, snow melt • Flora mostly herbs and lichens- very low biological productivity • Snow gums (sub-alpine woodlands) • Energy input through flying insects, wind-blown detritus, pollen and seeds |
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Snow gums (sub –alpine) |
Leaves can withstand freezing (waxy) • Do not occur on mountaintops (not in alpine zone) • Highly susceptible to fire |
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Australian alpine zone fauna |
Low species diversity • Fewer species present as altitude increases • No truly alpine birds - migrate seasonally e.g. flame robin • Low diversity of reptiles (only 1 species found over 2000m in altitude) • Very few mammals, largest herbivores absent •Invertebrates most diverse and abundant group! • Experience highly seasonal food availability |
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Ectotherms (don’t maintain high Tb via metabolism) in the Alpine zone: |
Lower energy requirements – useful in an energy poor environment • However Tb declines with environmental temperatures, thus can’t maintain activity •Strategies to avoid freezing??- dormant life stage- seek refugia- migrate |
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Alpine invertebrate adaptations for coping with considerable temperature fluctuations |
mall size (hypolithy - occupy sheltered micro-climates e.g. under rocks)• Stenothermy (physiology geared to operate at low temps thus sensitive to heat)• Reduced wings (flying difficult in high winds if body mass is very low) |
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Invertebrates: behavioural thermoregulation |
Chameleon grasshopper (Kosciuscola tristis) • Remain active all day (can cope with temperature extremes) • Movement in & out of sun • Thermal melanism:- in cold conditions (higher altitude)darker/black, thus absorb heat- in warmer conditions (lower altitude) – paler blue or green |
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Frogs in the alpine zone! |
Over-winter in alpine areas (low mobility) • Become totally inactive • Must find microhabitats that don’t freeze |
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Corroboree frogs |
Occur mainly over 1800m elevation • Males dig burrow in sphagnum moss bogs & call • Females lay in this nest • Eggs hatch, but development is delayed until winter, then slow. When burrows fill with water in spring they mature |
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Endothermic animals: |
Endotherms generate their own body heat via metabolism (i.e. maintain Tb within strict limits ) but this is very energetically expensive - mostly occurs in mammals and birds Alpine endotherm strategies: • Migratory: many sp. avoid cold by migrating - e.g. birds, large mammals (wallabies) • Permanent residents- some sp. stay active- some use torpor |
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Torpor – daily adaptive hypothermia |
• Body temperature drops dramatically • Reduced metabolic rate, respiratory rate, heart rate, body temp • Curl up (minimise surface area) • Often a response to low food availability • Very important in seasonal and low productivity habitats • Small endotherms – never more than a few hours fromstarvation • Occurs in species where adults <10kg • Common among small marsupials • Energy-saving strategy |
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Torpor in a mammal |
• MR at 1/20 - 1/100 normal, thus saves large amount of energy (thus reduces food requirements) • Animals exit torpor by turning MR up, body temperature follows • can be short-term or long-term |
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Hibernation: Seasonally-induced deep torpor, longer bout |
Only two Australian mammals:- Mountain pygmy-possum - Echidna •Fatten-upprior to winter • Hibernaculum (safe place) • Test drops in body temp • Periodic arousal |
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Breeding patterns in alpine zone animals |
Short period of warmer weather, thus short growing season & short breeding season, but very predictable(unlike in arid zone) • Some species exhibit dormancy at other times of year (i.e. during non breeding season) • Invertebrates: speed of development often not as crucial as in arid areas. Life-cycle usually completed in a season. • Larger animals, e.g. Mountain pygmy-possum -synchronised breeding season, fast growth etc |
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Bogong moth (Agrotis infusa) |
Larvae winter in pastures in Sth QLD, NSW & SE Vic, but food plants dry over summer • Intolerant of summer heat • Adults migrate to alpine areas, shelter in caves & crevices >1500m during spring/summer up to 17 000 individuals/m2 • Aestivate when in alpine zone -survive on fat stores |
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Constraints for research in tropical rain forests |
Remote * often logistically difficult *wet season flooding and isolation |
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Petaurid possums |
Plant exudates (sap, gum, nectar)a major component of diet* Smaller species supplement dietwith invertebrates |
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Unusual morphological characters of Striped Possums |
Klinorhynchy (rounded cranium)
* Large procumbent lower incisors * Tongue & 4th finger elongated Prediction:that striped possums are insectivores & will therefore require much larger areas of habitat than other petaurid possums |
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Why do tropical rainforests support high animal diversity? |
-patchiness (potential speciation) -high complexity -high productivityy |
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Australia’s tropical rainforest Fauna links with PNG & Asia cont |
Mammals Little Red Flying Fox:Flying foxes highly mobile, capable of long distance movements.Effectively one large population in Aust & PNG |
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Reptiles |
Ring-tailed gecko Amethystine Python:Australia’s largest snake (to 8m), major predator in rainforest Reptiles e.g.s:no migration, thus PNG & Australian pop.ns now isolated: Torres Strait = current geographic barrier |
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Geographic or habitat barriers
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can lead to population divergence over time: potential for speciation to occur |
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Endemic species |
Unique to a particular geographic region or locality, assumed to have evolved there. Large number of endemic species in Australian tropical rainforest, therefore should be given high conservation status if under threat. More endemics at higher altitude |
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Rainforest endemic |
Boyd’s forest dragon: little knowledge of biology, occurs in very dense rainforest areas, distribution: high & low altitude |
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Rainforest endemic |
Orange-thighed frog: little knowledge of biology, only recognised as a distinct species in 1986 |
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Conservation: key issues for endemic species |
-limited distribution often habitat specialists(loss of habitat or population = loss of that species world wide) - often rare & difficult to study, often little knowledge of biology |
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Key conservation issue: loss of biodiversity |
41. Habitat loss:extensive clearing of tropical rainforest is a direct threat to fauna e.g. Ulysses Butterfly |
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Key conservation issue: loss of biodiversity |
2. Impact of indigenous hunters: increasing human pop. & development, along with continuing traditional hunting |
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Key conservation issue: loss of biodiversity |
3. Poaching: Wealthy animal collectors drive poaching of rare species for their private collections |
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Key conservation issue: loss of biodiversity |
4. Disease:Sharp-Nosed Torrent Frog (G: Taudactylus) threatened bychytrid fungus |
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Early vs. recent arrivals |
e.g. mammals: Australian native rodents originated in Asia (i.e. relatively recent arrivals), musky rat kangaroo a Gondwana group -involved in seed dispersal -Contribute to forest regeneration and ecosystem health |
