Lecture 12

Question 1

Australia is the _____ driest continent on Earth.

Answer 1

second

Question 2

What are the two predominant features that impact animals?

Answer 2

• Climate

- Physiography (“shape of land”)

Question 3

The north of Australia receives ______ rainfall, while the south receives ______ rainfall.

Answer 3

summer; winter

Question 4

An ‘arid’ climate is defined as having insufficient _____ for _______.

Answer 4

rain; agriculture.

Question 5

How much rain does a southern area in Aus need in order to be considered ‘arid’?

Answer 5

<250 mm

Question 6

How much rain does a northern area in Aus need in order to be considered ‘arid’?

Answer 6

<500 mm

Question 7

What proportion of Australia is considered arid or semi-arid?

Answer 7

70%

Question 8

Rainfall in Australia’s arid zones is _____ and __________. (10% more variation compared to other arid zones around the world.

Answer 8

patchy; unpredictable.

Question 9

After rain in arid areas, there is rapid _____ growth, meaning that food for animals greatly ______.

Answer 9

plant; increases.

Question 10

In arid parts of Australia, the temperature can reach up to ___ degrees during the day and reach _____ _____ at night. There is no ______ layer to trap warmth.

Answer 10

45; freezing point; boundary.

Question 11

List 3 main features of Arid Australia’s physiography.

Answer 11

• vast flat areas (vast sand dunes and some low stony hills)
• limited areas of ranges (and they are very low ranges) (Pilbara and central ranges near Alice Springs).
• highly weathered landscape (low in N and P)

Question 12

Cracking soils provide _______ for _____ animals.

Answer 12

refuges; small.

Question 13

A gibber plain is a stony desert that contains rocks high in ______ that do not _______ easily.

Answer 13

silica; weather

Question 14

In the vast, flat parts of arid Australia there are sometimes large areas of _______ grasses such as _______. In these areas there is an _______ in biodiversity. This is because the grasses provide both a ___-________ and _____ for animals.

Answer 14

Hummock; Triodia; microhabitat; food.

Question 15

The physical geography and climate of arid Australia leads to two main challenges for animals. What are they?

Answer 15

• low food and water availability for animals

- unpredictable/highly variable food and water availability for animals.

Question 16

Mammals and birds are ____thermic.

Answer 16

endo.

Question 17

Reptiles and frogs are ____thermic.

Answer 17

ecto.

Question 18

Invertebrates (for example, ants and termites) are small, _____thermic and have ______ total energy requirements than vertebrates.

Answer 18

ecto; lower.

Question 19

Animals in arid Australia can employ drought-______ strategies or drought-_______ strategies to deal with the challenging climate (or a combination of the two).

Answer 19

evasive; tolerant.

Question 20

Drought-evasion strategies include:

• remaining _______ as an egg or an adult during ____ times.
• breeding _______ after rain (when water and/or food becomes available).
• _______ (e.g. budgerigars)

Answer 20

dormant; dry

rapidly

migration

Question 21

What drought-evasion strategies do burrowing frogs such as Cyclorana employ to survive in arid Australia?

Answer 21

• dormant as adult
• water conservation via aestivation (lowering of metabolic rate and remaining inactivate) and cocooning (to store water)
• emerge an breed rapidly after rain

Question 22

Drought-tolerant animals are often ____-lived species which tolerate very low levels of ______ and _____ due to physiological adaptations. They often have _________ strategies to assist survival.

Answer 22

long;
water; food
behavioural

Question 23

When the air temperature exceeds the body temperature of a mammal, it will begin to employ ____________ _________.

Answer 23

evaporative cooling.

Question 24

List 3 forms of evaporative cooling

Answer 24

• sweating (not usually sustainable)
• panting (primary mechanism for mammals less than 100 kg in weight)
• saliva spreading (wiped onto forelimbs and subsequent evaporation cools the animal)

Question 25

Water requirements for ectotherms are _______ than for endotherms. Note, however, that only a small proportion of endotherms in arid Australia need to ______ because they are arid __________. Probably no reptiles or invertebrates need to _____.

Answer 25

lower; drink; specialists; drink

Question 26

Arid zone mammals must regulate their ___________.

Answer 26

temperature.

Question 27

Arid zone mammals must balance costs of _______________ with costs of water _____ and ____.

Answer 27

thermoregulation; gain; loss.

Question 28

Describe the ways in which Honey pot ants are drought-tolerant.

Answer 28

• live underground where the temperature and humidity is less extreme.
• emerge from underground to forage
• ‘replete’ workers store food (as a sugary syrup) in their rear end when it is abundant and the colony feeds on these storage pots in the cooler underground conditions

Question 29

How does the thorny devil maximise access to water?

Answer 29

• specialised skin texture captures dew and rainwater
• its scales are surrounded by interconnected channels that attract water
• channels lead to mouth meaning that water is funneled in.

Question 30

How does the Eyrean grasswren deal with low water availability?

Answer 30

• very efficient kidneys assist in water retention

- does not drink but instead extracts water from dry seeds and small insects