Lecture 16- Marsupials: Koala

Question 1

What class are the koalas in?

Answer 1

Mammalia

Question 2

What subclass are the koalas in?

Answer 2

Theria

Question 3

What infraclass are koalas in?

Answer 3

Marsupialia

Question 4

What order are koalas in?

Answer 4

Diprotodontia

Question 5

What suborder are koalas in?

Answer 5

Vombatiformes (wombats and koalas)

Question 6

What family are koalas in?

Answer 6

Phascolarctidae

Question 7

What is koala’s distribution?

Answer 7

• approx. 1 million km squared
• approx. the area of Japan
• koala is not a species most at risk
• coastal East Australia

Question 8

What is koala habitat like?

Answer 8

-forests, Eucyalyptus woodlands, containing preferred Eucalyptus species

Question 9

What is ranging behaviour like in koalas?

Answer 9

• adults are sedentary
• have small ranges (in SE Australia)
• larger home ranges in dryer areas in the north

Question 10

What do koalas eat?

Answer 10

• Eucalyptus leafs,

- species depends, can eat more than one

Question 11

Why is it surprising that koalas are arboreal?

Answer 11

• no tail!

- large body size (males up to 15kg which is the approx. upper limit for arboreals)

Question 12

How are koalas adapted to arboreal life?

Answer 12

• excellent climbers
• claws and feet adapted for climbing
• can jump sometimes but not that good at it and dangerous

Question 13

How did koalas become arboreal?

Answer 13

• secondarily arboreal

- wombat and then went up

Question 14

What is the koala diet?

Answer 14

• specialist folivore, feeds almost exclusively on foliage, from a limited number of (mainly) eucalypt species, these vary regionally
• sometimes feed on peppermint

Question 15

Why are koalas not very active?

Answer 15

-foliage is poor quality diet, hence not very active

Question 16

What are the constraints on herbivore digestion?

Answer 16

• structural plant material is hard to digest (cellulose) is difficult to digest
• dependent on bacterial and protist cellulases (diverse protist and bacterial microfauna in the gut-symbiotic microorganism)
• food preparation: fine particles

Question 17

How do koalas prepare the food they eat?

Answer 17

• cutting molars (4 cusps on each), they cut, chop the leaves, older koalas
• then less efficient digestion (worse surface to area ratio), die of starvation eventually

Question 18

What are secondary metabolites in plants?

Answer 18

• chemicals that help plants resist herbivores
• anti-feedants
• vary between species (phenolics=tannins, terpenoids=essential oils)
• secondary= because no know primary function in the plants

===species need to be physiologically specialised to feed successfully on such plants

Question 19

What are the tactics to deal with plant secondary metabolites (PSMs)?

Answer 19

• avoidance
• dilution
• degradation
• detoxificantion

Question 20

What is the importance of nitrogen in home ranges?

Answer 20

PSMs limit nitrogen available to animals= low reproductive success and habitat selection

Question 21

How are PSMs deactivated/detoxified?

Answer 21

• absorption from gut then conjugation in liver (via microsomal enzymes, endoplasmic reticulum), water soluble conjugates are excreted in urine (kidney) or bile (gut)
• urine smells like eucalyptus

Question 22

When do koalas mate?

Answer 22

• spring- summer

- November to March

Question 23

How long is pregnancy?

Answer 23

35 days

Question 24

How many young per year?

Answer 24

1, (some populations breed more slowly due to chlamydia)

Question 25

How long is lactation in koalas?

Answer 25

12 months

Question 26

What is the juvenile survival like?

Answer 26

-high

Question 27

When are koalas sexually mature?

Answer 27

at 2 years of age

Question 28

How does koala weight change due to lactation?

Answer 28

- weight loss in late lactation due to high energetic load coupled with low quality food - they carry the baby on their back, costly energetically - they drive the baby off when new one in the pouch

Question 29

How do males and females differ?

Answer 29

- males much larger than females - care of young is maternal only - males fight - males bellow - males scent mark = chest gland= rub it on trees to mark territory

Question 30

What do males bellow for?

Answer 30

deep and loud, signal to females to know where the males are | -also tells other males where they are

Question 31

Why do many males fall off the tree?

Answer 31

males fight, common in dense population | -the males fall off the tree, mostly when 3.5 yrs old when trying to get into the breeding population

Question 32

What is the morphological change in characters across a species geographical distribution (latitudinal cline) = gradual change in characteristics from north to south?

Answer 32

- fur length or thickness - colour - body size - shape

Question 33

What is Bergmann's rule?

Answer 33

-medium to large sized mammals with large distribution usually exhibit larger body size in colder areas (shorter ears, to conserve heat)

Question 34

What is the morphological cline in koalas?

Answer 34

- north: shorter paler fur, adult males up to 9.1 kg (most 7-8) - south: longer darker fur, adult males up to 15kg (most 11-12.5kg) - large body size an advantage for males in fights

Question 35

What are the problems koalas face?

Answer 35

- differs from place to place - cyclones= trees defoliated, drought= trees defoliate - wild dogs hunt them (ones that ran away from people) - habitat destruction and fragmentation due to human inhabitation

Question 36

Why are some koala populations declining?

Answer 36

- habitat loss and fragmentation= land clearing and urbanisation - increased mortality (cars and dogs) - low fertility (chlamydia) -happens when mortality is larger than recruitments= then population decline

Question 37

Why are some koala populations increasing?

Answer 37

- high fertility, rapid population growth | - occur in habitat isolates (like reserves etc,.)

Question 38

What are the management techniques for overpopulated koalas?

Answer 38

- relocation to other habitats so they don't kill their food trees) - fertility control=hormone implants for females= very effective and do not harm the animals - habitat protection and restoration

Question 39

What type of digestion do koalas have?

Answer 39

- -hindgut fermenters, have gut 6-7 long | - long gut passage time= as need time to digest