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BSC Zoology - Australian Wildlife > Lecture 16- Marsupials: Koala > Flashcards

Lecture 16- Marsupials: Koala Flashcards

1
Q

What class are the koalas in?

A

Mammalia

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2
Q

What subclass are the koalas in?

A

Theria

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3
Q

What infraclass are koalas in?

A

Marsupialia

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4
Q

What order are koalas in?

A

Diprotodontia

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5
Q

What suborder are koalas in?

A

Vombatiformes (wombats and koalas)

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6
Q

What family are koalas in?

A

Phascolarctidae

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7
Q

What is koala’s distribution?

A
  • approx. 1 million km squared
  • approx. the area of Japan
  • koala is not a species most at risk
  • coastal East Australia
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8
Q

What is koala habitat like?

A

-forests, Eucyalyptus woodlands, containing preferred Eucalyptus species

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9
Q

What is ranging behaviour like in koalas?

A
  • adults are sedentary
  • have small ranges (in SE Australia)
  • larger home ranges in dryer areas in the north
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10
Q

What do koalas eat?

A
  • Eucalyptus leafs,

- species depends, can eat more than one

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11
Q

Why is it surprising that koalas are arboreal?

A
  • no tail!

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

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12
Q

How are koalas adapted to arboreal life?

A
  • excellent climbers
  • claws and feet adapted for climbing
  • can jump sometimes but not that good at it and dangerous
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13
Q

How did koalas become arboreal?

A
  • secondarily arboreal

- wombat and then went up

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14
Q

What is the koala diet?

A
  • specialist folivore, feeds almost exclusively on foliage, from a limited number of (mainly) eucalypt species, these vary regionally
  • sometimes feed on peppermint
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15
Q

Why are koalas not very active?

A

-foliage is poor quality diet, hence not very active

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16
Q

What are the constraints on herbivore digestion?

A
  • 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
17
Q

How do koalas prepare the food they eat?

A
  • 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
18
Q

What are secondary metabolites in plants?

A
  • 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

19
Q

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

A
  • avoidance
  • dilution
  • degradation
  • detoxificantion
20
Q

What is the importance of nitrogen in home ranges?

A

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

21
Q

How are PSMs deactivated/detoxified?

A
  • 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
22
Q

When do koalas mate?

A
  • spring- summer

- November to March

23
Q

How long is pregnancy?

A

35 days

24
Q

How many young per year?

A

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

25
Q

How long is lactation in koalas?

A

12 months

26
Q

What is the juvenile survival like?

A

-high

27
Q

When are koalas sexually mature?

A

at 2 years of age

28
Q

How does koala weight change due to lactation?

A
  • 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
29
Q

How do males and females differ?

A
  • 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
30
Q

What do males bellow for?

A

deep and loud, signal to females to know where the males are

-also tells other males where they are

31
Q

Why do many males fall off the tree?

A

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

32
Q

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

A
  • fur length or thickness
  • colour
  • body size
  • shape
33
Q

What is Bergmann’s rule?

A

-medium to large sized mammals with large distribution usually exhibit larger body size in colder areas

(shorter ears, to conserve heat)

34
Q

What is the morphological cline in koalas?

A
  • 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
35
Q

What are the problems koalas face?

A
  • 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
36
Q

Why are some koala populations declining?

A
  • 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

37
Q

Why are some koala populations increasing?

A
  • high fertility, rapid population growth

- occur in habitat isolates (like reserves etc,.)

38
Q

What are the management techniques for overpopulated koalas?

A
  • 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
39
Q

What type of digestion do koalas have?

A
  • -hindgut fermenters, have gut 6-7 long

- long gut passage time= as need time to digest

BSC Zoology - Australian Wildlife (21 decks)

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