Lecture 23- Diversity of Australian mammals

Question 1

What are the mammalian characteristics?

Answer 1

• Have hair
• Females lactate (produce milk) to feed young
• Distinctive skeletal characteristics e.g. of jaw bones
• Endothermic

Question 2

What are the three groups of mammals?

Answer 2

1. Eutherians
2. Monotremes
3. Marsupials
   - Australia is the only continent with all three groups of mammals
   - No very large extant native land mammals in Australia

Question 3

What are the terrestrial Eutherians in Australia like?

Answer 3

• Rodents: rats & mice (64 spp.) * Bats (68 spp.)
• micro-bats (insectivorous)
• fruit bats
• Dingo (pre-European, present
  7-10,000 years)
• All relatively recent arrivals

Question 4

What is special about Rodents?

Answer 4

-extremely diverse

Question 5

What are the subgroups of Marine mammals?

Answer 5

-all Eutherians
• Whales & dolphins (Cetacea)
• Seals (Carnivora) • Dugongs (Sirenia)

Question 6

What species are in the Monotremes?

Answer 6

• Platypus
• Echidnas (2 species)
• only in Australia

Question 7

What is unusual in Monotremes?

Answer 7

• They have hair • They lactate (produce milk)
but…..
-are different to other mammals – have unique characters – some “reptilian”:
• Lay eggs • No teats (but feed
young on milk)
• Pectoral girdle and limbs reptile-like
-also have electroreception (to locate prey)
• Specialised sensors in bill • Detect very weak electrical fields

Question 8

Where are the young in Marsupials?

Answer 8

Females carry young in a pouch

Question 9

Where are Marsupials today?

Answer 9

• Australia, North America and South America

- Oldest fossils in N America ~ 115 MYA Oldest fossils in Australia: ~ 55 MYA

Question 10

What are the two main groups of Marsupials?

Answer 10

• Polyprotodont (more than one pair incisors) * Diprotodont (one pair incisors)

Question 11

What are the polyprotodont marsupials?

Answer 11

Carnivores or omnivores (Australia, PNG & South America) * Bandicoots & bilbies

• Marsupial carnivores (dasyurids)
• e.g. Bilby: endangered but being reintroduced into parts of its former range
• e.g. Eastern barred bandicoot, Tasmanian devil, Planigale, Phascogale, Quoll, Antechinus

Question 12

What are the diprotodont marsupials?

Answer 12

(herbivores or omnivores) Wombats, koala, kangaroos, possums etc

Question 13

What is the diversity of macropods (kangaroos) and possums and gliders?

Answer 13

-huge

Question 14

What are the marsupial moles?

Answer 14

diprotodont/polyprotodont?? sandy deserts, arid central & western Australia

Question 15

What was the Australian marsupial megafauna?

Answer 15

(Pleistocene; 2.6 MYA – 10, 000 YA)

• Diprotodon Palorchestes Thylacoleo
• • giant lizards, snakes & birds

Question 16

When did the magafaunal extinction occur?

Answer 16

• 50,000- 20,000 y.a. (Late Pleistocene)
• Several hypotheses:
• Climate change = increasing aridity
• Habitat change by humans (fire)
• Over-hunting by humans

Question 17

What did Professor Chris Johnson say about megafaunal extinction?

Answer 17

• Abrupt collapse following human arrival • No role for climate change • Removed species most demographically susceptible
to over-harvest • Not consistently linked to increased fire
= over-hunting by people

Question 18

What are the recent mammalian extinctions in Australia?

Answer 18

-Australia has an amazing diversity of mammals
-BUT
We have a very poor record of conserving terrestrial sp. post European settlement
- 23 species already extinct - many endangered (Crescent nailtail wallaby, Thylacine)
-higher than other regions
-mammals make up the biggest proportion of extinctions in australia with rodents being the most at risk
-Catastrophic decline of widespread species like the bandicoot, contraction of habitat

Question 19

What are the causes of extinctions?

Answer 19

• introduced mammals are serious pests
  • Ecosystem degradation • Competition with native species • Predators on native species
  -• Cat & fox (+ dingo??) • Horse & donkey • Buffalo, pig, goat, deer & camel • European rats & house mouse • Rabbit & hare

Question 20

What maybe a role for Dingos?

Answer 20

a role in conservation?
• Persistence of smaller marsupials that have geographic overlap with dingos
• Dingosmaycontrolfoxesand cats ? (especially in more arid areas

Question 21

What is Australian mammal assemblage special in?

Answer 21

• The only native terrestrial eutherians are rodents & bats
• Typical assortment of marine mammals present
• Monotremes * Australianmarsupials-
  very diverse & also different from American marsupials
• -ve impacts of introduced mammals