Mammalian Biogeography Ahd Phylogenetics

Question 1

What is the biggest order of mammals?

Answer 1

Rodentia

Question 2

What 2 phenomena have affected mammal distributions in the world?

Answer 2

1. Vicariance - continental drift, animals have no choice about where they’ve ended up, due to way land masses move: eg. Monotremes isolated in Australia and New Guinea
2. Dispersal movements - ability of animals to move eg. Marsupials
   - Laurasia: eutherians only
   - South America: marsupials and eutherians
   - Australia: marsupials

Question 3

What is the historical biogeography of marsupials

Answer 3

• 100mya origin in N America
• 65mya half mammal species in N America were marsupials
• 55mya present in Australia and S America
• were in Eurasia until 20mya

Question 4

What happened 2.5mya to the America’s?

Answer 4

‘great American interchange’

Dispersal of marsupials and placentals to/from north and south

Question 5

What do they think led to extinction of some marsupial species (Pleistocene extinctions)

Answer 5

NOT outcompeted by incoming species, they think by overkill

Question 6

Give an example of classes changing when phylogenetic trees take into account DNA instead of morphology?

Answer 6

Elephants and Sirenia (manatee and dugong) closely related