lecture 7 - mammals of fraser island

Question 1

what animals came to australia in the Early jurassic?

Answer 1

> ~200mya

> monotreme ancestors diverged early in ‘gondwana’ and spread throughout the southern globe, probably

Question 2

what animals came to australia in the early cretaceous?

Answer 2

> ~120mya
placentals probably split form metatherian ancestors in asia
placentals also dispersed but few reached australia at this time
because of land ridges

Question 3

what happened in late cretaceous?

Answer 3

> ~105mya

> passage to australia was getting more difficult because it was separated from gondwana by water

Question 4

what happened in the K/T event

Answer 4

> wiped out the dinosaurs and many other things.
opened to way for remaining mammals to diversify
in gondwana, the S.American mixture evolved in isolation
in Australia, the marsupials radiated
new cicumpolar currents started to freeze antartica

Question 5

how did the mass extinction event allow for the radiation of marsupials?

Answer 5

> wiped out a lot of animals - thus creating empty niches

> these niches were then filled by the marsupials

Question 6

what happened by the oligocene?

Answer 6

> ~35mya

> australia was on its way to warmer and drier climates, shaping the organisms that live here

Question 7

what are prototherians/monotremes?

Answer 7

> neonates hatch from an egg laid in pouch

earliest strain

Question 8

what are metatherians/marsupials?

Answer 8

> neonates born early and develop in pouch attached to teat

Question 9

what are eutherians/placentals?

Answer 9

> neonates born after development supported through a chorioallentoic placenta

Question 10

what sub-class and order is the short-beaked echidna in?

Answer 10

> subclass Prototheria
> order Monotremata

Question 11

what subclass and order is the yellow footed antechinus in?

Answer 11

> Marsupialia
> Dasyuromorphia
 - hop
 - rat/mice sized
 - insectivourous

Question 12

what subclass and order is the common dunnart in?

Answer 12

> marsupialia
dasyuromorphia
- teeth are pointy for piercing prey

Question 13

what subclass and order are long-nosed bandicoots in?

Answer 13

> marsupialia
Peramelemorphia
- pointy front teeth, then molars for grinding

Question 14

what order and subclass are northern brown bandicoots in?

Answer 14

> marsupialia

> peramelemorphia

Question 15

what is the subclass and order of the short-eared brushail?

Answer 15

> marsupialia

> Diprotodontia

Question 16

what subclass and order are swamp wallabies in?

Answer 16

> marsupialia

>diprotodontia

Question 17

what happened in the pleistocene?

Answer 17

> ~50,000mya
the australian plate collided with the asian plate forming an opportunity for new mammals to add to the fauna
HOWEVER, there is trace evidence of placentals already being here as early as the Eocene (50mya), before the final split from gondwana
there are a few teeth and jaw fragments from murgon controversially assigned to a placental, plus a fossil bat
presumably these managed to disperse here from the south, but they didn’t persist

Question 18

during which era did multiple waves of invasions ocur

Answer 18

> pliocene

Question 19

what different organisms are in the sub-class Eutheria ad Order - Rodentia

Answer 19

> a mosaic tailed rat whose ancestor arrived after the first ‘old endemics’ and before the ‘new endemics’
fawn-footed melomys
bush rat
have typical rodent dentition

Question 20

what is in the subclass -eutheria and order Chiroptera

Answer 20

> gould’s wattled bat

> a micro-chiropteran’ that uses echolocation

Question 21

when were all the new endemics present before?

Answer 21

> 1760

Question 22

what sub class and order are black rats in?

Answer 22

> eutheria

> rodentia

Question 23

how do you make abundance estimates?

Answer 23

> mark and recapture
if you know what proportion of the population you catch, then you know the size of the population, sort of.
trap initially and mark all the animals you catch.
trap again and see what proportion are marked
assume all your marked animals mix into the population in the meantime
all animals, marked and unmarked are equally likely to be caught
and the population size has not changed
of your recaptured animals, the proportion of marked animals in the second event gives an estimate of the proportion you catch in any event
apply this to the first event to get the original population size

Question 24

what is an example of the mark and recapture technique?

Answer 24

> suppose you trap 30 animals the first time round. you mark and release them.
suppose you then trap 25 animals, 5 of which are marked
based on a single estimate so far, your traps successfully retraped 5 in 25, or 1 in 5 animals
so you assume that your first trapping event successfully trapped 1 in 5 animals, i.e., there were 150 (5x30) animals out there

Question 25

what are some assumptions of the mark and recapture technique?

Answer 25

> animals are equally likely to be trapped each time

• not always the case
• trap happy or trap shy animals

Question 26

how can you improve the precision of mark and recapture?

Answer 26

> increase the number of samples taken
often its possible to treat multiple trapping events as serial estimates, leading to greater precision
in any case, its better if you trap heaps of animals, not just a few