Lecture Eighteen - Evolution and biogeography of the Australian fauna II Flashcards
At what points in the splitting of the supercontinents did different species come into existance?
When South Ameria, Africa and Australia were joined:
Lung fish, burrowing frogs, long necked tortoises and ratite birds evolved.
When south America and Australia were joined:
Hylid frogs, horned turtles, parrots and marsupials evoled.
What is adaptive radiation?
The diversification of a group of organisms into forms filling different ecological niches.
What are homologous and analogous structures?
Analogous structures = performing a similar function but having a different evolutionary origin, such as the wings of insects and birds.
Homologous structure = similar in position, structure, and evolutionary origin but not necessarily in function.
When and why did South American marsupials go extinct?
Most South American marsupials went extinct in the late Miocene/early Pliocene.
They were likely outcompeted by placental mammals from North America (the Great American Interchange 3 mya).
Describe the adaptive radiation of marsupials in Australia.
Many forms evolved from common ancesters.
Ecological roles include insectivours, carnivours and herbivours.
Vary in body form from quadrupedal to bipedal.
All Australian marsupias are endemic.
No large marsupial carnivours.
What are the differences between marsupials and placentals?
Marsupials:
Short gestation and long lactation.
High metabolic scope.
Low basal metabolism.
Poorly developed behaviour patterns.
Placentals:
Long gestation period and short lactation.
Low metabolic scope.
High basal metabolism.
More highly developed behaviour patterns.
What are characteristics of animals which live in predictable and unpredictable environments?
Predictable environments - E.g. Marsupial mouse:
Females - large investment in young.
Males - die off over winter.
Supply of insects seasonally restricted.
Birth timed with insect abundance.
Unpredictable environments - E.g. Kangaroo:
Females - continue to produce young, but can pause development.
Young only develop if conditions are favourable.
Abandon young in bad conditions.
Reproduce quickly in good year.
Large size of adults.
What are some plant defences against herbivoury?
Chemicals:
Poisons - terpenes (volitile, flammable) and cyanides.
Digestibility reducers - tannins, bind with dietary proteins.
Physical properties:
Cell wall, fibre - tough.
Abrasives.
Timing:
Seasonal flowering and growth.
Patchy distribution of seeds, fruits and leaves.
Animals cannot specialise on a resourse unless it is always avaliable.
Plants may swamp predators by synchronised flowering or leaf production.
Describe the evoltion of the kangaroo group.
