Evolution of Australian Biota

mechanisms found for seed dispersal

Pollination is the movement of pollen from the male part of a flower to the female part, Flowers can self-pollinate, Pollinators can include: possums, birds, insects and wind

theory of continental drift

first proposed in 1912 by Alfred Wedener. He theorised that all continents had previously been attached as a single landmass and continents drifted apart from each other.

meiosis

- Cell division - produces haploid 4 cells with half the number of chromosomes compared to the parent cell (haploid) - Used to make gametes for sexual reproduction - Gametes fuse together during fertilisation to form a zygote (when 2 gametes join, the normal no. of chroosomes is achieved) - occurs in sexual organs - genetically different - crossing over occurs

Procoptodon goliah is similar to

Kangaroo

mitosis

- Cell division - two diploid cells - identical - cells produced are called somatic cells - Division occurs only once - The stages are Interphase, Prophase, Metaphase, Anaphase and Telophase - occurs in body cells

the need to maintain biodiversity

- Essential for maintaining the natural functions of the Earth, such as providing clean water, air, productive soil, and recycling matter - Many human activities rely on biodiversity: agriculture, forestry, fisheries, etc. - The general health of the planet depends on biodiversity

biological evidence of gondwana

- Glossopteris and Gangamopteris are fossil plants found in rocks of the same age in Africa, Australia, India, South America, Antarctica and New Zealand (SAMAAANI without M). - possum as only marsupial found present on all the continents that made up Gondwana. - Flightless birds - Many present day species like Nothofagus rainforests found in Australia and NZ are considered relicts of Gondwanan rainforests. - Many groups of animals have close relatives in South America, Africa and India, including parrots and scorpions, which provides evidence that Gondwana was once joined.

the Huxley- Wilberforce debate on Darwin's theory of evolution

- Most people living in Europe in the 19th century believed that God created everything and humans did not evolve. There was a strong religious belief surrounding ideas about the creation of mankind, and people were shocked to see that someone had suggested that humans had evolved from animals. - Huxley supported Darwin's theory of natural selection - Wilberforce supported the theory that there was nothing in the theory of evolution. - Darwin's book The Origin of Species caused great uproar in the community, especially among religious clergy - Several debates happened, each side arguing they point of view of evolution - Wilberforce asked Huxley whether it was his grandmother or his grandfather that came from a monkey. - Huxley replied that he would rather have an ape for an ancestor than a person who uses their intelligence to "introduce ridicule into a grave scientific discussion"

the importance of the study of past environments in predicting the impact of human activity in present environments

- The knowledge gained from palaeontology (fossils) and the study of past environments can help us to understand present day ecosystems - This knowledge can be used to predict and determine the future for Australia's plants and animals - Palaeobiologists gain knowledge about the long term changes that have occurred in ecosystems over millions of years. At Riversleigh, fossils are being used to see how Australia's biota evolved

changing ideas of scientists in the last 200 years about individual species such as the platypus as new information and technologies became available

- The platypus was first described in the 1790s by scientists, although many people considered it as 'fake' as the platypus didn't fit current ideas of mammal nor reptile. - early 1800s, scientists observed platypus which was quite unreliable data. - currently and in the past 50 years, technology enabled scientists to study chromosomes using advanced microscopes and genetic fingerprinting, and thus in 1980s found that platypus' chromosomes resemble those of reptiles (they have both large chromosomes and micro-chromosomes), suggesting the platypus did not just belong to 'mammal'. - In the 2000s, radiotelemetry (implanting transmitters to track and record body temperatures of platypus). Scientists track temperatures for over a year, allowing them to understand how the platypus' body works. These discoveries in technology has resulted in changing ideas and the current conclusions. Features that separate it from other mammals: It lays eggs, no true teeth, and an absence of mammary glands, It has been shown to be able to regulate body temperature in a primitive way, It is a highly specialised animal

internal fertilisation

- occurs inside the female - used by most land dwelling organisms - organisms produce fewer sex cells changes of successful fertilization are much higher e.g. human, horse

evidence suggesting that crustal plates move over time

- the age of the sea floor around mid-ocean ridges - the matching edges of continents - fossils of similar organisms found in different parts of the world

daughter cells produced mitosis

2

what is gondwana

225 million years ago all continents were joined in a 'supercontinent' called Pangea. In the Jurassic, 160 million years ago, Pangea split into two super continents with Gondwana in the south - included Antarctica, South America, Africa, India, NZ, Madagascar and Australia

daughter cells produced meiosis

4

describe evidence of changing environments in Australia over millions of years

65 million - Australia and Antarctica joined, part of Gondwana, cool and wet, Fossils of club mosses which grew in swamps have been found in Narrabeen providing evidence that Australia was covered by shallow water. 40 million: Australia and Antarctica separate, cool and dry, fossils of aquatic organisms such as crocodiles have been found in areas that are inland and dry in present-day times, suggesting the presence of lakes in the interior in the past. 30 million: Australia drifting north, warmer 7million-present: Australia drifting north, warmer and drier, plants of Australia's present-day open forest, woodland, grassland and scleophyll forest show adaptations to dry, harsh climatic conditions. No fossil remains of these plants (e.g. waratahs) have yet been discovered, implying that they are recent vegetation and were not part of the Australian vegetation millions of years ago.

timeline of changes of australia

7 - 0: Australia was still part of the super continent Pangaea. During this time, it changed from being covered in sea to being mostly above sea level. It moved increasingly further south during this time and experiences Earth movements and volcanic activity in the Devonian period. River and lake systems formed during the Triassic Period. Dinosaurs and other reptiles appeared, followed by Australian mammals and birds. Ferns and the first flowering plants were abundant 30 - 7: Pangaea split into Gondwana and Laurasia. Australia experiences activity that is more volcanic. Dinosaurs became extinct, grasses appeared and rainforests of beech trees developed. Flowering plants became more abundant. 45 - 30: Australia was still connected to Antarctica, but was separating from New Zealand. During this time sea levels rose and Australia was partially covered in sea again. Initially all organisms were marine during this period, but eventually the first land plants (club mosses and lichens) emerged, then seed ferns (Glossopteris), and eventually conifers. Jawless fish were followed by fish with jaws. 65 - 45: Australia and Antarctica began to separate, with Australia moving northwards. Australia also separated from the rest of Gondwana. Acacias and grasses such as Spinifex predominated as the climate became drier. Sclerophyll forests have become more fire-tolerant. 160 - 65: Australia became drier as it moved The separation of Australia from Antarctica was complete. The area occupied by rainforest steadily decreased and was replaced by grassland and sclerophyll forests. 500 - 160: Australia became drier as it moved north and an ice cap formed over Antarctica. Temperate rainforests predominated.

relationship between variation within a species and the chances of survival of species when environmental change occurs

According to theory of natural selection, there will always be variations within species. When environmental change occurs, the individuals that has a variation that allows them to live in the new environment can survive, while those without the variation die out. So, the greater the variation within a species, the greater the chance that it will be able to survive in a situation of environmental change.

changes in the distribution of Australian species, as rainforests contracted and sclerophyll communities and grasslands spread, as indicated by fossil evidence

As Australia became warmer and drier, rainforests shrank, and grasslands and sclerophyll communities increased. As a result, those organisms well suited to these conditions undertook "adaptive radiation‟. Two groups that are part of the sclerophyll family are eucalypts and acacias. Both forms have adapted to survive in dry hot conditions. The 950 species of acacia are found almost everywhere, from tropical to temperate, arid and semi-arid. The 800 species of eucalypts are found mainly in open woodland and forests. Marsupials, as it got warmer, in Australia diversified to many ecosystems. Placentals died out, except bats. Frogs in Australia have developed an independence from permanent water, and many of them now occupy inland arid areas.

where asexual reproduction is advantageous + e.g.

Asexual reproduction results in the offspring being genetically identical to the parent. If the environment is unchanging, and the characteristics of a particular organism are well suited to the environment, then asexual reproduction would be advantageous, since all the offspring will have the advantageous characteristics. e.g. eucalyptus saligna

similarities between mitosis and meiosis

Both are types of cell division. Chromosomes are replicated before both types of divisions

reasons for the extinction of megafauna

Climate Change: Megafauna mainly suited to glacial conditions. Their large bodies enabled them to live in extreme conditions, therefore with a change of climate. In Australia, the temperature changed from cold-dry to warm-dry. As a result, water sources began to dry up, and many animals lost their habitat and died out. Human Expansion: time of extinction of megafauna matches very closely the pattern of human migration into these areas. Megafauna are also large and slow, which makes them susceptible to hunting. In Africa, humans' evolution occurred there, so hunting increased slowly, allowing animals to adjust. That is why there are still megafauna there. However, in places where humans arrived as skilled hunters, the most extinction occurred. - Living fossil (or relict species) are organisms that have changed little or not at all since ancient times.

current theories that provide a model to account for these changes in Australian fauna and flora

Climate Change: One theory surrounding the extinction of Australian megafauna is climate change. It can be argued that climate change might have driven vegetation change, periodic drought, and increased seasonality. It is said that animals were not able to adapt fast enough to this change and slowly became extinct. Increase in climate and decline in water availability is shown in the contraction of rainforests and in the expansion of open woodland. The rise and fall of Australian mammals and the radiation of marsupials is also related to climate Human Impact: Humans arrived as an exotic species in Australia. Their actions may have contributed to the megafauna's extinction and use of fire changed the environment. Arrival of Europeans drastically changed the environment, due to unsustainable agricultural methods.

Darwin's observations of Australian flora and fauna and relate these to his theory of evolution'

Darwin's theory of evolution explains the evolution of Australian biota. In any population, there are variations. The individuals that survive and reproduce are well adapted to the environment; they have favourable conditions (survival of the fittest). Favourable conditions are passed on to offspring; they become more and more common in the population. When Darwin travelled to Australia, he observed that many Australian flora and fauna had similar counterparts from other parts of the world. Darwin Observed: Crows in Australia look like English Jackdaws, another bird looked like an English magpie, the rat-kangaroo (potoroo) was similar to a European rabbit and the Australian ant-lion was almost identical to its European counterpart. Australian flora was well adapted to Australian conditions, suggesting that natural selection had favoured them. The great amount of marsupials in Australia, which Darwin considered inferior to placentals, showed that they only existed since there was no competition. No competition meant no natural selection and so marsupials thrived.

describe some Australian fossils, where these fossils were found and use available evidence to explain how they contribute to the development of understanding about the evolution of species in Australia

Naracoorte (South-east South Australia): Giant short-faced kangaroo showed how megafauna used to live in that area and have now evolved into kangaroos (with grey kangaroos living in that area)

a current effort to monitor biodiversity

Tasmanian Devil captive breeding programs this marsupial facing extinction is being decimated by a contagious cancer called devil facial tumour disease, which is passed from devil to devil when they bite each other. This program holds and breeds devils free from the disease in zoos and fauna parks — both in Tasmania and on the mainland — with the long-term goal of returning disease-free devils back into Tasmania. Another important aspect of the captive insurance program is to minimise adaptation to captivity and to retain wild behaviours.

mechanisms found for pollination

birds - attracted by large and colourful petals, rarely fragrant because birds ahve little smell, large amount of nectar produced, anthers often colourful, stigma so not enclosed by petals insects - large and colourful, insectes attracte to scent, nectar at base of petals so insect must enter to reach nectar, stigma enclosed within flower which is sticky, pollen grains are sticky and small amount produced wind - petals inconspicuous, small and dull in colour, no scent, anthers pritrude outside flower so easily blown by wind, incrased SA of long stigma to trap wind boren pollen, many small and light pollen grains

mechanisms to ensure Animal Survival of Embryo - platypus, kangaroo, gastric-brooding frog

montreme - Platypus Embryo - develops inside the egg within the uterus for 4 weeks, external incubation for 10 days (shell for protection in external environment). Eggs are stuck to the fur of abdomen. eggs layed in burrow for protection and remains in burrow for several months for development marsupial - Kangaroo Internal fertilisation - Partial internal development with very short gestation period in the uterus, pouch to protect young amphibians - gastric-brooding frog external fertiisation and internal development by swallowing and stops stomach movements by not eating

mid-ocean ridges

occur where continental plates are moving apart. Spreading zones are the new areas of floor created at ridges where molten rock rises out from the mantle and solidifies. There are spreading zones on the southern side of the Indo-Australian plate, and collision zones on the northern side, implying that Australia is moving north.

mechanisms to ensure Survival of Young after Birth

platypus - After platypus hatching, young platypus remains in the burrow for several months, obtaining nutrients by suckling on mums mammary glands. Young leave nest when they have grown fur kangaroo - After birth, underdeveloped, young crawls into mother's pouch and continues development while feeding on milk for 4 months.

geological evidence of gondwana

spreading zones: areas of new ocean floor forming between continental places, evidence to support the theory of Gondwana as it suggests that the ocean floor is constantly expanding. mid-ocean ridges: when two plates are moving apart, and magma wells up, spreading across the floor, they suggest that the rock that forms the ocean floor is increasingly older the further away it is from the ridge, suggesting the plates have been moving for a long time. Continents matching: between Aus. and Antarctica, Africa and South America fit, suggesting they were once joined

how the evolution of these reproductive adaptations has increased the chances of continuity of the species in the Australian environment

these adaptations have developed as a result of natural selection, and the species are the fittest for their environment. Since these reproductive adaptations are well suited to their environment, chances if continuity is increased for the plant.

examples of variation between members of species

white-naped honeyeater: In Australia, eastern populations have a short bill and an orange eye-patch. Populations in western Australia have larger bills and white or green eye-patches. The common heath: this flower shows remarkable variations in the colour of the flowers, from pure white, to pink, to deep red.

the success of internal and external fertilisation in relation to the colonisation of terrestrial and aquatic

• External fertilisation is successful in aquatic environments, as the gametes can spread very far and wide in the water, increasing the chances meeting other gametes from the opposite gender, encouraging fertilisation • External fertilisation would not succeed on land, as there is no water through which the male gametes can swim, and the gametes would not spread very far, as the buoyancy of water is not there to support their travelling. • Internal fertilisation enabled the colonisation of land, as the watery environment needed is provided by the female's physiology

mechanisms found for asexual reproduction

• No gametes are formed • Plants are clones of the parent plant. Good for rapid reproduction after a crisis • Lack of variation meaning that it is not good with a sudden environmental change • Example: runners that have nodes on which the new plant grows

external fertilisation

• Occurs outside the female - the male releases sperm cells onto the egg cells as the female lays them • Used by fish and most water dwelling animals (e.g. amphibians). • However, the chances of fertilization are very low, so huge numbers of eggs and sperm are needed to ensure enough offspring are produced • Used by fish because water is available for sperm to swim in E.g. Fish, frog

the ways in which palaeontology assists understanding of the factors that may determine distribution of flora and fauna in present and future environments

• Using what we know about past climates and the effect that the climates had on flora and fauna we can predict what will happen in the future. • Fossils show us what happened to Australia's plants and animals as the continent became hotter and drier. • As the greenhouse effect raises temperatures on Earth and as the ozone layer is depleted more and more, the Earth's climate and environments will change and therefore the distribution and abundance of species will also change. • Analysis of plant and animal fossils can allow palaeontologists to create a picture of the ecosystems at the time. Main causes of extinction: climate change and agricultural hunting The main findings of palaeontology in Australia are: 1. Loss of biodiversity over time - reduction in rainforest 2. Thylacine - numbers were already declining, Europeans finally killed them all