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Case study


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    • 2. DESCRIBE THE CHANGE THAT OCCURRED WITHIN SPECIESThe Red Kangaroo is the largest living Marsupial in the World• And are found throughout the arid regions of mainland Australia• Part of the macropod family à• The Macropod family is alleged to have evolved from either Phalangeridae (possums) or Burramyidae (pygmy-possums)• Due to the harsh environments they have evolved some breeding strategies • E.g à reproduction ceases during drought but begins within days of rain. They produce two different kinds of milk at the same time • Other studies have suggests hopping evolved even earlier in forested environments (30 million years ago)• Red kangaroos are the most recently evolved kangaroos (Dawson 1995)• “ The first preference of Red Kangaroos is green grass, followed by green forbs and mature grass. Grass can provide plentiful energy, but it is tough to digest. So structural and physiological adaptations have evolved to exploit this abundant food source
    • 3. os/ m/animals/mammals/gray- kangaroo/
    • 4. DESCRIBE THE CHANGE IN ENVIRONMENT THAT OCCURRED• Ranges throughout southern Australia because these are arid or semi-arid areasIncreased because:• Australia moved further north (45 mya) which changed the climate, became more arid• Aboriginals scavenged their predators such as dingos• European settlement (1788) - due to the clearing of land for their crops , development of grassland and introduction of livestock which provided additional food• National Parks and Wildlife Act 1972 – protect the conservation of kangaroos
    • 5. IDENTIFY WHETHER THE ENVIRONMENTAL CHANGE WAS A PHYSICAL CHANGE OR CHEMICAL CHANGEThe environmental change is considered a physical change during the arrival of Aboriginal and colonisation of Europeans.
    • 6. IDENTIFY AND DESCRIBE THE SELECTIVE PRESSURE ACTING ON ORGANISM AS A RESULT OF ENVIRONMENTAL CHANGEThe selective pressure in the environment is that the humans don’t hunt for them for food or leather hides.Another selective pressure is the change in Australian soil which is now more red (due to oxidation) and one of the organism’s characteristics is its red fur which camouflage with the send sands . This is supported by the theory of natural selection which states that organisms that is better adapted to the environment will survive and therefore produce more offspring.Therefore, red kangaroos are now more abundant.
    • 7. EXPLAIN HOW (4) LED TO (2)Agriculture has helped increase the habitat of the larger species of kangaroos as well as providing them more food. So as sheep farms increase, and available unsuitable (for sheep) forage increases, so does the population of Red Kangaroos. This is because the RedKangaroo is able to digest grasses that sheep do not eat.
    • 8. DISCUSS WHETHER YOU CONSIDER THE EXAMPLE TO BE A FORM OF MACRO-EVOLUTION OR MICRO-EVOLUTIONMacro-evolution• Definition: major evolutionary change over a long period of time• Therefore, red kangaroo may have undergone macro evolution: As it evolved from ancestors with different geneticmake up than it has now such as possums and wallabiesbut shares some DNA sequences which proves that thesedifferent species came from the same ancestors.