QUESTION 9 (3 marks)
Fossil evidence seems to show that the morphology of the Queensland lung fish has remained relatively unchanged for the past 100 million years. Describe the features of the theory of natural selection to explain how this may have occurred.
QCAA guide · typeset solution
QCAA sample response and mark allocation
9 | In a population, some individuals will have inherited traits that help them survive and reproduce. Because the helpful traits are heritable, and because organisms with these traits leave more offspring, the population will become adapted to its environment. In the case of the lung fish, if the environment remains relatively unchanged (i.e. no new predators or competitors, still a water-dwelling organism), there is no environmental selection pressure to select for any new mutations in morphology, so there is minimal change in the species. | • describes natural selection in terms of natural variation in a population includes traits that may be positive for survival in a given environment [1 mark] states that these traits survive in the population if there is a selection pressure [1 mark] • with reference to the lung fish states that the environment must have been relatively unchanged as no new morphological traits have been selected [1 mark] |
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