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The rufous bristlebird (Dasyornis broadbenti) is a ground-dwelling songbird - VCE - SSCE Biology - Question 5 - 2017 - Paper 1
Question 5
The rufous bristlebird (Dasyornis broadbenti) is a ground-dwelling songbird. The rufous bristlebird is found in gardens near thick, natural vegetation and builds nes... show full transcript
Worked Solution & Example Answer:The rufous bristlebird (Dasyornis broadbenti) is a ground-dwelling songbird - VCE - SSCE Biology - Question 5 - 2017 - Paper 1
Step 1
Define the term 'gene flow' and explain whether gene flow is likely to occur between these two populations.
Answer
Gene flow refers to the movement of alleles between populations due to interbreeding. It is important for maintaining genetic diversity within populations. Given the significant geographical distance of over 200 km between Population A and Population B, it is unlikely that gene flow will occur. The rufous bristlebird is also a weak flyer, and such an inability to travel long distances further isolates these populations. Therefore, genetic exchanges between these two populations are improbable.
Step 2
Both of the rufous bristlebird populations in Victoria are small. Referring to the theory of natural selection, explain why the rufous bristlebird is at risk of extinction.
Answer
Small populations like those of the rufous bristlebird may face several risks that contribute to their vulnerability. Firstly, reduced genetic variation can limit the pool of traits available for natural selection to act upon. If an environmental change occurs, the likelihood of having a favorable characteristic to survive diminishes. Moreover, with limited genetic variation, individuals can become more susceptible to genetic diseases. Secondly, due to their small size, there is a higher chance of inbreeding, which can increase the prevalence of harmful genetic traits. As the bristlebird is ground-dwelling, factors such as habitat destruction or introduction of predators can further jeopardize their survival, directly contributing to their risk of extinction.