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Two species of Cryptasterina sea stars are found in coastal Queensland - VCE - SSCE Biology - Question 8 - 2016 - Paper 1
Question 8
Two species of Cryptasterina sea stars are found in coastal Queensland. Cryptasterina pentagona is found in warmer water further north, while Cryptasterina hystera i... show full transcript
Worked Solution & Example Answer:Two species of Cryptasterina sea stars are found in coastal Queensland - VCE - SSCE Biology - Question 8 - 2016 - Paper 1
Step 1
a. Using the information above, explain how natural selection can lead to differences in phenotypes between these two sea star species.
Answer
Natural selection leads to differences in phenotypes through the differential survival and reproduction of individuals possessing certain advantageous traits. The two species of Cryptasterina likely experienced varied selective pressures due to the difference in water temperatures and predation.
For instance, C. pentagona thrives in warmer waters, which may favor traits such as faster movement or resilience to higher temperatures. In contrast, C. hystera, found in cooler waters, may have developed traits that enhance survival under colder conditions. Over generations, these traits become more pronounced as individuals with advantageous phenotypes are more likely to survive and reproduce, ultimately leading to the divergence of these two species.
Step 2
b. Using this information about reproduction strategies, which species of Cryptasterina would you expect to have the highest diversity of alleles? Explain your answer.
Answer
Cryptasterina pentagona would be expected to have the highest diversity of alleles due to its method of external reproduction. Sexual reproduction allows for the mixing of genetic material from two different individuals, creating a wide variety of allele combinations in the offspring. In contrast, C. hystera's self-fertilization results in less genetic variation, as it relies on a single individual's genetic material. This limitation in genetic exchange typically leads to lower genetic diversity compared to species that employ sexual reproduction.