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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. Explain how natural selection can lead to differences in phenotypes between these two sea star species.
Answer
Natural selection affects the phenotypes of Cryptasterina species through differential survival and reproduction based on environmental pressures. Over time, individuals from the ancestral population that possessed advantageous traits for their specific environments—such as temperature tolerance or predation avoidance—would be more likely to survive and reproduce. For example, cryptasterids in warmer northern waters may develop faster growth rates and reproductive strategies suited for higher temperatures. Conversely, those in colder southern waters may exhibit traits that enhance survival against predators, such as better camouflage or slower maturation rates. As these traits become more common, noticeable differences in phenotypes will emerge, reflecting the adaptation of each species to its unique environmental conditions.
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
C. pentagona is expected to have the highest diversity of alleles due to its sexual reproduction mode. Sexual reproduction involves the combination of genetic material from two parents, leading to greater genetic variation among offspring. In contrast, C. hystera's self-fertilization restricts genetic diversity as it relies on a single individual's genetic material. This reduced diversity can limit adaptation to environmental changes and resilience against diseases. Therefore, C. pentagona, with its free-floating sperm and eggs, is likely to exhibit a broader range of alleles compared to C. hystera.