62. Climate change is affecting the chemistry of the world's oceans. In particular, the ocean water is becoming more acidic. For purple sea urchins, this poses problems as their calcium-based exoskeletons may dissolve in acidic conditions. In a certain population of purple sea urchins, some individuals possess a trait that makes their exterior more resistant to acid. If global climate change continues (as predicted) to make ocean water more acidic, how might this population of purple sea urchins evolve in response to this increased acidification?
Answer: B
Purple sea urchins with a trait that make their exoskeletons resistant to dissolving in acidic water would become more common.
As ocean water becomes more acidic due to climate change, purple sea urchins with traits that enhance resistance to acid will have a survival advantage. This adaptation will likely lead to an increase in their population over time.
A) Purple sea urchins with a trait that make their exoskeletons less resistant to dissolving in acidic water would become more common.
This option is incorrect because as ocean acidity increases, sea urchins with less resistant traits are more likely to suffer from exoskeleton dissolution and thus would be less likely to survive and reproduce. Therefore, such traits would not become more common in the population.
B) Purple sea urchins with a trait that make their exoskeletons resistant to dissolving in acidic water would become more common.
This option is correct. Individuals with exoskeletons that can withstand acidic conditions will have a greater chance of survival and reproduction in increasingly acidic oceans, leading to a higher frequency of this advantageous trait in future generations.
C) Purple sea urchins with a trait of having longer, more rigid spines would become more common.
This option is not supported by the context of acidification. While longer spines may provide some benefit in terms of predator avoidance, they do not directly address the issue of exoskeleton resistance to acidity. The evolution of traits is primarily driven by environmental pressures related to the specific challenge posed by acidification.
D) Purple sea urchins with a trait of having shorter, more flexible spines would become more common.
This option is also incorrect as it does not relate to the primary concern of acid resistance. The flexibility or length of spines does not provide a direct advantage against the impacts of increased ocean acidity, and thus would not be favored in the context of this environmental change.
Conclusion
In summary, the evolving population of purple sea urchins will favor individuals with traits that enhance acid resistance, making option B the only viable response to the challenges posed by climate change. All other options fail to address the specific survival needs dictated by increasing ocean acidity, highlighting the importance of trait relevance to environmental pressures.