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 acidity increases due to climate change, purple sea urchins that possess traits conferring resistance to these acidic conditions will have a survival advantage. Over time, this selective pressure will likely lead to an increase in the frequency of these advantageous traits within the population.
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 if purple sea urchins have exoskeletons that are less resistant to acid, they are more likely to be negatively impacted by increasing ocean acidity. As a result, these individuals would have a lower chance of survival and reproduction, leading to a decrease in their prevalence 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 as it aligns with the concept of natural selection. Individuals with resistant exoskeletons will be better suited to survive in increasingly acidic waters, allowing them to thrive and reproduce, ultimately leading to a higher frequency of this 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 relevant to the question of acid resistance. There is no evidence presented that longer, more rigid spines provide any advantage in acidic conditions, and thus this trait is not directly related to the survival of purple sea urchins in the context of climate change.
D) Purple sea urchins with a trait of having shorter, more flexible spines would become more common.
Similar to option C, this choice does not address the issue of acid resistance. The flexibility or length of spines does not inherently confer an advantage in acidic environments, making this option irrelevant to the population's evolution in response to increasing ocean acidity.
Conclusion
The correct answer is B, as it accurately reflects the evolutionary response of purple sea urchins to increasing ocean acidity through natural selection. The other options fail to recognize the importance of acid resistance in survival under changing environmental conditions, focusing instead on traits that do not directly contribute to the individuals' ability to thrive in more acidic waters.