StrengthenDiff: Hardest
Logic Breakdown
Passage Summary: Salmon were put in a lake and split into two groups—one in deep water and one in shallow water. Now they are genetically different, and scientists think they changed to fit their new environments.
Conclusion: The two distinct salmon populations in Lake Clearwater have genetically adapted to their specific deep or shallow habitats.
Reasoning: Since being introduced in 1940, the salmon split into two groups that do not interbreed and now show genetic differences.
Analysis: To strengthen this hypothesis, we need to bridge the gap between 'they are different' and 'they adapted to their environment.' The best way to do this is to show that the specific genetic differences provide a survival advantage in their respective lake zones. If the deep-water salmon have traits that help them in the dark and the shallow-water salmon have traits for the light, the adaptation theory becomes much stronger. Look for an answer that connects the genetic traits to environmental utility.
Conclusion: The two distinct salmon populations in Lake Clearwater have genetically adapted to their specific deep or shallow habitats.
Reasoning: Since being introduced in 1940, the salmon split into two groups that do not interbreed and now show genetic differences.
Analysis: To strengthen this hypothesis, we need to bridge the gap between 'they are different' and 'they adapted to their environment.' The best way to do this is to show that the specific genetic differences provide a survival advantage in their respective lake zones. If the deep-water salmon have traits that help them in the dark and the shallow-water salmon have traits for the light, the adaptation theory becomes much stronger. Look for an answer that connects the genetic traits to environmental utility.
Passage Stimulus
Passage Redacted
Unlock Full Passage22.Which of the following, if true, most strongly supports the researchers' hypothesis?
Correct Answer
A
By showing there was no interbreeding with native salmon, A rules out a major alternative source of genetic differences (introgression). Given that the two sockeye groups occupy different habitats and now differ genetically, eliminating gene flow from natives makes it more likely that the divergence is due to adaptation to those distinct habitats.
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