question: What is Darwin 's belief about the accumulation of adaptive variations ?
answer: the accumulation of adaptive variations provides a scientifically testable mechanism for evolutionary speciation .
turker_answer: Darwin 's belief about the accumulation of adaptive variations is they provide a scientifically testable mechanism for evolutionary speciation .
rule-based: Darwin 's belief about the accumulation of adaptive variations is the accumulation of adaptive variations provides a scientifically testable mechanism for evolutionary speciation .