Reports from individual black-footed ferret breeding programs sometimes suggest that allowing animals to choose among pedigree-screened mates preserves nearly as much genetic diversity as pedigree-based assignment while yielding more successful pairings. Such reports are not conclusive, however, because a program that begins with an unusually diverse population might obtain those results under almost any mating protocol. A multi-facility analysis accounted for each program’s starting diversity and found that mate choice retained nearly as much genetic diversity overall as assigned mating did. In the subgroup of programs that began with the least diversity, however, assigned mating retained substantially more diversity. ______ the analysis weakens the broad claim that mate choice is generally a costly compromise, but it also identifies conditions under which mate choice can carry a substantial genetic cost.
Which choice completes the text with the most logical transition?
When a transition introduces a sentence containing two claims joined by “but,” determine whether each claim follows from a different part of the preceding evidence. Choose a transition whose scope covers all the evidence needed for the entire sentence, not merely the clause that is easiest to notice.
Hints
Distinguish the findings
Identify what the analysis found across all programs and what it found specifically in the subgroup that began with the least diversity.
Track the two clauses
Determine which finding supports the clause before “but” and which finding supports the clause after it. Then look for a transition whose scope fits the entire sentence.
Step-by-step Explanation
Separate the two findings
The analysis produces a favorable overall result for mate choice: across the programs, it retains nearly as much genetic diversity as assigned mating. It also produces a less favorable subgroup result: among programs beginning with the least diversity, assigned mating retains substantially more diversity.
Map each finding to the final sentence
The first clause of the final sentence follows from the overall result because that result challenges the idea that mate choice is generally a costly compromise. The second clause follows from the subgroup result because that result identifies a condition under which mate choice can have a substantial genetic cost.
Choose the transition with the correct scope
Because the final sentence interprets both findings together, the transition must frame the analysis in its entirety. “Taken as a whole,” provides that scope without suggesting that the conclusion rests on only one result or conflicts with the evidence.