In vertical inheritance, parents pass genes to their offspring, but in horizontal transfer (HT), one species, often bacteria, passes genetic material to an unrelated species. In a 2022 study, herpetologist Atsushi Kurabayashi and his team investigated HT in multicellular organisms—namely, snakes and frogs in Madagascar. The team detected BovB—a gene transmitted vertically in snakes—in many frog species. The apparent direction of gene transfer seems counterintuitive because frogs usually don’t survive encounters with snakes and so wouldn’t be able to transmit the newly acquired gene to offspring, but the team concluded that BovB is indeed transmitted from snakes to frogs, either directly or indirectly, via HT.
Which finding, if true, would most directly support the team’s conclusion?
Correct answer: B
Explanation
Choice B is the best answer. If there are parasites that feed on both snakes and frogs, they could carry BovB from snakes to frogs. HT could occur “indirectly” through those encounters, which frogs are more likely to survive than snake encounters.
Choice A is incorrect. The team’s conclusion specifically argues that BovB is transmitted from snakes to frogs via HT, and this choice doesn’t mention snakes. Choice C is incorrect. The team argues that BovB is transmitted from snakes to frogs via HT, and this answer choice discusses a scenario in which the gene is not transmitted. Choice D is incorrect. Whether or not frog species with BovB are advantaged isn’t relevant to the team’s conclusion about how the gene is transmitted.
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