Ecologists have long debated how temperate tree species survived the Last Glacial Maximum in northern latitudes, traditionally pointing to vast southern refugia. However, recent fossil pollen analyses suggest the existence of northern microrefugia—isolated pockets of hospitable microclimates that sustained small populations. While some researchers remain skeptical, arguing that the low densities in these pockets would prevent long-term genetic viability, evolutionary geneticist Clara Vance demonstrated that high levels of localized gene flow could counteract genetic drift. Consequently, Vance's model suggests that northern microrefugia were not mere survival dead-ends but active evolutionary incubators.
Which choice best describes the overall structure of the text?
- It presents a traditional explanation for a biological phenomenon, introduces an alternative hypothesis, describes a challenge to this new hypothesis, and details research that resolves this challenge.Answer
- BIt describes a scientific debate, outlines the methodology used to resolve it, presents a primary finding, and then questions the validity of that finding.
- CIt introduces a recent scientific discovery, explains the mechanisms behind it, compares it to an older theory, and concludes that both theories are partially correct.
- DIt proposes a solution to an ecological problem, details the historical context of the problem, evaluates a criticism of the solution, and suggests areas for future research.