A lichen consists of a fungus living in symbiosis (i.e., a mutually beneficial relationship) with an alga. Although most branches of the complex evolutionary family tree of fungi have been well established, the evolutionary origins of lichen-forming fungi have been a mystery. But a new DNA study has revealed the relationship of This accounts for the visible similarity of certain lichens to more recognizable fungi such as mushrooms.
In general, fungi present complications for the researcher. Fungi are usually parasitic or symbiotic, and researchers are often unsure whether they are examining fungal DNA or that of the associated organism. But lichen-forming fungi are especially difficult to study. They have few distinguishing characteristics of shape or structure, and they are unusually analyzed, they will be found to belong to still more branches of the fungus family tree.
One implication of the new research is that it provides evidence to help overturn the long-standing evolutionary assumption that parasitic interactions inevitably evolve over time to a greater benignity and eventually to symbiosis so that the parasites will not destroy their hosts. The addition of lichen-forming fungi to positions along branches of that fungi can evolve toward mutualism and then just as easily turn back again toward parasitism.
What this question is testing
Your task
Capture the passage's overall primary point — the claim everything else supports.
Common trap
Answers that are true but too narrow (a single paragraph) or too broad (beyond the passage's scope).
Winning move
Summarize the whole passage in one sentence first, then match it to a choice.
Reading along? Open the full official question in LawHub — we show a fragment here and keep the reasoning in our own words.