Passage
Paragraph 1
For decades, plant biologists viewed forest ecosystems primarily through the lens of Darwinian competition, assuming trees fought individually for sunlight, water, and soil nutrients. This paradigm shifted dramatically with the discovery of mycorrhizal networks—underground webs of fungal mycelia that connect the roots of distant trees. Pioneering research demonstrated that these networks facilitate the transfer of carbon, nitrogen, and water between plants, prompting some ecologists to characterize forests as cooperative, quasi-altruistic superorganisms.
Paragraph 2
However, recent critical reviews suggest this cooperative model may be overstated. Skeptics argue that much of the evidence for active resource sharing is based on greenhouse experiments that fail to replicate complex forest dynamics. In natural settings, they contend, the net direction of resource transfer is difficult to track, and fungi may simply be trading resources to maximize their own fitness rather than acting as neutral conduits for plant mutualism.
Paragraph 3
Furthermore, evolutionary theorists emphasize that natural selection operates on individual organisms, not communities. From this perspective, the fungal network is an arena of exploitation: dominant trees may feed off the network at the expense of shaded seedlings, or fungi might manipulate host trees to extract additional sugars. Rather than a network of mutual aid, the mycorrhizal web is more accurately described as a complex negotiation, where cooperation exists only when the self-interests of the individual tree and the fungus happen to align.
Based on the passage, match each paragraph to the central argument it develops.
- Paragraph 1The discovery of underground connections challenged the traditional focus on competition, introducing a model of cooperative forest superorganisms.
- Paragraph 2Methodological limitations cast doubt on the cooperative forest model, suggesting resource exchange may actually serve fungal self-interest.
- Paragraph 3Evolutionary principles suggest that fungal networks are shaped by individual survival interests, resulting in exploitation and negotiation rather than pure altruism.