Passage Summary: The 'bottom-up' theory claims that plants are the real bosses of the ecosystem, and what happens to predators at the top doesn't really trickle down to affect the plants or herbivores.

Conclusion: Reducing the number of predators in an ecosystem will have a negligible effect on the rest of that ecosystem.

Reasoning: Ecosystems are built from the bottom up, meaning plant availability dictates herbivore levels, which in turn dictates predator levels.

Analysis: To weaken this theory, we need to find evidence of a 'top-down' effect where predators actually do influence the lower levels of the food chain. The argument assumes a one-way street of influence starting from the plants. If we find a scenario where removing a predator causes the herbivore population to explode and subsequently wipe out the plant life, the 'bottom-up' theory is effectively undermined. Look for an answer that shows a change at the top of the food chain causing a significant ripple effect below.