Based on the logical progression of the passage below, what single word best completes the author's final sentence?
Answer:In ecological theory, the 'redundancy hypothesis' posits that ecosystems possessing high biodiversity contain multiple species performing overlapping ecological roles. Under this model, the local extinction of a single species has a negligible impact, as ecological equivalents seamlessly compensate for its absence, thereby conferring systemic resilience. Yet, recent field studies reveal that this apparent functional overlap relies heavily on benign environmental conditions. When an ecosystem faces severe, anomalous stress—such as a prolonged drought—these 'equivalent' species often display differing physiological tolerances and may simultaneously fail to perform their shared roles. Thus, while functional redundancy appears to guarantee ecological resilience in stable periods, relying on it to predict ecosystem survival under extreme duress may actually mask underlying 【vulnerability】.
Answer
vulnerability (or fragility, instability, weakness, susceptibility)
The author contrasts the 'resilience' seen during stable periods with the reality of 'extreme duress', where seemingly redundant species fail simultaneously. Therefore, assuming the ecosystem is safe actually hides its true susceptibility to collapse. Words like 'vulnerability', 'fragility', or 'instability' logically complete the contrast against 'resilience'.
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Logical Continuations in Reading Comprehension