Practice question

“Nile perch” for species introduced to lake victoria causing native fish decline. This relationship follows from the ecological mechanism represented by the terms in the item, not merely from an association between their names. Ecological interpretation requires separating the immediate process from its broader consequence. A mechanism operating through physiology or behavior can scale up to alter survival, reproduction, abundance, distribution, and community structure. The remaining alternatives—“Cane toad”, “Zebra mussel”, “Achatina fulica”—refer to different states, processes, or scales and therefore do not express the same causal relationship. The inference is strongest when the relevant variables, spatial boundary, and time scale are explicit. Context can alter the magnitude of an effect without changing the definition of the focal concept. Field observations could test this account by measuring the proposed driver and the demographic or ecosystem response while controlling plausible confounding factors. This distinction matters because similar surface patterns can arise through different mechanisms, whereas ecological prediction depends on identifying the mechanism that actually changes rates.