Identify and classify the major drivers of biodiversity loss (habitat loss/fragmentation, invasive species, pollution, overharvesting, climate change) using documented historical case studies.
Ecologists often organize the leading causes of biodiversity loss with the acronym HIPPCO: Habitat destruction, Invasive species, Population growth (human), Pollution, Climate change, and Overharvesting. Habitat destruction and fragmentation -- breaking one large habitat into smaller, disconnected patches through roads, farms, and development -- is generally considered the single largest driver worldwide, because fragmentation adds harmful "edge effects" (more exposure to wind, predators, and invasive species at a patch's border) and isolates populations from each other, reducing their genetic exchange.
Two real, thoroughly documented American cases illustrate the other categories starkly. Overharvesting: the passenger pigeon numbered an estimated three to five billion birds in the early 1800s, the most numerous bird in North America, yet unregulated commercial hunting drove it extinct by 1914 -- a stunning collapse that helped motivate the country's first wildlife protection laws, including the Lacey Act of 1900. Invasive species: zebra mussels, introduced to the Great Lakes in the late 1980s via ship ballast water, have since disrupted native mussel populations and food webs across the entire region -- a still-ongoing case.
Mastery looks like: They can classify a real or described case correctly under HIPPCO, explain edge effects and fragmentation in their own words, and recognize when more than one cause is acting on the same decline.
Common stumbles: Assuming every decline has exactly one cause; confusing "habitat loss" (less total habitat) with "fragmentation" (the same or similar total habitat broken into disconnected pieces).