Which statement best describes the effects of habitat fragmentation?

• A. It increases biodiversity due to more edge habitat.
• B. It reduces the number of invasive species.
• C. It fragments habitats but has no impact on biodiversity.
• D. It decreases biodiversity and can increase vulnerability to invasive species.

Answer: (D)

The main idea here is how breaking up a large habitat into smaller, isolated patches changes how many species can persist and how vulnerable the community is to invasives. When habitat is fragmented, total area shrinks, patches become smaller and more isolated, and edge effects—where conditions differ from the interior—become more pronounced. Smaller, isolated populations are more prone to local extinction because random events can wipe them out, and reduced gene flow lowers genetic diversity and adaptability. Edges often favor species that tolerate disturbed conditions, including many invasive species, which can spread more easily into fragmented landscapes and further disrupt native communities. So, biodiversity tends to decline and invasiveness tends to rise with fragmentation, making the statement about decreased biodiversity and increased vulnerability to invasive species the best fit. While some edge-adapted species may seem more common, the overall pattern is a loss of species richness and greater risk from invasives.