What threatens biodiversity?
• Natural extinction: Species have being replaced in the earth history. Mass extinction happened by the end of Permian and the end of Cretaceous, caused by climate change to too hot and dry. The climate changes were believed to be triggered by large asteroids struck earth — Catastrophes. (Table 13.3) “Greenhouse effect” caused the global warming up could lead to the similar result. • Human-caused reduction in biodiversity: Species are disappearing at an increasing rate. • Habit destruction: Destroy forest for for farming or housing (Fig. 13.10). • Over hunting and fishing caused many species extinct (Figs. 13.9, 13.11, 13.12). • Commercial products and live specimens: of endangered species (Fig. 13.13) • Rare commercial products, e.g., ivory (Fig. 13.14) • Medicine, e.g., tiger bones, ginseng roots • Pets: birds, fish, mammal (Fig. 13.15) • Predator and pest control: (Fig. 13.16) • Exotic species introductions: bioinvaders: Kutzu vine, leafy spurge, purple loosetrife, zebra mussels, r
