Ch.3: Where is the World’s Biodiversity? - The tropics and coral reefs harbor most biodiversity- Understanding hotspots & the causes of biodiversity will help us to manage the world’s biota- Most of the world’s biodiversity has yet to be described- More taxonomists are needed.-I. How many species?A. ~ 2 million namedB. Most species have NOTbeen named/describedWe have just begun to describe fungi, nematodes, insects, and bacteria. 20,000 new species described each year! Page 72, Figure 3.6Page 72, Figure 3.6; Primack 2002Most insects collected by “fogging” rain forest trees are new to scienceC. Current estimates: 10 million? 100 million species?D. Taxonomy at fastest pace ever, but too few workersMany species will go extinct before they can be described.II. Global patternsA. Most species rich:1. tropical rain forestsa. contain >50% of all speciesb. occupy 7% of land area5-30 million spp. of insects? >90% of the world’s species???c. 2/3 of world’s plant spp.Tropical rain forests, page 622. coral reefsHarbor more species per unit area than do tropical rain forests?3. deep sea4. large tropical lakes.B. Coral reefs1. most species rich at 15-30 m depth2. include 32 of the world’s 35 animal phyla3. high primary production, intermediate disturbance, niche specialization4. largest is Australia’s Great Barrier Reef (0.1% of ocean surface area).C. Patterns of diversity1. tropics have greatest diversity of higher taxonomic ranks-- true for marine & terrestrial ecosystems2. species of birds, mammals, trees, & insects increase toward the tropics Diversity declines with latitude.Page 67, Figure 3.33. coniferous trees, salamanders, bees, penguins, waterfowl are most diverse between 20o and 40o latitudeIII. Factors affecting spp richnessA. Terrestrial richness increases with:1. decreasing elevation2. increasing solar radiation3. increasing precipitation4. structural, topographical complexity5. more habitats6. increasing area.B. Island biogeography1. mainlands have more spp. than do islands2. large islands have more spp. than do small islands3. near islands have more spp. than do far islands.C. Why so much tropical diversity?1. more sun, more primary production2. larger area than in temperate zones3. favorable climate4. greater niche partitioning5. biotic interactions prevent competitive exclusion.IV. How do we know what we don’t know?A. Fogging tropical rain forest treesB. Sampling forest soil for nematodes & bacteriaC. Develop “rules” for the # of spp. In biotic relationshipsIn Europe, the # of fungus spp. is 6X that of plant spp. If rule applies globally, then we can expect 1.5 million spp. of fungi.V. Do you want to become a taxonomist?A. Traditional field taxonomists are being replaced by molecular systematistsB. 1500 taxonomists trained in tropical field taxonomyNeed 5X this number for tropical and marine