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Biodiversity - Evolution L8 English in Natural Science 自然科学の英語 2006 自然科学の英語-ENS-L8 Biodiversity • Diversity = variety of elements • Biodiversity: multiplicity of species in nature – Space - biogeography – Habitat - ecology ecosystems – Time - evolution speciation 2006 自然科学の英語-ENS-L8 The tree of life Multicellular 540 m.y. Eukaryotes 1,800 m.y. Aquatic Terrestrial Water Prokaryotes 3,500 m.y. Human mind 2 m.y Marine Sediment Rocks DOMAINS 2006 自然科学の英語-ENS-L8 Taxonomy (Systema Naturae, Carl von Linné 1758) FIVE KINGDOMS • Monera (Prokaryotes) – Bacteria – Archaea • • • • Kingdom - Animalia • Phylum - Chordata – Class - Mammalia • Order - Rodentia Protista (Eukaryotes) Animalia Fungi Plantae – Family - Muridae » Genus - Apodemus » Species - sylvaticus Field mouse Cladistics: building of evolutionary tree Systematics: phylogenetic classification 2006 自然科学の英語-ENS-L8 More animals than plants 2006 自然科学の英語-ENS-L8 How many species? (After Wilson, 1992) • Catalogued 1,413,000 (Wilson,1992) • Estimated 10,000 - 30,000 • Unexplored – Rainforest canopy – Bottom of oceans – Soil microorganisms 2006 自然科学の英語-ENS-L8 Phyla distribution on Earth Terrestrial Moist Xeric 11 4 Benthos Plankton Freshwater 14 5 Marine 28 12 Symbiotic Ecto Endo 11 10 (After Grassle, 1991) • Marine ecosystems contain all existing phyla – Benthic organisms are the most diverse in structure and function – Living organisms originated in marine sediments • Terrestrial organisms are modern (<540 m.y. old) – Comprise 1/3 of all existing phyla • Plants - photosynthesis advantageous on land • Most insects (adapted to dry environments - xeric) 2006 自然科学の英語-ENS-L8 Marine benthos Tropical canopy Biodiversity 1500-2500 m (Grassle et al., 1991) Beetles on Luehea seemannii (Erwin & Scott, 1980) Species % hostspecific Estimated hostspecific Herbivores 682 20 140 Predators 296 5 15 Fungivores 69 10 7 3 Scavengers 96 5 5 13 5 TOTAL 1100 - 160 Mollusca 106 43 Arthropoda 185 40 Bryozoa 1 1 Brachiopoda 2 1 Echinodermata 39 13 Hemichordata 4 1 Chordata 1 1 798 171 Phylum Species Families Cnidaria 19 10 Nemertea 22 1 Priapulida 2 1 Annelida 385 49 Echiurida 4 2 Sipuncula 15 Pogonophora TOTAL 2006 Trophic group 自然科学の英語-ENS-L8 Soil ecosystems • Soil is produced by the interaction of biota and surface of the Earth • Micro-ecosystem within an ecosystem • Essential role in recycling and decontamination of matter Taxa N m-2 Diptera & Coleoptera larvae 2,000 Earthworms 2,000 Enchytraeids 20,000 Springtails 40,000 Mites 120,000 Nematodes 2006 自然科学の英語-ENS-L8 120,000,000 (After Stockl, 1946) Measurements of diversity • H’a Alpha diversity (MacArthur, 1965) Birds in Provence (After Blondel, 1979) X = vegetation complexity Y = diversity index – Number of species at one habitat • H’b Beta diversity (Whittaker 1960, 1977) – The rate at which species numbers increase between contiguous habitats – Indicates the change of habitat in an area • H’g Gamma diversity – Total species in a large territory I.e. island, region Shannon’s diversity index • Equitability – Evenness of abundance among species 2006 自然科学の英語-ENS-L8 H’ = -∑pi ln pi pi = ni/N Patterns of diversity std of relative abundance • Species relative abundance (SRA) – Lognormal distribution • Dominant species • Rare - specialist species • Diversity indices No. species (After May, 1988) 2006 – Number of species – Proportion of individuals 自然科学の英語-ENS-L8 Evolution and speciation • Biodiversity changes - Geological eras and periods – Extinction of old forms & apparition of new ones – Environment is the theatre and evolution the play • Evolutionary forces – Natural selection of adaptations (Darwin & Wallace, 1859) • Genetic modification - mutations • Survival of the fittest – Isolation - allopatric speciation • Reproduction – Split populations • Continental drift & island formation • Habitat segregation (i.e. mountains) – Adaptive radiation - sympatric speciation • small populations several niches 2006 自然科学の英語-ENS-L8 Sympatric speciation • A single population occupies all niches – Adaptation to a niche • Specialization • Reproductive isolation – Segregation into several species • Within islands, lakes, oceans – Galapagos finches (~13 sp.) – Hawaii honeycreepers – Cichlidae fish (~300 sp. lake Victoria, Tanzania) – Sharks (~350 sp.) • Host-parasites 2006 自然科学の英語-ENS-L8 Convergence • Different taxa but similar structure – Same function in ecosystem • Pacific island’s woodpeckers Picidae Hawaii Galapagos New Zealand Africa 2006 自然科学の英語-ENS-L8 South America Colonization • August 27,1883 – eruption of Krakatau (Sunda strait, Indonesia) • Colonists in order of appearance – Spiders – Aerial plankton (72 species in 10 days) • animals, spores, Compositae seeds – Birds, bats – Seeds, parasites – Aquatic reptiles • Succession of extinctions and replacements • Final ecosystem very different from 2006 – Original Krakatau – Nearby mainland 自然科学の英語-ENS-L8 What determines biodiversity? • Energy in ecosystems – Tropical > temperate > polar • Large areas – Continents > Islands – Large forest > small forest • Continental break-up – Since Cretaceous – Increased variety of environments – Fostered evolution 2006 Latitude Bird species Greenland 65 56 Labrador 48 81 New York State 41 195 Guatemala 15 469 Colombia 6 1,525 Diversity of niches + Stable populations (no extinction) in Complex ecosystems 自然科学の英語-ENS-L8 Island’s biodiversity • Correlated with – Distance from mainland – Area • No. species doubles for a 10-fold increase in area (MacArthur & Wilson, 1963) 2006 Island Area (sq miles) Reptile species Cuba 44,164 100 Puerto Rico 3,435 40 Montserrat 33 25 Saba 5 10 Redonda 1 5 自然科学の英語-ENS-L8 Evolution of plant biodiversity – Flowering plants (Angiosperms) since Cretaceous – Old taxa remain constant or decrease 2006 自然科学の英語-ENS-L8 Evolution of animal biodiversity – Modern fish (Osteichthyes) since Cretaceous – Modern terrestrial animals (tetrapods) since Tertiary 2006 自然科学の英語-ENS-L8 Historical extinction events 27,000 sp./year 74 sp./day 2050 2006 自然科学の英語-ENS-L8 The sixth extinction event - human impact Extinct species: not seen in 50 years • 73% mammals in America gone (10,000 y) • 1/5 birds (2000 y) from11,000 9,040 current species) – Pacific Islands (25-60%) – Songbirds Eastern USA: 50% populations from 1940-1980 • 20% freshwater fish – Malaysia (46%), Lake Victoria (50%), Lake Lanao - Philippines (83%) • Invertebrates – 17-34% endangered in Europe HIPPO Habitat destruction 88% • Mollusks Invasive species 46% – 24% in Lake Erie and Ohio rivers (USA) Population (human) – 100% tree snails in Tahiti Pollution 20% • Plants Overkilling 14% – 228/20,000 in USA (680 endangered) – 40-50% fungi in Europe (Netherlands, Germany) 2006 自然科学の英語-ENS-L8 Coral reefs • Survived through 500 millions of years – Historical changes of sea level (glacial periods) – Natural catastrophes (volcanic, tsunamis) – El Niño fluctuations (typhoons) • Now dying – 10% most places – 30% Florida • Main causes – Climate change & pollution – Coral bleaching • Zooxanthellae lost due to pollutants and high water temperature – Predation by star of thorns (Australia Great Barrier Reef) 2006 自然科学の英語-ENS-L8 Habitat destruction 1979: 56% tropical rainforest – Rate: 75,000 km-2/y (1%) 1989: 8 m km2 left (<50%) – Rate: 142,000 km-2/y (1.8%) CAUSES • Small farming (poverty) – Slash-and-burn cultivation air pollution – Soya beans, palm oil, coca • Commercial logging • Cattle 2006 自然科学の英語-ENS-L8 Why are rainforest so important? • Storage of CO2 – Unlike temperate forest, all carbon is stored in plant tissues (timber, roots) • Refuges of biodiversity – Species per area >>> temperate forest – Untapped source of medicines, useful products S = C Az S number species A area C constant z constant 2006 0.15 < z < 0.35 Low z dispersal ability (birds, etc) High z immobile (plants) Predicted losses by 2022 (Wilson, 1992) z Area (%) Species (%) 0.15 50 10 0.30 50 19 0.35 50 22 自然科学の英語-ENS-L8 Biodiversity ‘Hot spots’ (Myers, 1988) 1.3% Land 40% plants + 25% vertebrates Ivory Coast Tanzania Colombian Choco Madagascar Hawaii Cape Province E Himalayas New Caledonia Western Ecuador California Philippines Uplands W Amazon W Ghats Atlantic Coast Brazil Sri Lanka Malaysia + N Borneo Central Chile SW Australia 2006 自然科学の英語-ENS-L8 Invasive species • Damage – Pests and weeds out of control – Competition native population – Extinction of native species • Routes – Transportation (ship) • Norwegian rat, mice, ants, spiders, seeds (sheep), diseases – Pet traders (black market) • Snakes, toads, crocodiles, birds – Sport 2006 • Rabbits and foxes in Australia • Blackbass in Japan • Nile perch in Lake Victoria (Tanzania) 50% of endemic cichlid fish extinct 自然科学の英語-ENS-L8 % plant species USA 11 Ontario 28 Britain 43 Hawaii 44 Japan ? Japan Invasive Alien Species Act Effective June 2005 Prohibition to import 11 mammals 4 birds 6 reptiles 1 amphibian 4 fish 3 insects (ants) 10 invertebrates (spiders) 3 plants Pollution • 38% of extinctions - weaken organisms • Aquatic ecosystems more affected than terrestrial – Continuous exposure (gill filtering) and accumulation – Less ability to degrade pollutants (oxidases) • Main effects – Direct mortality of individuals • toxicity (pesticides, PCBs, industrial chemicals, heavy metals) – Endocrine disruption • organochlorines, pharmaceuticals, hormones – Malformations and cancer • dioxins, PCBs, heavy metals – Stress - diseases • Habitat transformation 2006 – Planktonic, benthic and soil communities 自然科学の英語-ENS-L8 – Forests (air pollution) Overkilling • The big, the slow and the tasty • Australia (30,000 y) – 80% marsupials (giant) • North America (12,000 y) – 73% mammals • Mammoth, horse, tapir, ground sloth, camel, antelopes, bison • Indian-Pacific islands (3,000 y) – Flightless birds (moa, Aepornis, rails, dodo) 2006 (After Wilson, 1992) 自然科学の英語-ENS-L8 Human population • Humanity appropriates 20-40% world bioresources (solar energy) – Use 30% of productivity of all ecosystems Human biomass animals biomass 350 m tons + - 350 m tons • Increase rate: 70 million people/ year • Bleak future – Unsustainable for both humanity and nature – After exhausting natural capacity CRASH !!! – Inevitably we are digging our own graves 2006 自然科学の英語-ENS-L8 Environmental ethics • Practical reasons – Natural resources are essential for our lives • food, medicines (40% pharmaceuticals) • clean air and water • Ethical reasons – We are not aliens on Earth: we come from it and depend on it for our living – We have no right to destroy what we have not created • Natural world belongs to the Creator • We use it, but DO NOT destroy it – We have to know more… “The better an ecosystem is known, the less likely it will be destroyed” 2006 自然科学の英語-ENS-L8 Epitaph “The ultimate irony of organic evolution: that in the instant of achieving self-understanding through the mind of man, life has doomed its most beautiful creations. And thus humanity closes the door to its past” (Wilson, 1992) “In the end, we will conserve only what we love, we will love only what we understand, we will understand only what we are taught” (Baba Dioum, Senegal) 2006 自然科学の英語-ENS-L8 References • Edward O. Wilson. 1992. The diversity of life / 園芸-応用動物昆虫学 B-226 • Edward O. Wilson. 2002. The future of life /B-226 • Paul Davies. 2000. The origin of life / B-226 • Robert M.May 1988. How many species are there on Earth. Science 241: 1441-1449. http://www.h.chiba-u.jp/english/Education/ENS_H12001/ENS.htm 2006 自然科学の英語-ENS-L8