2006 自然科学の英語 -ENS-L8 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 - EvolutionL8

English in Natural Science

自然科学の英語


Biodiversity• Diversity = variety of elements• Biodiversity: multiplicity of species in nature

– Space - biogeography– Habitat - ecology ecosystems– Time - evolution speciation


The tree of life

Prokaryotes3,500 m.y.

MarineSediment

Rocks

Eukaryotes1,800 m.y.

Water

Multicellular540 m.y.

AquaticTerrestrial

Human mind2 m.y

DOMAINS


Taxonomy (Systema Naturae, Carl von Linné 1758)

Kingdom - Animalia• Phylum - Chordata

– Class - Mammalia• Order - Rodentia

– Family - Muridae

» Genus - Apodemus

» Species - sylvaticus

FIVE KINGDOMS• Monera (Prokaryotes)

– Bacteria– Archaea

• Protista (Eukaryotes)• Animalia• Fungi• Plantae

Cladistics: building of evolutionary treeSystematics: phylogenetic classification

Field mouse


More animals than plants


How many species?

• Catalogued1,413,000 (Wilson,1992)

• Estimated10,000 - 30,000

• Unexplored – Rainforest canopy– Bottom of oceans– Soil microorganisms

(After Wilson, 1992)


Phyla distribution on EarthMoist Xeric Benthos Plankton Ecto Endo

Terrestrial 11 4

Freshwater 14 5

Marine 28 12

Symbiotic 11 10

• 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)

(After Grassle, 1991)


Marine benthos Tropical canopy

Phylum Species Families

Cnidaria 19 10

Nemertea 22 1

Priapulida 2 1

Annelida 385 49

Echiurida 4 2

Sipuncula 15 3

Pogonophora 13 5

Mollusca 106 43

Arthropoda 185 40

Bryozoa 1 1

Brachiopoda 2 1

Echinodermata 39 13

Hemichordata 4 1

Chordata 1 1

TOTAL 798 171

Biodiversity 1500-2500 m (Grassle et al., 1991)

Trophic group

Species % host-specific

Estimated host-

specific

Herbivores 682 20 140

Predators 296 5 15

Fungivores 69 10 7

Scavengers 96 5 5

TOTAL 1100 - 160

Beetles on Luehea seemannii (Erwin & Scott, 1980)


Soil ecosystems

Taxa N m-2

Diptera & Coleoptera larvae

2,000

Earthworms 2,000

Enchytraeids 20,000

Springtails 40,000

Mites 120,000

Nematodes 120,000,000

(After Stockl, 1946)

• 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


Measurements of diversity• H’ Alpha diversity

(MacArthur, 1965)– Number of species at one habitat

• H’ Beta diversity (Whittaker 1960, 1977)– The rate at which species

numbers increase between contiguous habitats

– Indicates the change of habitat in an area

• H’ Gamma diversity– Total species in a large territory -

I.e. island, region

• Equitability– Evenness of abundance among

species

Shannon’s diversity index

H’ = -∑pi ln pi

pi = ni/N

Birds in Provence (After Blondel, 1979)X = vegetation complexityY = diversity index


Patterns of diversity

• Species relative abundance (SRA)– Lognormal

distribution• Dominant species• Rare - specialist

species

• Diversity indices– Number of species– Proportion of

individuals

std

of

rela

tive

abun

dan

ce

No. species

(After May, 1988)


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


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


Convergence• Different taxa but similar structure

– Same function in ecosystem

• Pacific island’s woodpeckers

Picidae

Hawaii

Galapagos

New Zealand

Africa 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– Original Krakatau– Nearby mainland


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

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


Island’s biodiversity• Correlated with – Distance from mainland– Area

• No. species doubles for a 10-fold increase in area (MacArthur & Wilson, 1963)

Island Area

(sq miles)

Reptile species

Cuba 44,164 100

Puerto Rico 3,435 40

Montserrat 33 25

Saba 5 10

Redonda 1 5


Evolution of plant biodiversity– Flowering plants (Angiosperms) since Cretaceous– Old taxa remain constant or decrease


Evolution of animal biodiversity– Modern fish (Osteichthyes) since Cretaceous– Modern terrestrial animals (tetrapods) since Tertiary


Historical extinction events

2050

27,000 sp./year74 sp./day


The sixth extinction event - human impactExtinct 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

• Mollusks– 24% in Lake Erie and Ohio rivers (USA)– 100% tree snails in Tahiti

• Plants– 228/20,000 in USA (680 endangered)– 40-50% fungi in Europe (Netherlands, Germany)

HIPPOHabitat destruction 88%Invasive species 46%Population (human)

Pollution 20%Overkilling 14%


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)


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


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 speciesA area

C constantz constant

0.15 < z < 0.35Low z dispersal ability (birds, etc)

High z immobile (plants)

z Area (%) Species (%)

0.15 50 10

0.30 50 19

0.35 50 22

Predicted losses by 2022 (Wilson, 1992)


Biodiversity ‘Hot spots’ (Myers, 1988)

Hawaii New Caledonia

California

Colombian ChocoWestern Ecuador

Uplands W AmazonAtlantic Coast Brazil

Central Chile

Ivory Coast

Cape Province

TanzaniaMadagascar

SW Australia

W GhatsSri Lanka

E Himalayas

Malaysia + N BorneoPhilippines

1.3% Land 40% plants + 25% vertebrates


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• Rabbits and foxes in Australia• Blackbass in Japan• Nile perch in Lake Victoria (Tanzania)

50% of endemic cichlid fish extinct

% plant species

USA 11

Ontario 28

Britain 43

Hawaii 44

Japan ?

JapanInvasive Alien Species Act

Effective June 2005

Prohibition to import 11 mammals

4 birds6 reptiles

1 amphibian4 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– Planktonic, benthic and soil communities– Forests (air pollution)

2006 自然科学の英語 -ENS-L8(After Wilson, 1992)

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)


Human population

• Humanity appropriates 20-40% world bio-resources (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


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”


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)


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

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2006 自然科学の英語 -ENS-L8 Biodiversity - Evolution L8 English in Natural Science 自然科学の英語