Transcript Biodiversity

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
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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
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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
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More animals than plants
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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
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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)
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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
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Trophic
group
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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
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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
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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)
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– 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
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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
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Convergence
• Different taxa but similar structure
– Same function in ecosystem
• Pacific island’s woodpeckers
Picidae
Hawaii
Galapagos
New Zealand
Africa
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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
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– Original Krakatau
– Nearby mainland
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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
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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
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Island’s biodiversity
• Correlated with
– Distance from mainland
– Area
• No. species doubles
for a 10-fold increase
in area (MacArthur &
Wilson, 1963)
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Island
Area
(sq miles)
Reptile
species
Cuba
44,164
100
Puerto Rico
3,435
40
Montserrat
33
25
Saba
5
10
Redonda
1
5
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Evolution of plant biodiversity
– Flowering plants (Angiosperms) since Cretaceous
– Old taxa remain constant or decrease
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Evolution of animal biodiversity
– Modern fish (Osteichthyes) since Cretaceous
– Modern terrestrial animals (tetrapods) since Tertiary
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Historical extinction events
27,000 sp./year
74 sp./day
2050
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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)
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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)
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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
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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
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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
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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
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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
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• Rabbits and foxes in Australia
• Blackbass in Japan
• Nile perch in Lake Victoria (Tanzania)
50% of endemic cichlid
fish extinct
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% 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
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– Planktonic, benthic and soil communities
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– 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)
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(After Wilson, 1992)
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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
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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”
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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)
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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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