Transcript BIODIVERSITY: AN INTRODUCTION Warren Y. Brockelman …

Web-based Course
วิชา ความหลากหลายทางชีวภาพในประเทศไทย
(Biodiversity in Thailand)
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สถาบันบัณฑิตวิทยาศาสตร์ และเทคโนโลยีไทย (สบวท.)
Thailand Graduate Institute of Science
and Technology (TGIST)
www.learn.in.th
[email protected]
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สำนักงำนพัฒนำวิทยำศำสตร์ และเทคโนโลยีแห่ งชำติ
National Science and Technology Development Agency
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Prof. Dr. Warren Y. Brockelman
Mahidol University
Bangkok, Thailand
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Biodiversity
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Genetics
Evolution
Ecology
Taxonomy
Environmental Sciences
Molecular biology
Biotechnology
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Causes of Extinction of Species
• Habitat destruction
• Pollution
• Over Hunting
Current Rate of over Extinction ~ 1000 times the Natural Rate
(Natural Rate ~1 per 1-10 million species /year)
The majority of species will become extinct
before we will able to study or use them
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“Biodiversity”
= all the systems of living things
(DNA, genes, individuals, species,
communities, and ecosystems)
Saving as many species as possible
The improvement of our lives and our
very survival (biotechnology, genetic
engineering, ecosystem function,
beauty, ...)
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Food diversity
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Hidden products
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Speicies diversity
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Genes to ecosystems
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Within species diversity
• Genetic variation
• Races
• Subspecies (geographic variation)
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Genetic Variation:
• Each individual is genetically distinct
• Measured by detecting variation in
enzymes or proteins (direct products of
genes)
• Measured by analyzing for differences in
nucleotide sequences
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Ecosystem Variability:
= the differences in structure,
productivity and nutrient cycles in
communities in different types of
environment and climatic zones of
the Earth
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Ecosystem function is vital to all living things
Nitrogen cycle
Carbon cycle
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History of Life
3.7 billion years
3.6 billion years
2.5 billion years
400 Mya
300 Mya
150 Mya
65 Mya
2 Mya
The first living things
aquatic cyanobacteria
planktonic plants (O2)
fishes
land plants, insects
amphibians, reptiles
first birds, mammals
mammal radiations
primitive humans
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History of the Earth (continue)
245 Mya
65 Mya
The regign of dinosaurs, until
their extinction caused by
collision of a large asteroid
with Earth
But normal rate of
extinction approximately
1 species per 1-10 million
per year
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Evolution over millions of years
• Changes in populations through time
• Speciation (branching) , due to
•Separation (geographic speciation)
•Reproductive isolation
Species diversity
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Species: distinct types of organisms with
reproductively separate populations
Each species: has distinct scientific name
(Genus and species name)
We are: Homo Sapiens
Number of species in an areas is
the most useful measure of biodiversity
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How many species are there
on Earth ?
5 to over 15 million species
But only 1.5 million species have been described so far
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insects
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vertebrates
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vascular plants
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invertebrates
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fungi and microorganisms
2/3 of all species
40,000 species
270,000 species
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Charles Darwin Era (Natural Selection):
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Individual Variation
Inheritance from parents to offspring
Population growth and competition
Survival of the fittest
Evolutionary Change
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Important genetic
principles
•Particulate inheritance
•“Genes” come in pairs
•Dominance
•Independent assortment
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Quantitative inheritance
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By 2000: Genetics, Molecular Biology
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genes and chromosomes
mutation
recombination
gene frequencies and selection
DNA structure and replication
transcription (protein formation)
nucleotide sequence
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DNA codes
for proteins
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A continuing controversy :
Is evolution gradual or sudden?
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Genetic analysis reveals phylogeny
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99% of all species that
ever evolued
are now extinct
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The study of biodiversity
above the species level
• Population study
• Ecological communities
• Interactions (Stability & Diversity of communities)
- herbivores and plants
- predators and prey
- trees and seed dispersers
- pollinators and plants
- fungi and roots
• Ecosystem function and diversity
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Communities consist of many interactions
Nutrients
plants
herbivores
predator
diseases
decomposer
dispersal
migration
genetic change
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The flow of energy
through a
community
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Species diversity in a community
Number of species on islands affected by:
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Local extinction
Colonization of immigrants
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Causes of Extinction
• Fragmented forest
• Small species population sizes
Species at most risk of extinction
•Low rate of population increase
•Poor dispersal ability
•Low natural density
•Hunted for their valuable parts
•In vanishing habitats
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Causes of Species loss
Half the species on Earth (by next few centuries)
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Tropical forest destruction
Forest fragmentation
Hunting
Pollution
Damming and Canalization of rivers
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Why save species?:
Because
• Direct use to humans
• Maintain ecosystems for survival of humans
If we lose species
•cannot be recreated
•loss of potential values or uses:
food
chemicals
genes
natural beauty
ecosystem stability
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How to slow down the extinction of species
• Reduction of human population increase
• Conservation of natural ecosystems as
“ protected areas”
• Reduction of rural poverty
• Special breeding programs for critical species
• Reduction of pollution and disturbance of rivers
• Diversification of forestry and agriculture to
reduce monocultures
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Why save biodiversity?
The answer is:
you tell us!
Why do you want to save it?
Some general reasons
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Because it pays. Many people make a living
harvesting plants and animals, and using wildlife also.
While this may not apply to you, it is wrong to destroy
animals and plants that others need to make their living
from.
Because we are part of an ecosystem that sustains
us, by providing services such as clean water and air,
rainfall, fertile soil, and pest control. Destroying
animals and plants will ultimately harm us.
We do not have a natural right to destroy
anything in nature, any more than we have a right
to kill other people.
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