Transcript Genetic diversity

KETAHANAN
EKOSISTEM
Biodiversitas
smno.psdl-ppsub.2013
ECOSYSTEM
BIODIVERSITY
BIODIVERSITAS
1. Biodiversity = the amount of biological or
living diversity per unit area. It includes
the concepts of species diversity, genetic
diversity and habitat diversity
2. Genetic diversity = the range of genetic
material present in a gene pool or
population of a species
3. Species diversity = variety among species
per unit area. Includes both the number
of species present and their abundance.
4. Habitat diversity = The range of different
habitats or number of ecological niches
per unit area in an ecosystem, community
or biome. Conservation of habitat
diversity usually leads to conservation of
species and genetic diversity
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BIODIVERSITAS:
SPESIES & PROSES
• Is key to the overall function of
earth
• In general Diversity = Stability
• Biodiversity is
– Nature’s insurance policy against
change
– The source of all natural capital for
human use
– The way chemical materials are cycled
and purified
– The end result of millions of years of
evolution and irreplaceable
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BIODIVERSITAS
1.
Richness: The number of species per sample is a
measure of richness.
 The more species present in a sample, the
“richer” the sample.
2. Evenness: A measure of the relative abundance
of the different species making up the richness
of an area.
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Quantifiying this Diversity –
Simpson’s Index
D = N (N – 1)
∑ n (n – 1)
• Where D = diversity index
N = total # of organisms of all species
n = # of individuals of particular species
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Quantifiying this Diversity –
Simpson’s Index
• High values of “D” suggests a stable
and ancient site
• A low value of “D” could suggest
pollution, recent colonization, or
agricultural management
• Index normally used in studies of
vegetation but can be applied to
comparisons of diversity of any
species
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How does diversity exist?
• Natural Selection = survival of the fittest
• Fitness = a measure of reproductive
success
• If all individuals are variable
• And populations produce large numbers
of offspring without increase in
population size
• And resources are limited
• And traits are heritable
• Then those individuals who are best
adapted to the environment will survive
and pass on their genes
• Gradually the gene frequency in the
population will represent more of these
“fit” individuals
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SELEKSI ALAMIAH
• Environmental Pressures select for
some genotypes over others
• Alleles resulting in a beneficial trait
will become more common
• Heritable traits that increase survival
chances are called adaptations
• There are many niches or habitats
and roles available in the
environment
• As populations adapt they fill new
niches and over time may develop
into new species
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Speciation
• Certain circumstances lead to the
production of new species through natural
selection
• Most common mechanism has 2 phases 
geographic followed by reproductive
isolation
1. Geographic isolation  groups of a
population of the same species are isolated
for long periods
– A group may migrate in search of food to an
area with different environmental conditions
– Populations may be separated by a physical
barrier (mountain range, river, road)
– Catastrophic change by volcano eruption or
earthquake
– A few individuals carried away by wind or water
to new area
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Speciation 2
2. Reproductive Isolation  mutation and
natural selection operate independently
on the 2 populations to change allele
frequencies = divergence
• If divergence continues long enough
genetic differences may prohibit (1)
interbreeding between populations
and/or (2) production of viable, fertile
offspring
• One species has become 2 through
divergent evolution
• For most species this would take millions
of years
• Difficult to document & prove this
process
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Northern population
Adapted to cold
through heavier
fur, short ears,
short legs, short
nose. White fur
matches snow
for camouflage.
Arctic Fox
Early fox
population
Spreads
northward
Different environmental
and
conditions lead to different
southward
selective pressures and evolution
and
into two different species.
separates
Southern population
Adapted to he
through lightwe
fur and long ea
legs, and nose, w
give off more h
Gray Fox
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Consequences of Plate
Activity
• Speciation processes rely on
physical separation of organisms
• Plate techtonics
– can lead to separation of gene pools
– mountain ranges form, faults
separating land masses
– Can link species and land areas e.g.
land bridges
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Consequences of Plate Activity II
• Plate techtonics generates new
habitats
– Island chains over hotspots – Hawaii
– Mountain habitats – Himalayan
mountains – also associated effects on
surrounding areas
– Hydrothermal vent communities
– Changes climate on land masses –
continents drift into new climate zones
 e.g. antarctica was once covered by
tropical rainforest now barren polar ice
fields
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1. Succession effects
Diversity
• Succession – gradual establishment or
reestablishment of ecosystems over
time
• Pioneer species  Climax species
– Low diversity at first, few species can
tolerate harsh conditions (r selected
species)
– Most diverse in middle of succession,
slower growing species start to fill in
– Low diversity at the end, climax species
often strongest competitors (K selected
species)
• Diversity is a function of disturbance
 intermediate disturbance
hypothesis
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Lichens
and mosses
Balsam fir,
paper birch, and
white spruce
climax community
Exposed
rocks
Heath mat
Jack pine,
black spruce,
and aspen
Small herbs
and shrubs
Time
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Species diversity
0
100
Percentage disturbance
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2. Habitat diversity influences
species & genetic diversity
• More complex areas (more
diverse habitats) often have
higher species & genetic diversity
• Ex. Tropical rainforest & Coral reef
• In both cases, high degree of
structural / spatial complexity
• Promotes coexistence by niche
partitioning & diversification
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Harpy
eagle
Blue and
gold
macaw
Ocelot
Producer
to primary
consumer
Primary
to secondary
consumer
Squirrel
monkeys
Climbing
monstera palm
Slaty-tailed
trogon
Katydid
Green tree snake
Secondary to
higher-level
consumer
Tree frog
All producers
and
consumers to
decomposers
Ants
Bromeliad
Fungi
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Bacteria
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45
40
Emergent
layer
Harpy
eagle
35
Toco
toucan
Canopy
Height (meters)
30
25
20
Understory
Wooly
opossum
15
10
Brazilian
tapir
5
Black-crowned
antpitta
0
Shrub layer
Ground
Ground
layerlayer
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Complex ecosystems with a variety of
nutrient & energy pathways provides
stability
• Energy is key to the function of all
ecosystems
• Biogeochemical cycles recycle
necessary materials through
system
• More pathways for energy &
matter = more stable
• Insurance against natural or
human changes
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Aktivitas Manusia
• Modify succession by adding
disturbance
• Logging, Grazing, Burning – all
prevent natural successional
processes
• Fragmenting habitats by
development
• Isolate populations  more likely to
get diseases, succumb to local
disturbances
• We simplify ecosystems  tall grass
prairie converted to wheat farms 
more vulnerable
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Cleared plots
for grazing
Highway
Cleared
plots
for
agriculture
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Any ecosystem’s capacity to survive
change may depend on its diversity,
resilience, and inertia
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Biodiversitas
Agroekosistem