KETAHANAN EKO- SISTEM Biodiversitas

KETAHANAN

EKO-SISTEM

Biodiversitas

smno.psdl-ppsub.2013

ECOSYSTEM BIODIVERSITY

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

Diunduh dari: plattscience.wikispaces.com/file/.../18.+Biodiversity+in+Ecosystems.p......

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BIODIVERSITAS

• 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:SPESIES & PROSES

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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BIODIVERSITAS

http://en.wikipedia.org/wiki/File:Eaglecreek-28July2006.jpg

Quantifiying this Diversity – Simpson’s Index

D = N (N – 1)∑ n (n – 1)

• Where D = diversity indexN = total # of organisms of all species n = # of individuals of particular species


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• 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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Quantifiying this Diversity – Simpson’s Index

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 areaDiunduh dari:

plattscience.wikispaces.com/file/.../18.+Biodiversity+in+Ecosystems.p...... 19/12/2012

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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Early foxpopulation

Spreadsnorthward

andsouthward

andseparates

Adapted to heatthrough lightweightfur and long ears,

legs, and nose, whichgive off more heat.

Adapted to coldthrough heavierfur, short ears,

short legs, shortnose. White furmatches snowfor camouflage.

Gray Fox

Arctic Fox

Different environmentalconditions lead to different

selective pressures and evolutioninto two different species.

Southern population

Northern population


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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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Time

Small herbsand shrubs

Heath mat Jack pine,black spruce,

and aspen

Balsam fir,paper birch, and

white spruceclimax community

Exposedrocks

Lichensand mosses


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1000

Percentage disturbance

Spec

ies

dive

rsity


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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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Producer to primaryconsumer

Primaryto secondary

consumer

Secondary tohigher-levelconsumer

All producers and

consumers todecomposers

Fungi

Bacteria

Bromeliad

Ants

Tree frog

Green tree snake

Katydid

Climbingmonstera palm

Squirrelmonkeys

Blue andgold

macaw

Harpyeagle Ocelot

Slaty-tailedtrogon

Slaty-tailedtrogon


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Harpyeagle

Tocotoucan

Woolyopossum

Braziliantapir

Black-crownedantpitta

Shrub layer

Canopy

Emergentlayer

UnderstoryUnderstory

Groundlayer

Groundlayer

0

5

10

15

20

25

30

35

40

45H

eigh

t (m

eter

s)


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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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HighwayCleared plotsfor grazing

Cleared plotsfor

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

KETAHANAN EKO- SISTEM Biodiversitas

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