2. Threats to biological diversity
A healthy environment has great economic, aesthetic and ethical value,
maintaining a healthy environment means preserving all of its components in
good condition:
Ecosystem
Communities and
Species
The most serious aspect of environmental damage is the extinction of species.
Communities an be degraded and reduced in area but long as all of the original
species survive, communities still have the potential to recover.
As a result of such reasons genetic variation with in a species will be reduced as
population size is lower ed but species can potentially regain genetic variations
through
Mutation
Natural selection
Recombination.
3. Threats to biological diversity
However, once a species is eliminated, the unique genetic information
contained in its DNA. The special combination of characters that it possesses
are forever lost.
Once a species goes extinct, its population s can not be restored.
The communities that it inhabited are impoverished and its potential value to
humans can never be realized.
Extinct
A species is considered extinct when no member of the species remain alive
any where in the world:” the Bachman’ s warbler extinct”. There are
following situation in which a specie will extinct.
Locally extinct a species is considered locally extinct when it is no
longer found in an area that it once inhabited but it still found
elsewhere in the wild. E.g. American burying beetle once occurred
throughout eastern and central North America ; it is locally extinct in all
but three widly separated area.
4. Threats to biological diversity
Ecologically extinct.
If a species persists at such reduced number that its effects on the other
species in its community are negligible; e.g. the tiger is ecological
extinct so few tigers remain in the wild that their effect on prey
population is significant.
Globally extinct
If individuals of a species remain alive only in captivity or in other human
controlled conditions, the species is said to be extinct in wild . E.g. the
Franklin tree is extinct in wild but grows well under cultivation. In both
of these situations the species would be considered globally extinct.
5. Threats to biological diversity
Living dead
In some populations a few individuals might persist for years ar
decades and even reproduce, but their ultimate fate would be
extinction .in woody plants in particular ,isolated non
reproductive individuals can persist for hundreds of years these
species have been called “the living dead “
Technically the species is not extinct while a few individuals liv
The population is no longer viablr
The species’s future is limited to life spans of the remaining
individuals.
6. Threats to biological diversity
Factor affecting on the preserved species.
In order to successfully preserved species , conservation biologists must
identify the human activities that affect the sustainability of
populations and drive species to extinction. They must also determine
the factors that make a population vulnerable to extinction.
Types of extinction
Human caused extinction
The global diversity of species reached an all time high in the present
geological period
The most advanced groups of organisms ,insects ,vertebrates and
flowering plants reached their great diversity about 30000 years ago.
Species richness has decreased as the human populations have grown.
In present time a phenomenal 40% of not yet technically extinct have
been decimated by human activities and pesist only in very low numbers.
7. Threats to biological diversity
These species may be considered ecologically exctinct in that they no
longer play a role in community organization .
the future of many species is doubtful.
About 11% of the world’s remaining bird species are threatened with
extinction the same percentage in mammals
Lizards, freshwater fishes and mollusks may be equally sever
endangered.
Extinction rate on islands
Most of the known extinctions of birds, mammals and reptiles during
the last 350 years have occurred on islands.
More than 80% of the endemic plants of some oceanic islands are extinct
or in danger of extinction .
Island species are particularly vulnerable to extinction because many of
them are endemic to only one or a few local populations.
8. Threats to biological diversity
Rate of extinction in tropical rain forests
The tropical moist forests are spectacularly rich in endemic
species 93% of the 28 primates
99% of the 144 species of frogs
Over 80% of the plant species on the island are endemic to the
Madagascar.
Only 33% of the plants species are endemic to Europe now else.
factors
1. Geological age
2. A wide variety of habitats
9. Threats to biological diversity
Rate of extinction on Hawaiian Archipelago
a. There are 98 species of endemic birds in Hawaiian islands beforeb the arrival of the
Polynesians in 400 AD.
Polynesians introduced
Rat,
The endemic dog
The domestic pigs
Began clearing the forest for agriculture
Extinctions
1) Result of increased predation and disturbance about 50 species of bird species become
extinct.
European involvements
They introduced
Rats
Cats
Indian mongoose
Goats
Cattle
Barn owl
10. Threats to biological diversity
They also unwittingly brought bird diseases.
They clear even more land for agriculture and
Threats to biological diversity
17 bird species have become extinct.
Remaining endemic species have declining population and are near to
extinction.
Many land species are also threatened with extinction
Causes of extinction
1) Massive disturbance
i. Massive disturbance caused by people have altered degraded and
detroyed the land scape on a vast scale driving species and even whole
communities to the point of extinction.
11. Threats to biological diversity
ii. The major threats to the biodiversity that result from human activity as
1) Habitat destruction
2) Habitat fragmentation
3) Habitat degradation
4) The over exploitation of species for human use
5) Introduction of exotic species and increased spread of diseases.
2) Problems for species
Most threatened species face at least two or more problems which are
speeding their way to extinction and hindering efforts to protect
them.
i. Exploitation of the human population
ii. Loss of habitat.
12. Threats to biological diversity
3) Over use of natural resources
People use natural resources such as
i. Fuel wood
ii. Wild meat
iii. Wild plants
People convert vast amounts of natural habitat to agricultural and
residential purposes so the growth of human population is reposible for
the loss of biodiversity.
4) Industrial revolution
The rise of industrial capitalism and materialistic modern societies has
produced an accelerated demand for natural resources particularly in
the developed countries. Inefficient and unequal usage of natural
resources is also a major cause of decline in biodeversity.
13. Threats to biological diversity
Causes
i. Unequal distribution of wealth
ii. Rural people forced to destroy biological communities
iii. Hunting the endangered species by poor .
5) Habitat destruction
In many cases the causes of habitat destruction are large scale industrial
and commercial activities associated with a global economy such as
i. Mining
ii. Cattle ranching
iii. Dam construction
iv. Commercial fishing
v. Forestry
vi. Plantation agriculture manufacturing
14. Threats to biological diversity
Causes
a. Unequal use of natural resources
b. Consuming disproportionate share of the world energy, minerals,
wood product, and food.
Industrial revolution stars after
Babonic plague 1348
15. Threats to biological diversity
Human population exploitation period
The greatest destruction of biological communities during last 150 years.
During which the human population grew from
a) 1 billion in 1850
b) 2 billion in 1930
c) 5.9 billion in 1965
d) 6.5 billion in 2000
Causes
a) Human population increases because of the mortality rat is slow the
rate of birth
b) Mortality rate is low because of modern medical discoveries.
16. Threats to biological diversity
6)Habitat fragmentation
Habitat fragmentation us the process where by a large , continuous area of
habitat is both reduced in area and divided into or more fragments .
Conditions of habitat fragmentation
These fragmentation are often isolated from one another by highly
modified or degraded landscape. This situation can be described by the
islands in an inhospitable human-dominated “sea”.
Fragmentation occurs during almost any severe reduction in habitat
area , but it can also occur even when habitat area is reduced to only a
minor degree as when the original habitat is divided by roads , railways,
canals, power lines , fences, oil pipelines, fire lanes or other barriers to
free movement of species.
17. Threats to biological diversity
Habitat fragmentation threats
A. First fragmentation may limit a species potential for dispersal
and colonization. Many birds , mammals and insects species of
the forest interior will not cross even very short stretches of
open area because of the danger of predation.
B. A second harmful aspect of the habitat fragmentation is that it
may reduce the foraging ability of native animals. Many animal
species either as individuals or as social groups need to be able
to move freely across the land scape among widely scattered or
seasonally available resources.
18. Threats to biological diversity
Edge effects
Habitat fragmentation dramatically increases the amount of edge
relative to the amount of interior habitat. The microenvironment at
fragment edge is different from that of the forest interior .Some of
these edges effects are more important as
a) Greater fluctuations in levels of light
b) Temperature
c) Humidity
d) Wind
These edge effects are often evident up to 500 meters into the forest
because plant and animal species are often precisely adapted to
certain temperature ,humidity, and light levels , these changes will
eliminate many species from forest fragments.
19. Threats to biological diversity
Habitat degradation and pollution
Causes
Frequent uncontrolled ground fires.
Most subtle form of degradation is environmental pollution.
Frequent boating and diving in coral reef area typically degrade
the community as fragile species are crushed by diver's flippers
,boat hulls, and anchors.
The general effects of pollution on water quality , air quality,
global climate having great concern to the biological threats.
Massive oil spills
20. Threats to biological diversity
Pesticide pollution
The danger of pesticides were brought to the world's attention in 1962 by
Rachel Cartson’s influential book “Silent Spring”.
DDT effects on the soil water and food products.
Use of organochlorine pesticides .
Effects of pesticides
a) Pests develop resistance against such pesticides as above.
b) DDT over dose create serious results not only insect , birds but on
the human own self.
Out comes
i. By banning DDT , we are able to partially recover many bird species,
most notably peregrine falcons, ospreys and bald eagles.
21. Threats to biological diversity
ii) the continuing use of these pesticides in other
countries is cause for concern not only for the
sake of endangered animal species but also
because of their potential long term effects on
people .
Water pollution
Water pollution has negative consequences for human populations it
destroys food sources such as
i. Fish
ii. Shellfish
iii. Contaminates drinking water
iv. Affect the other water communities
22. Threats to biological diversity
Causes
a. Open sewers to water reserves for industrial wastes
b. Residential sewage.
c. Pesticides
d. Herbicides
e. Petroleum waste
f. Spills
g. Heavy metals
h. Detergents
Human activities for sharing damage to the environment
Human sewage agricultural and lawn fertilizers , detergents and industrial
processes often release large amounts of nitrates and phosphates into
aquatic systems, starting a process known as cultural eutrophication.
23. Threats to biological diversity
Air pollution
the human activity has alter and contaminated the earth’s atmosphere. In the
past people assumed that the atmosphere was so vast that materials
released into the air would be widely dispersed and their effects would be
minimal but today several types of air pollution are damaging ecosystems .
Acid rain (the acid are incorporated into cloud systems and dramatically
lower the pH of the rain water).
Effects
Decline in water pH cause a corresponding increase in the mortality of eggs
,larvae,.
Acidity also inhibit the microbial activity
Minimize the mineral the recycling and ecosystem productivity.
Pond , lakes and river bodies have lost large portion of their animal
communities.
24. Threats to biological diversity
Ozone production and nitrogen deposition
Causes
Automobiles
Power plants
Industrial activities
Hydrocarbons and nitrogen oxides as waste products
Photochemical smog.
In the presence of sunlight ,these chemicals react with atmosphere
to produce ozone and other secondary chemicals collectively
called photo chemical smog.
25. Threats to biological diversity
Toxic metals (leaded gasoline, mining , smelting operations and
other industrial activities release large quantities of lead, zinc,
and other toxic metals in to atmosphere).
Effects
a) Forest has great economic value as they are wood producers ,
they effect by such damages
b) water shed management
c) Recreation
d) Effect the anchorage of tree and lower plants
e) Ozone depletion
f) Some kind of diseases.
26. Threats to biological diversity
Global climate change
Carbon dioxide
Methane
Green house effect
All create a global warming and cause climate
change
27. Threats to biological diversity
Over exploitation
The over exploitation cause the serious damage to the wild life
because when population exploitation starts that habitat will at
risk to facilitate them for housing , agricultural uses ,and
farming.
Maximum sustainable yield
The maximum sustainable yield is the greatest amount of the
resources that can be harvested each year and replaced by
natural population growth.
Calculations using the population growth rate and the carrying
capacity are used to estimate the maximum sustainable yield .
In high controlled situations in which a resource can be easily
quantified , it may possible to achieve sustainable use.
28. Threats to biological diversity
Introductions of exotic species
The geographical ranges of many species are restricted by major
environmental and climatic barriers to dispersal .
Mammals of north America are unable to cross the pecific to reach
Hawaii.
Marine fishes in the Caribbean are unable to cross central America to
reach the pacific .
Fresh water fishes in one African lake have no way of crossing the land to
reach nearby isolated lakes.
Many species introductions have occurred by the following means
1) European colonization European settlers arriving at new colonies
released hundreds of European bird and mammal species in places like
New Zealand , Australia ,and south Africa to make the country side
seem familiar and to provide game for hunting .
29. Threats to biological diversity
2)Horticulture and agriculture Large number of plant species
have been introduced and grown in new regions as ornamentals
,agricultural crops, or pasture grasses. Many of these species have
escaped from cultivation and have become established in the local
community .
3) Accidental transport species are often transported by people
unintentionally; common examples include weed seed that are
accidentally harvested with commercial seed and snow in new localities ,
rats and insects that trow way abroad ships and airplanes, and disease
and parasitic organisms transported along with their host species.
Effects of such exotic introduction
1. The great majority of exotic species do not become established in the
places to which they are introduced because the new environment is
not suitable to their needs. However many of these increase in
abundance at the expense of native species .
30. Threats to biological diversity
2. These exotic species may displace native species through
competition for limiting resources .
3. Introduction of exotic species may result to prey on native species
.
Exotic species on islands
The effects of the exotic species are greatest on islands and in continental
area that have experienced human disturbance.
Effects of exotic species on islands
a) Plants of Santa Catalina island has adversely effected by exotic
mammals.
b) Birds of the pacific Islands the brown tree snake introduced
exotically in the pacific ocean island which ate up the eggs and
nesting of the birds and damage the bird species which are
endemic to that islands.
31. Threats to biological diversity
Exotic species in aquatic habitat
Exotic species can have effects on lakes , streams , and even entire marine
ecosystem. Fresh water communities in particular are similar to oceanic
islands in that they are isolated habitats surrounded by vast stretches of
uninhabitable terrain and are like wise vulnerable to the introduction of
exotic species. Commercial and sports fish often introduced into aquatic
environment where they do not naturally occur.
Effects
a) Aggressive exotic species would prey the endemic species and our
natural endemic population would extinct or vulnerable to the
environment .
b) In 1988 an alarming invasion resulted in north America by the cause of
exotic introduction.
c) Trout fish is an exotic species ,introduced in our northern area which
preyed our endemic species.
32. Threats to biological diversity
Exotic species to invade
They introduced the pests and parasites of new variety to new
habitat that damage unrecoverable. Spread uncontrollably,
grazing native plants to the extinction level.
Effects
a) Exotic species can more readily adapted than native species
b) Exotic species are considered to be serous threat facing the
biota of the USA National park system.
c) As aggressive species increase, they do so at the expense of
native species that are less competitive and less able to resist
predation.
33. Threats to biological diversity
Increased spread of disease
It may cause the new trait of parasites.
Due to food competition lower the nutritional level
which give rise to weak and non resistant animals to
the environment.
Basic principle of epidemiology have obvious practical
implications for captive breeding and management of
species .
Highly dense population promotes the diseases.
The interaction b/w captive and wild or exotic species
may cause of disease spread.
34. Threats to biological diversity
Vulnerability to extinction
When environments are damaged by human activity the population sizes
of many species will be reduced and some species will become extinct.
Species that are especially vulnerable to extinction fall into one or more
of the following categories.
1) Species with narrow geographical range
2) Species with only one or a few populations
3) Species in which population size small
4) Species in which population size is declining
5) Species that need a large home range
6) Species with low population densities
7) Species with a large body size
8) Species that are not effective dispersers
9) Seasonal migrants
10) Species with little genetic variability
11) Species with specialized niche requirement
35. Threats to biological diversity
12) species that are characteristically found in stable environment
13) Species that form permanent or temporary aggregations
14) Species that are hunted or harvested by people
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