What is the Extinction?n

موضوع: What is the Extinction?n 17/3/2012, 19:51

itroduction

Nature : I am the environment
that is mean the natural world in which people plants and animals live . So I
am the mother of species .In the past I
was mean the beauty and the security But look what I become today .

Damages : I kill the nature . I am
the destruction . I the extinction of

life and my children are
pollution . desiccation deforestation . But in

fact I am not the guilt
.this is my teacher ….

Human being : I am not the guilt.
cupidity enslave me and these

dangers are my means to
make the best life for my sons .

Sons : bed of wood …games
…clothes of fur .Dad ; I want to go to the

zoo so as to see lions
…elephants and birds

Human being: I am sorry my son .I can
not aggress my mother nature .forgive
me Mom .if the days aid me I was not
accused for neglect I repented .I will be make a way to correct my mistakes
soon

… What is the Extinction ?

where the last person dies from

some kind of moment of extinction,

although it is usually the ability

toreproduce may be lost before the

death of another individual in this

species.
Extinction
is the isappearance and the impossibility of the final appearance of the new.
Extinction of species that are not kept in the type or group alive. Extinction
may occur before the death of another individual in this species.

Where it might be the death of

another member is able to multiply in

this group or in other words stop this

species from the ability to reproduce

to ensure survival.

In biology and ecology, extinction
is the end of an organism or of a group of organisms (taxon), normally a species. The
moment of extinction is generally considered to be the death of the last
individual of the species, although the capacity to breed and recover may have been
lost before this point. Because a species' potential range
may be very large, determining this moment is difficult, and is sually done retrospectively.
This difficulty leads to phenomena such as Lazarus
taxa, where a species
presumed extinct abruptly"re-appears" (typicallyin the fossil record)
after a period of apparent absence.

[center]causes

As long as species have been evolving, species
have been going extinct. It is estimated that over 99.9% of all species that
ever lived are extinct. The average life-span of most species is 10 million
years, although this varies widely between taxa. There are a variety of causes
that can contribute directly or indirectly to the extinction of a species or
group of species. "Just as each species is unique," write Beverly and
Stephen C. Stearns, "so is each extinction .
the causes for each are varied—some subtle and complex, others obvious and simple

General causes

Genetics and
demographic phenomena

: Extinction
Vortex and Genetic erosion

Population genetics and demographic phenomena
affect the evolution, and therefore the risk of extinction, of species. Limited
geographic range is the most important determinant of genus extinction .Natural
selection acts to propagate beneficial genetic traits and eliminate
weaknesses. It is nevertheless possible for a deleterious mutation to be spread
throughout a population through the effect of genetic
drift

Genetic pollution

Purebred wild species evolved to a specific ecology can be
threatened with extinction through the process of genetic
pollution—i.e., uncontrolled hybridization

Scorched land resulting from slash-and-burn agriculture

Habitat degradation

Habitat
degradation is currently the main anthropogenic cause of species extinctions.
The main cause of habitat degradation worldwide is agriculture, with urban
sprawl, logging, mining and some fishing practices close behind. The
degradation of a species' habitat may alter the fitness
landscape to such an extent that the species is no longer able to survive
and becomes extinct. This may occur by direct effects, such as the environment
becoming toxic,
or indirectly, by limiting a species' ability to compete effectively for
diminished resources or against new competitor species.

Natural
Causes of Extinction

Climatic
Heating and Cooling

Climate Change is caused by a number of things. The
effect that climate has on extinction is very big. Global warming is the
ongoing increase in the Earth's atmospheric and ocean temperatures created by
the greenhouse effect; a temperature increase of even 1 degree can affect plant
and animal life

Changes in Sea Levels or Currents

A small rise in the ocean floor can displace a lot of
water onto land that is already occupied. The gases from the volcanic activity
can also be absorbed by the water, thus changing the chemical composition

Asteroids/Cosmic Radiation

It is hypothesized that being exposed to too much cosmic radiation can mutate
genes, which can potentially weaken a species' gene pool in the future

Acid Rain
rain
increases the acidity of the soil which affects plant life. It can also disturb
rivers and lakes to a possibly lethal level.

Disease/Epidemic

With
the changing climate and landscape certain species are losing their ability to
fend off disease

*Natural factors usually occur at a
slower rate than human factors and therefore cause a lower extinction
rate. Human activities occur at a faster rate and cause higher extinction
rates. Human activities are mostly responsible for the present extinction
rates

Human
Causes of Extinction

*Increased human population
*Destruction/Fragmentation of Habitat
*Pollution
*Climate Change/Global Warming

Big example

In Australia—earliest
humans: 64,000 years ago; extinction--30,000-60,000 years ago

•In the Americas—80% of large animals
became extinct around the same time as first human presence there

Habitat Degradation

Habitat
loss and degradation affect 86% of all threatened birds, 86% of mammals and 88%
of threatened amphibians. Deforestation and urbanization combine to create two
reasons why plants and animals become extinct. Deforestation is leveling
forests to harvest the wood or create space for building or agriculture

What is the Extinction?n 13320085431

موضوع: رد: What is the Extinction?n 17/3/2012, 20:00

Nature ….nature

What is the Extinction?n Moon1%5B1%5D

to insure the future

موضوع: رد: What is the Extinction?n 6/4/2012, 17:21

جزاك الله خيرا ونفع بك
What is the Extinction?n 5713

موضوع: رد: What is the Extinction?n 15/12/2012, 10:59

Good topic
I really like it
THANKS

موضوع: ..........؟؟؟؟؟ 15/12/2012, 18:31

Oh! you are welcome

موضوع: رد: What is the Extinction?n 31/5/2013, 20:06

It is a best topic

thank you so much