SPECIATION

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SPECIATION

                                                                    The process by which new species are formed.
types
             There are two main types of speciation
1)   GRADUAL SPECIATION

2) ABRUBT SPECIATION



gradual speciation

It is very slow process even consume thousands of years.

Gradual speciation is again by two means.
a)  ALLOPATIC SPECIATION

b)         SYMPATIC SPECIATION


1)ALLOPATIC SPECIATION

Change in species is due to Geographical area
Which are separated by some separation barriers.
For examples, DARWIN FINCHES
found in Galapagos Island ,these finches were different from each other by different sizes and Peak shapes.
These finches were evolved from grain eating black birds.
darwin concept
                                                                       Darwin was naturalist born in England in 1809. His father wanted him to be a doctor but Darwin  wanted to be a  naturalist.
After graduation he decided to go out on voyage around the world on his ship HMS Beagle .
Beagle went to journey on 1831.
Darwin study the Charles Layyels principle of Geology which urged him that earth had evolved over time.
galapagos island
                                                                          The animals in Galapagos island were very unique . For example there were many Lizards which were able to swim.
There were many tortoise of many sizes and shapes.
He also found some finches which were quite different but same species. Some were larger and some were in smaller size.

Finches (musical voice birds )  have  different peaks.
unsolved problems for darwin
1)   Which things forced species to change ?
2) How species become complicated from sample species ?

To get answers of these unsolved questions Darwin read Thomas Maltus easy on “Principle of Population” .
 Maltus says that divide constantly rapidly and fight for limited resources for their survival on this Base Darwin gives idea of “Natural Selection”

natural selection
In England there were two types of moth.
Light and dark colour.
When dark moth sit on the white tree become clear and be hunt while on the other side light moth were not hunted because of light colour advantage.
So the population of white become increase.
After the developing of industries the dust of industries changed the color of white stem of trees to black. So this advantage went to dark moth and light moth on dark stem become clear. This cause to increase the no
Dark moth and light moth now very smaller in numbers or we can say near to extinct.

2)sympatic speciation




Speciation occurring in same geographical area.
The behavior of organism in envirnment is called Niche.
The have different Habits.





ABRUBT SPECIATION




It is sudden changes occurs in species due to
a) Mutation
 b) Hybridization

due to mutation
                                                            The permanent alteration of the nucleotide sequence of the genome of an organism.


For example ,in chromosomal mutation
The formation of Raphanobrassica               Raphanobrassica




REPHANOWS                        BRASICCA
SATIRUS                                OLERACEA
2N=18                                                                       2N=18
N=9                                                                           N=9
                                                    2N(9 + 9 =18 )
                                          CHROM.DOUBLING
                                                   (18+18=36 )     4n
It will become tetraploid.


hybradization
                                                                                 Hybrid speciation is a form of speciation where in hybridization between two different species leads to a new species
For example,





 Triticum Aestivum              Triticum                                   Aegilops                                       Monococum                           Speltoids
n=7                                               n=7

                             2n=14
                            4n=28
                     Trinticum durum

T.durum                            Aegilops Speltoids
4n=28                                     2n=14
Meiosis
2n=14                                      n=7

                           3n=21  

 

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