ISOLATIONashakp1998143@#£123456668999998

MSC zoology

1. I S O L A T ION P A T T E R N AND M E C H ANISM

2. C O N T E N T S I N T R O DUC TION D E F I N I T I ON H I S T ORY I S O L A T I NG M E C H A NISM P R E M E A T I N G M E C H A N I SM POSTMATING MECHANISM O R I G I N O F R E P R ODUCTIVE I S O LATION CONCLUSION REFERENCE

3. I N T R O DU CTION I s o lation i s t h e s e g regation of the p o p ulation o f a s p e c i e s i n t o s m a ller u n i ts o r s e c t ions OR T h e s e g regation of i n d ividuals o f d ifferent species b y c e r tain m e c h anisms , s o a s t o p r e vent i n t e r b r e e ding among t h em a nd h e lp i n m a i n t a ining t h e i r h e r e d i tary integrity . T h u s i t h e lp s i n s p l i tting t h e s p e c i e s i n t o s e p arate g r o u ps a n d t h e ir e v o l ution i n t o d i s t i n ct s p e c i es .

4. D E F I N I T I ON " I t 's a f a c t t hat e a c h s p e c i es o f a n i m a ls h a s d e v i c e s w h i ch p e r m it t h e r e c o g nition a n d b r i n g i n g t o g e t her o f c o s p e c i f i c i n d i v i d u a l s o f t h e o p p osite s e x w i th Sach a d e g ree o f c e r t a i nly t h a t h y b r i d i zation o c c u r s o n l y a s a n a b n o rmal e x c e p tion "

5. H I S T ORY W A N G E R ( 1 8 6 8 ) e m p h a siz e d t h e r o l e o f g e o g r a p h i c i s o l ation i n t h e f o r m a t ion of s p e c i e s . P A T E R S ON . 1 9 5 T h e t e r m i s o l a t i n g m e c h a n i s m w a s c o i n e d b y D O B Z H A NSKY' ( 1 9 3 7 ) i n h i s c l a s s i c w o r k " g e n e t i cs a n d t h e origin o f s p e c i es "

6. I S O LATING M E C H A N I S M Premeating m e c h a n i s m 's . G e o g r a phic o r s p a t i a l i s o l ation . I s o l ation d u e t o d i s t a nce . C l i m a t i n g i s o l ation . Sea s o n a l i s o l ation . H a b i t a t i s o l ation . Ethological i s o l ation . mechanical i s o l ation . physiolog i c a l i s o l ation

7. I S O LATI NG MECHANISM P O S T M A T I N G MECHANIS M'S . G a m e t i c m o r t a l i t y . Z y g o t i c m o r t a l i t y . H y b r i d i n v i a b i l i t y . H y b rid s t e r i l i t y

8. G e o g r a phic i s o l ation I n t h i s i s o l ation t w o p o p u lation a r e s e p arat e d b y s o me p h y s ical b a r r i ers . . t h e s e b a r r i ers m i g h t b e m o u n tain r a n g e s , d e s e r t , t h i k f o r e s t s l a n d b a r r iers o r w a t e r c o n n ection e t c . . i t p r e v e nt m i g r a tion a n d intermingling o f t h e i n d ividual o f t w o p o p u lation s . . H e n c e g r e a t ly r e d uce t h e e x c h ange o f g e n e s b e t w e e n t h e m . . S o t h a t t h e n e w m u t a t ion s , g e n e t i c d r i f t s a n d a c t i o n o f n a t u r a l s e lection o c c e r i n d e p e n d e n t l y i n located p o p u lations .

9. E x a m p l e D i s t r i b ution o f l a n d s n a i l s i n Hawaiian i s l a n d ( i s l a n d o f O a h u ) a f f o rd s a n e x a mple o f g e o g r a phic isolation

10. I s l a n d o f Oahu S n a i l s o f Oahu i s l a n d