The presence of vertebral column or notochord at any stage of life in any organism is the characteristic of vertebrate.
Explanation:
An animal is vertebrate if it fulfils the following criteria:
Presence of vertebral column or notochord.
Presence of endoskeleton or backbone.
The spinal cord runs above the vertebral column.
Humans embryo has notochord which becomes a vertebral column.
The alimentary canals end in the anus.
Mouth is present ta the anterior side of the vertebrate.
Have legs, fins or wings for movement.
Presence of a nervous system and sensory organs.
Presence of skin, lungs or gills.
Presence of a circulatory system.
Vertebrates include fish, amphibians, reptiles, birds and mammals.
 
        
             
        
        
        
It is a result of. Erosion
        
                    
             
        
        
        
The new hydrophilic amino acid would not form the same interactions with hydrophobic R groups. As a consequence,   protein's 3D structure would likely be affected.
Different types of amino acids have different properties and thus form different interactions. For example, hydrophobic amino acids (water-repelent) such as alanine, valine, leucine, isoleucine, proline, phenylalanine, cysteine and methionine. participate in van der Waals type of interactions. They often form the hydrophobic core of the protein which doesn’t interact with water surrounding.
On the other hand, hydrophilic amino acids (arginine, asparagine, glutamine, aspartat..) are polar, can dissolve in the water and can join the hydrogen bond network.