Question

Why is DNA more accurate than examining physical traits in determining evolutionary relationships? Is there any case in which physical traits would have to be used instead of DNA

Answer 1

Answer:

Sequence homology in DNA molecules indicate evolutionary relationships among species or species groups, while structural similarities may be a result of functional convergence in order to eventually realize the same functions instead of evolutionary relationships

Answer 2

Answer:

Genetically DNA  codes for proteins and if two organisms  show some evolutionary relationship definitely they must share the same  or almost the same protein sequence .

Consequently,  if species of organisms survive till today, they must have inherited certain traits or gene from their parents.These parents must have resistance against selection pressure ( due to mutation in their DNA)which gives them  selection advantage,  above other species and therefore made them to be better adapted, and reproduce to populate their environment and evolved. And passed the traits to their offspring.

Therefore  evolutionary  relationship  among species should be based on examining the protein sequence from the DNA which was  responsible for the survival of the two species of organism, and therefore their evolution.

DNA-DNA hybridization where DNA strands from two different species  were  chopped, mixed, and recombined to observe their similarities.

Gene Sequencing  where a specific DNA is sequence to determine  differences and similarities with  similar genes or closely related genes, and then determine the evolutionary relationship based on the extent of closeness.

Is there any case in which physical traits would have to be used instead of DNA?

This is not reliable because it may be difficult to know if the specific  characteristic  belong to  adults or juvenile.To  work this out large numbers of the  fossil materials will be needed to undertake this, which might not be available. Thus evolutionary relationships may be difficult to undertake

Analogy ;the physical traits  may be similar in  different organism which are not related but developed to survive under the same  environmental factors. e.g wings of insects,and birds.which are used  for flying but different  morphologies and embryology, This can not be used for  evolution relationships.

Rapid variation with one species of organism may make it difficult to use the physical traits to determine the evolutionary relationships. This is  because the unevenness in the physical traits may make it difficult to  study and determine the evolutionary relationship.

Explanation: