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:
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:
