Answer:
The presence of fins in both species represents an adaptation to the same environment (i.e., sea), but in no way does this adaptation means close evolutionary homology between fishes and mammal cetaceans (whales)
Molecular evidence would include DNA
by comparing Gene sequence, you can tell which species have the most genes in common
Enzymes are biological catalysts. Catalysts lower the activation energy for reactions. The lower the activation energy for a reaction, the faster the rate. Thus enzymes speed up reactions by lowering activation energy.
Mutations are changes that occurs in our DNA sequence, either due to mistakes when the DNA is copied or as the result of environmental factors such as UV light and cigarette smoke.
They increase the genetic variation within a species because they can create entirely new alleles in a population, random mating, random fertilization, and recombination between homologous chromosomes during meiosis which reshuffles alleles within an organism's offspring.
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