Geographical variation refers to differences among populations in genetically based traits across the natural geographic range of a species. ... In the simplest case, we divide these factors into purely genetic versus environmental components to tease apart their relative contributions to observed phenotypic variation.
Answer:
The intervertebral discs of the spinal column and 'long bones' such as the femur and tibia.
Explanation:
The answer is <span>They both suggest that snakes evolved from an ancestor with legs.
The second choice is not correct since we have no information about pythons and other snakes. We only have the relationship between geckos, snakes and legless eels. So, it is said that </span><span>snakes in general have more DNA sequences in common with four-legged geckos than they do with legless eels. This means that snakes are closer to geckos than the legless eels. We cannot conclude from this information which evolved from which, but we can say that </span><span>snakes evolved from an ancestor with legs.
In different case, if the snakes had more DNA sequence in common with legless eels, we would conclude that the snakes evolved from an ancestor without legs.</span>
