<u>Answer:</u>
<em>It is not true to say that common ancestors occurs only within a single species rather two species with similar traits might have a common ancestor. </em>
<u>Explanation:</u>
If the ancestor is same for both the species then it is said that both the species are closely related and share common ancestor with similar evolutionary relationship.
Phylogenetic tree are drawn and studies are done to understand the ancestor of a species. The evolution has occurred from the ancestor to the new species formed.
Genetic variation can be caused by mutation (which 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).
No that's the respiratory system
The giant mass of the Ice can dramatically reshape the landscape over centuries, even thousands of years by combining it with its gradual movement. The ice erodes the surface of the land and takes the broken rock soil waste away from their original locations, resulting in glacial lands.
I hope this helps ☺️
