Heart-shaped ivies, sometimes called sweethearts, have a leathery look and are rarely lobed. Miniatures are slow growers and the smallest ivies. Their largest leaves are no bigger than 3/4 inches long and 1/2 inch wide; they make good terrarium subjects. An ivy plant can fall into more than one of these categories.
The second main cause of genetic variation is due to the high degree of neutrality of most mutations. Most mutations do not appear to have any selective effect one way or the other on the organism. The main cause is genetic drift, this is the effect of random changes in the gene pool. In humans, founder effect and past small population size (increasing the likelihood of genetic drift) may have had an important influence in neutral differences between populations.
Genetic variation is a term used to describe the variation in the DNA sequence in each of our genomes. Genetic variation is what makes us all unique, whether in terms of hair colour, skin colour or even the shape of our faces. There are lots of different mutations that can occur in our DNA.